@article{robinson_burton_taliercio_israel_carter_2020, title={Inheritance of rhizobitoxine-induced chlorosis in soybean}, volume={60}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20193}, abstractNote={AbstractThere are two species of Bradyrhizobium that nodulate soybean [Glycine max (L.) Merr.] and fix nitrogen (N): B. japonicum and B. elkanii. Bradyrhizobium elkanii is endemic to soils in the southeastern region of the United States. Some strains of B. elkanii produce rhizobitoxine (RT), a toxin that causes chlorosis on newly developing trifoliates of some field‐grown soybean, in root nodules. Some soybean genotypes are resistant to rhizobitoxine‐induced (RI) chlorosis. The objective of this research was to determine the inheritance of soybean resistance to RI chlorosis. Crosses were made between resistant and susceptible cultivars. Progeny were identified as susceptible, resistant, or segregating in the first, second, and third self‐pollinated generations. All F1 hybrids from crosses between resistant and susceptible soybean exhibited seedling chlorosis, indicating that genes for resistance to chlorosis are recessive. The F2 progeny segregated in a ratio of nine susceptible to seven resistant, indicating that there are two genes responsible for the soybean resistance to RI chlorosis. This ratio was confirmed in F2:3 population screening. One hundred forty‐one simple sequence repeat (SSR) markers polymorphic in both a susceptible parent and a resistant parent were used to locate the genes responsible for resistance to chlorosis. A gene found near marker Satt 657 on linkage group (LG) F (chromosome 13) explained a statistically significant 32% of the phenotypic variation among F2 plants based on the p‐value and R2 of a single factor ANOVA. The second gene was not located.}, number={6}, journal={CROP SCIENCE}, author={Robinson, K. O. and Burton, J. W. and Taliercio, E. W. and Israel, D. W. and Carter, T. E., Jr.}, year={2020}, pages={3027–3034} }
 @article{roper_duckworth_grossman_israel_2020, title={Rhizobium leguminosarum strain combination effects on nodulation and biological nitrogen fixation with Vicia villosa}, volume={156}, ISSN={["1873-0272"]}, DOI={10.1016/j.apsoil.2020.103703}, abstractNote={Biological nitrogen fixation (BNF) resulting from symbiosis between legumes and rhizobia helps improve soil N fertility. Inoculated soils with specific strains of rhizobia may increase potential BNF in legumes, but the efficacy of these rhizobia in promoting BNF may be limited by competition from resident rhizobia already present in soils. We evaluated the ability of four strains to nodulate and increase BNF in Vicia villosa (hairy vetch) as individual and combined inoculants in a laboratory experiment. Plants were inoculated with a single rhizobia strain or equal ratios of 2–4 strains and grown under controlled conditions. After 46 d, entire plant shoots were harvested and analyzed for biomass, N content, nodule number, and nodule mass. Nodule occupancy was assessed using DNA fingerprinting of characteristic rhizobia genes. Negative-N and positive-N control plants averaged 6.3 and 83.2 mg total shoot N, respectively. Average total shoot N of inoculated vetch treatments was between that of uninoculated control treatments. Nodule number, total nodule mass, and BNF efficiency (total shoot N mass per total nodule mass) did not significantly differ between individual strains. Neither BNF efficiency nor nodule number were indicative of competitive ability for nodule occupancy. The rhizobia did not display any consistent synergistic or antagonistic effect on BNF when combined in inoculants and nodule occupancy did not favor any specific strain. Because vetch inoculated with local Rlv strains produced similar amounts of N as uninoculated plants fertilized with N, our work suggests that rhizobia sourced from local soils may produce sufficient BNF with vetch.}, journal={APPLIED SOIL ECOLOGY}, author={Roper, Wayne R. and Duckworth, Owen W. and Grossman, Julie M. and Israel, Daniel W.}, year={2020}, month={Dec} }
 @article{rajkovich_osmond_weisz_crozier_israel_austin_2017, title={Evaluation of Nitrogen-Loss Prevention Amendments in Maize and Wheat in North Carolina}, volume={109}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.03.0153}, abstractNote={Core Ideas
Fertilizer additives to decrease N losses did not provide consistent yield advantages.
Plots treated with N‐loss products did not increase N use efficiency or N uptake.
Agronomic optimum N rates observed in the field aligned with North Carolina recommendations.
To reduce environmental losses of N and increase crop use, it is critical to optimize N fertilization rates and determine if N‐loss prevention amendments increase yields. Research objectives were to: (i) determine N‐release patterns of three N‐loss amendments (urea ammonium nitrate [UAN] treated with NBPT+DCD, nitrapyrin, or an organo‐Ca) and UAN through a laboratory incubation; (ii) determine effectiveness of these four products for maize (Zea mays L.) and winter wheat (Triticum aestivum L.) produced in two to three regions of North Carolina; and (iii) determine agronomic optimum N rate for wheat and corn compared to state‐recommended rates. Nitrogen release was measured in three soils (coastal plain, piedmont, and mountains) during the incubation experiment. Field experiments were randomized complete block designs (four replications of six maize N rates and five wheat N rates), with each rate applied as one of four product treatments (UAN and UAN+ one of three N‐loss prevention amendments). In the incubation experiment, soils treated with UAN+nitrapyrin or UAN+NBPT+DCD delayed nitrification longer than soils treated with UAN or UAN+organo‐Ca. There was no significant effect of product on maize grain yield (coastal plain and mountains) and wheat yield (coastal plain and piedmont). A year × product interaction occurred for maize grain yield in the piedmont. Agronomic optimum N rates mostly aligned with current North Carolina N fertilizer recommendations. Despite positive laboratory results, N‐loss amendments did not have a significant effect on yield in 9 of 10 site‐years, indicating that proper N rates are a more effective nutrient management strategy.}, number={5}, journal={AGRONOMY JOURNAL}, author={Rajkovich, Shelby and Osmond, Deanna and Weisz, Randy and Crozier, Carl and Israel, Daniel and Austin, Robert}, year={2017}, pages={1811–1824} }
 @article{roberts_israel_2017, title={Influence of Soil Properties and Manure Sources on Phosphorus in Runoff during Simulated Rainfall}, volume={48}, ISSN={["1532-2416"]}, DOI={10.1080/00103624.2016.1254236}, abstractNote={ABSTRACT Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff and characterize the effects of manure sources on mass loss of dissolved reactive P, total dissolved P, and total P in runoff. Soil boxes set at 5% slopes received 7.5 cm h−1 of simulated rainfall for 30 min. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg−1. Sources of P included broiler litter, breeder manure, and breeder manure treated with three rates of aluminum sulfate (Al2(SO4)3) 0, 3.9, and 7.8 kg m−2, di-ammonium phosphate (DAP), and an un-amended control. All manure sources were surface applied at 66 kg P ha−1 without incorporation. Water extractable P represented an average of 10 ± 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, aluminum (Al), and iron (Fe) concentrations, and higher P sorption capacities that produced significantly lower dissolved reactive P, total dissolved P, and total P losses than the Coastal Plain soil. Runoff P loss did not differ significantly for low and high STP Coastal Plain soils. Water extractable P in manures accounted for all dissolved reactive P lost in runoff with dissolved reactive P correlating strongly with water extractable P concentration (r2 = 0.9961). Overall, manures containing the highest water extractable P concentrations contributed to the largest amounts of dissolved reactive P in runoff. Manure treated with 3.9 and 7.8 kg m−2 of Al2(SO4)3 (alum) decreased dissolved reactive P in runoff by 29%. While this soil box runoff study represents a worst-case scenario for P loss, highly significant effects of soil properties and manure sources were obtained. Management based on these results should help ameliorate harmful effects of P in runoff.}, number={2}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Roberts, John and Israel, Daniel W.}, year={2017}, pages={222–235} }
 @article{israel_smyth_2015, title={Crop Utilization of Nitrogen in Swine Lagoon Sludge}, volume={46}, ISSN={["1532-2416"]}, DOI={10.1080/00103624.2015.1043459}, abstractNote={Swine lagoon sludge is commonly applied to soil as a source of nitrogen (N) for crop production but the fate of applied N not recovered from the soil by the receiver crop has received little attention. The objectives of this study were to (1) assess the yield and N accumulation responses of corn (Zea mays L.) and wheat (Triticum aestivum) to different levels of N applied as swine lagoon sludge, (2) quantify recovery of residual N accumulation by the second and third crops after sludge application, and (3) evaluate the effect of different sludge N rates on nitrate (NO3-N) concentrations in the soil. Sludge N trials were conducted with wheat on two swine farms and with corn on one swine farm in the coastal plain of North Carolina. Agronomic optimum N rates for wheat grown at two locations was 360 kg total sludge N ha−1 and the optimum N rate for corn at one location was 327 kg total sludge N ha−1. Residual N recovered by subsequent wheat and corn crops following the corn crop that received lagoon sludge was 3 and 12 kg N ha−1, respectively, on a whole-plant basis and 2 and 10 kg N ha−1, respectively, on a grain basis at the agronomic optimum N rate for corn (327 kg sludge N ha−1). From the 327 kg ha−1 of sludge N applied to corn, 249 kg N ha−1 were not recovered after harvest of three crops for grain. Accumulation in recalcitrant soil organic N pools, ammonia (NH3) volatilization during sludge application, return of N in stover/straw to the soil, and leaching of NO3 from the root zone probably account for much of the nonutilized N. At the agronomic sludge N rate for corn (327 kg N ha−1), downward movement of NO3-N through the soil was similar to that for the 168 kg N ha−1 urea ammonium nitrate (UAN) treatment. Thus, potential N pollution of groundwater by land application of lagoon sludge would not exceed that caused by UAN application.}, number={12}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Israel, Daniel W. and Smyth, T. Jot}, year={2015}, month={Jul}, pages={1525–1539} }
 @article{graves_liwimbi_israel_heugten_robinson_cahoon_lubbers_2011, title={Distribution of ten antibiotic resistance genes in E. coli isolates from swine manure, lagoon effluent and soil collected from a lagoon waste application field}, volume={56}, ISSN={["0015-5632"]}, DOI={10.1007/s12223-011-0019-z}, abstractNote={The prevalence of ten antibiotic resistance genes (ARGs) was evaluated in a total of 616 Escherichia coli isolates from swine manure, swine lagoon effluent, and from soils that received lagoon effluent on a commercial swine farm site in Sampson County, North Carolina (USA). Isolates with ARGs coding for streptomycin/spectinomycin (aadA/strA and strB), tetracycline (tetA and tetB), and sulfonamide (sul1) occurred most frequently (60.6-91.3%). The occurrence of E. coli isolates that carried aadA, tetA, tetB, and tetC genes was significantly more frequent in soil samples (34.0-97.2%) than in isolates from lagoon samples (20.9-90.6%). Furthermore, the frequency of isolates that contain genes coding for aadA and tetB was significantly greater in soil samples (82.6-97.2%) when compared to swine manure (16.8-86.1%). Isolates from the lagoon that carried tetA, tetC, and sul3 genes were significantly more prevalent during spring (63.3-96.7%) than during winter (13.1-67.8%). The prevalence of isolates from the lagoon that possessed the strA, strB, and sul1 resistance genes was significantly more frequent during the summer (90.0-100%) than during spring (66.6-80.0%). The data suggest that conditions in the lagoon, soil, and manure may have an impact on the occurrence of E. coli isolates with specific ARGs. Seasonal variables seem to impact the recovery isolates with ARGs; however, ARG distribution may be associated with mobile genetic elements or a reflection of the initial numbers of resistant isolates shed by the animals.}, number={2}, journal={FOLIA MICROBIOLOGICA}, author={Graves, A. K. and Liwimbi, L. and Israel, D. W. and Heugten, E. and Robinson, B. and Cahoon, C. W. and Lubbers, J. F.}, year={2011}, month={Mar}, pages={131–137} }
 @article{israel_taliercio_kwanyuen_burton_dean_2011, title={Inositol Metabolism in Developing Seed of Low and Normal Phytic Acid Soybean Lines}, volume={51}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2010.03.0123}, abstractNote={While inositol has key roles in phytic acid and raffinosaccharide synthesis, its concentration in developing seed of low phytic acid soybean [Glycine max (L.) Merr.] lines derived from CX1834 (Wilcox et al., 2000) has not been compared to that of normal lines. Concentrations of metabolites in the phytic acid and raffinosaccharide biosynthesis have been measured in mature seed of CX1834‐derived lines but not throughout seed development. Our objective was to compare concentrations of inositol and metabolites associated with phytic acid and raffinosaccharide synthesis in developing seed of CX1834‐derived and normal lines. Plants were cultured with complete nutrient solutions in growth chambers with 650 to 700 μmol m−2 s−1 of photosynthetically active radiation and a 26/22°C day/night temperature. Seed inositol concentrations were high (60 to 90 mmol kg−1 seed dry wt.) at 20 d after flowering (DAF) and decreased 95% by maturity in both normal and low phytic acid lines. In two of three experiments, low phytic acid lines had significantly (p ≤ 0.05) greater seed inositol concentrations than normal lines at the first two sampling dates, but differences at maturity were not significant. Seeds of low phytic acid and normal lines had statistically similar concentrations (p > 0.05) of partially phosphorylated inositol intermediate (inositol triphosphate [IP3]), stachyose, raffinose, and phytase activity throughout development. These results corroborate previous studies that ruled out defects in genes coding myo‐inositol‐1‐P synthase, inositol kinases, and phytase as the basis for the low seed phytic acid trait in CX1834‐derived lines.}, number={1}, journal={CROP SCIENCE}, author={Israel, Daniel W. and Taliercio, Earl and Kwanyuen, Prachuab and Burton, Joseph W. and Dean, Lisa}, year={2011}, pages={282–289} }
 @article{hashimoto_smyth_israel_hesterberg_2010, title={LACK OF SOYBEAN ROOT ELONGATION RESPONSES TO MICROMOLAR MAGNESIUM ADDITIONS AND FATE OF ROOT-EXUDED CITRATE IN ACID SUBSOILS}, volume={33}, ISSN={["1532-4087"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-73149088156&partnerID=MN8TOARS}, DOI={10.1080/01904160903434279}, abstractNote={Additions of micromolar concentrations of magnesium (Mg) to hydroponics enhance aluminum (Al) tolerance of soybean by increasing citrate secretion from roots and external complexation of toxic Al species. The objective of this study was to assess the ameliorative effect of Mg additions on soybean root elongation into mineralogically different acid soils. Roots of soybean seedlings grew for 28 days into acid soils treated with three Mg levels in their soil solution (Control, 150 and 300 μM) and lime. Root growth in the acid soils and aboveground dry matter responses to the Mg treatments were less than for the lime treatments. Citrate fate in the acid soils revealed that 66–99% of added citrate was either adsorbed or biodegraded, suggesting that root secreting citrate in the soil abundant with Al and iron (Fe) hydroxides potentially reduces the availability to complex rhizotoxic Al. A calcium (Ca) deficiency may have constrained root growth response to the Mg-treated soils.}, number={2}, journal={JOURNAL OF PLANT NUTRITION}, author={Hashimoto, Yohey and Smyth, T. Jot and Israel, Daniel W. and Hesterberg, Dean}, year={2010}, pages={219–239} }
 @article{cahill_osmond_israel_2010, title={Nitrogen Release from Coated Urea Fertilizers in Different Soils}, volume={41}, ISSN={["1532-2416"]}, DOI={10.1080/00103621003721437}, abstractNote={The nitrogen (N) release from coated urea fertilizers (Arborite and ESN), traditional N fertilizers [urea, (NH2)2CO], and urea ammonium nitrate (UAN) [(NH2)2CO, NH4NO3] in three North Carolina (USA) soils was measured throughout a 12-week laboratory incubation. Treatments were N source and moisture level (60% and 80% of field capacity). In both the Candor and Cecil soils, 40% of the Arborite N had released by day 2 after addition to the soil. Maximum Arborite N release was achieved by week 6 for both soils. The ESN N release began between weeks 1 and 2, and maximum release was attained by week 6 for the Candor and by week 8 for the Cecil soil. The ESN reached 70% release on Portsmouth by week 8 and Arborite had an immediate release. Field studies of these coated ureas would be needed to determine if they are economically viable over more traditional N fertilizers in North Carolina.}, number={10}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Cahill, Sheri and Osmond, Deanna and Israel, Daniel}, year={2010}, pages={1245–1256} }
 @article{muruganandam_israel_robarge_2010, title={Nitrogen Transformations and Microbial Communities in Soil Aggregates from Three Tillage Systems}, volume={74}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2009.0006}, abstractNote={Quantifying N transformation processes in soil aggregates is relevant since microbial communities central to the N cycle may differ among aggregate size fractions. Our objective was to test the hypothesis that variations in microbial community composition of aggregate size fractions influence N transformation rates of soil from three long‐term (22‐yr) tillage systems (no‐till, chisel plow, and moldboard plow). Aggregate size fractions (2–4, 0.5–1, and <0.25 mm) were obtained by dry sieving. Nitrogen transformation rates were estimated by analysis of 15N pool dilution data with the FLUAZ model, and microbial community composition by phospholipid fatty acid (PLFA) profiles. Aggregate size fraction and tillage system had significant (P < 0.01) effects on total and microbial biomass C and N, gross N mineralization rate (GNMR), gross nitrification rate (GNR), and gross N immobilization rate (GIR). No‐till soils and the 0.5‐ to 1.0‐mm aggregate size fraction had the highest N transformation rates. Net N mineralization rates were greater for no‐till than for tilled soils. Multiple response permutation analysis of PLFA data revealed that microbial community composition did not differ with aggregate size fraction. Stepwise regression analysis indicated that microbial community composition (nonmetric multidimensional scaling Axis 1) accounted for 89% of the variation in GIR, soil C and N concentrations accounted for 88% of the variation in GNMR, and microbial biomass C concentration accounted for 81% of the variation in GNR. These results indicate that greater N transformation rates in no‐till than tilled soil were due primarily to increased microbial biomass (i.e., microbial population size) rather than altered microbial community composition.}, number={1}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Muruganandam, Subathra and Israel, Daniel W. and Robarge, Wayne P.}, year={2010}, pages={120–129} }
 @article{muruganandam_israel_robarge_2009, title={Activities of Nitrogen-Mineralization Enzymes Associated with Soil Aggregate Size Fractions of Three Tillage Systems}, volume={73}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2008.0231}, abstractNote={Nitrogen mineralization occurring near the soil surface of agroecosystems determines the quantity of plant‐available N, and soil enzymes produced by microorganisms play significant roles in the N mineralization process. Tillage systems may influence soil microbial communities and N mineralization enzymes through alterations in total soil C and N. Soil aggregates of different sizes provide diverse microhabitats for microorganisms and therefore influence soil enzyme activities. Our objective was to test the hypothesis that activities of N mineralization enzymes increase with aggregate size and in no‐till compared with tilled systems. Potential activities of N‐acetyl glucosaminidase (NAG), arylamidase, l‐glutaminase, and l‐asparaginase were measured in five aggregate size fractions (<0.25, 0.25–0.5, 0.5–1, 1–2, and 2–4 mm) obtained from soils of three long‐term (22‐yr) tillage systems (no‐till, chisel plow, and moldboard plow). All enzyme activities were significantly (P < 0.05) greater in no‐till than in tilled systems and positively correlated (P < 0.005) with potential N mineralization. Potential activities of NAG, l‐glutaminase, and arylamidase were significantly greater (P < 0.05) in the intermediate (0.5–1‐mm) aggregate size than in other size fractions. All enzyme activities were positively correlated with total soil C (P < 0.0001), N (P < 0.05), and microbial biomass C (P < 0.05). Aggregate size had significant effects on NAG, arylamidase, and l‐glutaminase activities but the magnitudes were small. Fungal biomarkers (18:2ω6c and 16:1ω5c) determined by the phospholipid fatty acid (PLFA) method were significantly greater in the no‐till than in tilled systems and positively correlated with all enzyme activities. This suggests that no‐till management enhances activities of N mineralization enzymes by enhancing the proportion of fungal organisms in the soil microbial community.}, number={3}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Muruganandam, Subathra and Israel, Daniel W. and Robarge, Wayne P.}, year={2009}, pages={751–759} }
 @article{perez_smyth_israel_2007, title={Comparative effects of two forage species on rhizosphere acidification and solubilization of phosphate rocks of different reactivity}, volume={30}, DOI={10.1080/01904160701556778}, abstractNote={ABSTRACT Dissolution of phosphate rocks (PR) in soils requires an adequate supply of acid (H+) and the removal of the dissolved products [calcium (Ca2 +) and dihydrogen phosphate (H2PO4 −)]. Plant roots may excrete H+ or OH− in quantities that are stoichiometrically equal to excess cation or anion uptake in order to maintain internal electroneutrality. Extrusion of H+ or OH− may affect rhizosphere pH and PR dissolution. Differences in rhizosphere acidity and solubilization of three PRs were compared with triple superphosphate between a grass (Brachiaria decumbens) and a legume (Stylosanthes guianensis) forage species at two pH levels (4.9 and 5.8) in a phosphorus (P)-deficient Ultisol with low Ca content. The experiment was performed in a growth chamber with pots designed to isolate rhizosphere and non-rhizosphere soil. Assessment of P solubility with chemical extractants led to ranking the PRs investigated as either low (Monte Fresco) or high solubility (Riecito and North Carolina). Solubilization of the PRs was influenced by both forage species and mineral composition of the PR. The low solubility PR had a higher content of calcite than the high solubility PRs, which led to increased soil pH values (> 7.0) and exchangeable Ca, and relatively little change in bicarbonate-extractable soil P. Rhizosphere soil pH decreased under Stylosanthes but increased under Brachiaria. The greater ability of Stylosanthes to acidify rhizosphere soil and solubilize PR relative to Brachiaria is attributed to differences between species in net ion uptake. Stylosanthes had an excess cation uptake, defined by a large Ca uptake and its dependence on N2 fixation, which induced a significant H+ extrusion from roots to maintain cell electroneutrality. Brachiaria had an excess of anion uptake, with nitrate (NO3 −) comprising 92% of total anion uptake. Nitrate and sulfate (SO4 2 −) reduction in Brachiaria root cells may have generated a significant amount of cytoplasmic hydroxide (OH−), which could have increased cytoplasmic pH and induced synthesis of organic acids and OH− extrusion from roots.}, number={7-9}, journal={Journal of Plant Nutrition}, author={Perez, M. J. and Smyth, T. J. and Israel, D. W.}, year={2007}, pages={1421–1439} }
 @article{israel_osmond_roberts_2007, title={Potential impacts of implementation of the phosphorus loss assessment tool (PLAT) on the poultry industry in North Carolina: Case studies}, volume={62}, number={1}, journal={Journal of Soil & Water Conservation}, author={Israel, D. W. and Osmond, D. L. and Roberts, J. C.}, year={2007}, pages={48–54} }
 @article{israel_kwanyuen_burton_walker_2007, title={Response of low seed phytic acid soybeans to increases in external phosphorus supply}, volume={47}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2006.11.0691}, abstractNote={Commercialization of soybean [Glycine max (L.) Merr.] varieties with low seed phytic acid will depend on the stability of the trait when grown in soils with a wide range of P availabilities and on the impact of altered P composition on seed protein and oil concentrations. Impacts of deficient (0.05 mmol L−1) to excessive (0.9 to 1.2 mmol L−1) levels of external P on seed P composition of normal and low phytic acid lines and of altered seed P composition on seed protein and oil synthesis were evaluated. Soybean lines homozygous recessive (pha/pha) at one of two loci with genes that condition the low seed phytic acid trait had the same greater‐than‐threefold increase in phytic acid in response to increasing external P as their normal phytic acid parent, ‘AGS Prichard‐RR’ (Pha/Pha). This supports the conclusion from previous inheritance studies that the low seed phytic acid trait in CX1834‐1‐2 is controlled by epistatic interaction between two independent recessive genes. The seed phytic acid concentration in the low phytic acid line G03PHY‐443 (derived from CX1834‐1‐2) was <2 g phytic acid P kg−1 dry wt. when grown under deficient to excessive external P. As the P supply increased, seed inorganic P concentrations for this line increased from 0.8 to 4.0 g kg−1 dry wt., compared to an increase of 0.2 to 0.6 g kg−1 dry wt. for the normal phytic acid lines. Seed protein and oil concentrations did not differ significantly between normal and low phytic acid lines. These results support continued development of varieties with low seed phytic acid and high yields.}, number={5}, journal={CROP SCIENCE}, author={Israel, D. W. and Kwanyuen, P. and Burton, J. W. and Walker, D. R.}, year={2007}, pages={2036–2046} }
 @article{iyyemperumal_green_israel_ranells_shi_2008, title={Soil chemical and microbiological properties in hay production systems: residual effects of contrasting N fertilization of swine lagoon effluent versus ammonium nitrate}, volume={44}, ISSN={["1432-0789"]}, DOI={10.1007/s00374-007-0221-y}, number={3}, journal={BIOLOGY AND FERTILITY OF SOILS}, author={Iyyemperumal, Kannan and Green, James, Jr. and Israel, Daniel W. and Ranells, Noah N. and Shi, Wei}, year={2008}, month={Feb}, pages={425–434} }
 @article{hashimoto_smyth_hesterberg_israel_2007, title={Soybean root growth in relation to ionic composition in magnesium-amended acid subsoils: Implications on root citrate ameliorating aluminum constraints}, volume={53}, ISSN={["1747-0765"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-36249018938&partnerID=MN8TOARS}, DOI={10.1111/j.1747-0765.2007.00191.x}, abstractNote={Abstract Hydroponic studies with soybean (Glycine max [L.] Merr.) have shown that µmol L−1 additions of Mg2+ were as effective in ameliorating Al rhizotoxicity as additions of Ca2+in the mmol L−1 concentration range. The objectives of this study were to assess the ameliorative effects of Mg on soybean root growth in acidic subsoils and to relate the soil solution ionic compositions to soybean root growth. Roots of soybean cultivar Plant Introduction 416937 extending from a limed surface soil compartment grew for 28 days into a subsurface compartment containing acid subsoils from the Cecil (oxidic and kaolinitic), Creedmoor (montmorillonitic) and Norfolk (kaolinitic) series. The three Mg treatments consisted of native equilibrium soil solution concentrations in each soil (50 or 100 µmol L−1) and MgCl2 additions to achieve 150 and 300 µmol L−1 Mg (Mg150 and Mg300, respectively) in the soil solutions. Root elongations into Mg-treated subsoils were compared with a CaCO3 treatment limed to achieve a soil pH value of 6. Subsoil root growth responses to the Mg treatments were less than for the lime treatments. Root length relative to the limed treatments for all subsoils (RRL) was poorly related to the activity of the soil solution Al species (Al3+ and Al-hydroxyl species) and Mg2+. However, the RRL values were more closely related to the parameters associated with soil solution Ca activity, including (Ca2+), (Al3+)/(Ca2+) and (Al3+)/([Ca2+] + [Mg2+]), suggesting that Ca could be a primary factor ameliorating Al and H+ rhizotoxicity in these subsoils. Increased tolerance to Al rhizotoxicity of soybean by micromolar Mg additions to hydroponic solutions, inducing citrate secretion from roots to externally complex toxic Al, may be less important in acid subsoils with low native Ca levels.}, number={6}, journal={SOIL SCIENCE AND PLANT NUTRITION}, author={Hashimoto, Yohey and Smyth, T. Jot and Hesterberg, Dean and Israel, Daniel W.}, year={2007}, month={Dec}, pages={753–763} }
 @article{cahill_osmond_crozier_israel_weisz_2007, title={Winter wheat and maize response to urea ammonium nitrate and a new urea formaldehyde polymer fertilizer}, volume={99}, DOI={10.2134/agronj2OO7.0132}, number={6}, journal={Agronomy Journal}, author={Cahill, S. and Osmond, Deanna and Crozier, C. and Israel, D. and Weisz, R.}, year={2007}, pages={1645–1653} }
 @article{moyer-henry_burton_israel_rufty_2006, title={Nitrogen transfer between plants: A N-15 natural abundance study with crop and weed species}, volume={282}, ISSN={["1573-5036"]}, DOI={10.1007/s11104-005-3081-y}, number={1-2}, journal={PLANT AND SOIL}, author={Moyer-Henry, K. A. and Burton, J. W. and Israel, D. W. and Rufty, T. W.}, year={2006}, month={Apr}, pages={7–20} }
 @article{tungate_israel_watson_rufty_2007, title={Potential changes in weed competitiveness in an agroecological system with elevated temperatures}, volume={60}, ISSN={["0098-8472"]}, DOI={10.1016/j.envexpbot.2006.06.001}, abstractNote={Increases in temperature due to global climate changes could significantly impact weed competitiveness and crop–weed interactions. Factors contributing to the responsiveness of a plant species to increasing temperature include the inherent genetic limitations of the species and the ability to acquire water and nutritional resources. The purpose of this study was to examine the temperature responses of selected species from a model agronomic system in the Southeastern U.S.: soybean (Glycine max), sicklepod (Senna obtusifolia) and prickly sida (Sida spinosa). We also determined temperature effects on mycorrhizal colonization and development of the soybean N2-fixation system, two below-ground associations critical for resource acquisition. The species were grown at 42/37 (day/night), 36/31, 32/27, 28/23, or 23/18 °C for 30 days in a field soil with naturally low fertility. Growth of the weed species was maximized at a higher temperature than that for soybean, 36/31 °C versus 32/27 °C, probably reflecting different geographical origins. At the optimal temperature, weeds had higher root:shoot mass ratios (1.3–1.5 versus 0.9) than soybean, and greater mycorrhizal colonization. In soybean, nodule weights, numbers, and total nitrogenase activity were highest at the growth temperature optimum but decreased considerably at higher temperatures. The results collectively indicate that increases in aerial temperatures above ∼32 °C would enhance weed competitiveness. Increased interference with soybean growth and yields should be expected.}, number={1}, journal={ENVIRONMENTAL AND EXPERIMENTAL BOTANY}, author={Tungate, Kimberly D. and Israel, Daniel W. and Watson, Dorothy M. and Rufty, Thomas W.}, year={2007}, month={May}, pages={42–49} }
 @article{iyyemperumal_israel_shi_2007, title={Soil microbial biomass, activity and potential nitrogen mineralization in a pasture: Impact of stock camping activity}, volume={39}, ISSN={["0038-0717"]}, DOI={10.1016/j.soilbio.2006.07.002}, abstractNote={Grazing animals recycle a large fraction of ingested C and N within a pasture ecosystem, but the redistribution of C and N via animal excreta is often heterogeneous, being highest in stock camping areas, i.e., near shade and watering sources. This non-uniform distribution of animal excreta may modify soil physical and chemical attributes, and likely affect microbial community eco-physiology and soil N cycling. We determined microbial population size, activity, N mineralization, and nitrification in areas of a pasture with different intensity of animal excretal deposits (i.e., stock camping, open grazing and non-grazing areas). The pasture was cropped with coastal bermudagrass (Cynodon dactylon L.) and subjected to grazing by cattle for 4 y. Soil microbial biomass, activity and N transformations were significantly higher at 0–5 cm than at 5–15 cm soil depth, and the impacts of heterogeneous distribution of animal excreta were more pronounced in the uppermost soil layer. Microbial biomass, activity and potential net N mineralization were greater in stock camping areas and were significantly correlated (r2≈0.50, P<0.05) with the associated changes in total soil C and N. However, gross N mineralization and nitrification potential tended to be lower in stock camping areas than in the open grazing areas. The lower gross N mineralization, combined with greater net N mineralization in stock camping areas, implied that microbial N immobilization was lower in those areas than in the other areas. This negative association between microbial N immobilization and soil C is inconsistent with a bulk of publications showing that microbial N immobilization was positively related to the amount of soil C. We hypothesized that the negative correlation was due to microbial direct utilization of soluble organic N and/or changes in microbial community composition towards active fungi dominance in stock camping areas.}, number={1}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Iyyemperumal, Kannan and Israel, Daniel W. and Shi, Wei}, year={2007}, month={Jan}, pages={149–157} }
 @article{hernandez-sebastia_marsolais_saravitz_israel_dewey_huber_2005, title={Free amino acid profiles suggest a possible role for asparagine in the control of storage-product accumulation in developing seeds of low- and high-protein soybean lines}, volume={56}, ISSN={["1460-2431"]}, DOI={10.1093/jxb/eri191}, abstractNote={Several approaches were taken to examine the role of N-assimilate supply in the control of soybean (Glycine max) seed composition. In the first study, developing seeds were grown in vitro with D-[U-14C]sucrose (Suc) and different concentrations of Gln. Light stimulated carbon flux into oil and protein, and was required to sustain Suc uptake and anabolic processes under conditions of elevated nitrogen supply. High Gln supply resulted in higher transcript levels of beta-conglycinin and oleosin. In the second study, analyses of soluble amino acid pools in two genetically related lines, NC103 and NC106 (low- and high-seed protein, respectively) showed that, in the light, NC106 accumulated higher levels of Asn and several other amino acids in developing cotyledons compared with NC103, whereas at the seed coat and apoplast levels both lines were similar. In the dark, NC103 accumulated Gln, Arg, and its precursors, suggesting a reduced availability of organic acids required for amino acid interconversions, while NC106 maintained higher levels of the pyruvate-derived amino acids Val, Leu, and Ile. Comparing NC103 and NC106, differences in seed composition were reflected in steady-state transcript levels of storage proteins and the lipogenic enzyme multi-subunit acetyl CoA carboxylase. In the third study, a positive correlation (P < or = 0.05) between free Asn in developing cotyledons and seed protein content at maturity was confirmed in a comparison of five unrelated field-grown cultivars. The findings support the hypothesis that high seed-protein content in soybean is determined by the capacity of the embryo to take up nitrogen sources and to synthesize storage proteins. Asn levels are probably tightly regulated in the embryo of high-protein lines, and may act as a metabolic signal of seed nitrogen status.}, number={417}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Hernandez-Sebastia, C and Marsolais, F and Saravitz, C and Israel, D and Dewey, RE and Huber, SC}, year={2005}, month={Jul}, pages={1951–1963} }
 @article{silva_ferrufino_sanzonowicz_smyth_israel_junior_2005, title={Interactions between magnesium, calcium, and aluminum on soybean root elongation}, volume={29}, ISSN={["0100-0683"]}, DOI={10.1590/s0100-06832005000500010}, abstractNote={Alleviation of Al rhizotoxicity by Ca and Mg can differ among species and genotypes. Root elongation of soybean [Glycine max (L.) Merr.] line N93-S-179 and cvs. Young and Ransom exposed to varying concentrations of Al, Ca and Mg were compared in two experiments using a vertically split root system. Roots extending from a surface compartment with limed soil grew for 12 days into a subsurface compartment with nutrient solution treatments maintained at pH 4.6 with either 0 or 15 µmol L-1 Al. Calcium and Mg concentrations in treatments ranging from 0 to 20 mmol L-1. Although an adequate supply of Mg was provided in the surface soil compartment for soybean top growth, an inclusion of Mg was necessary in the subsurface solutions to promote root elongation in both the presence and absence of Al. In the absence of Al in the subsurface solution, tap root length increased by 74 % and lateral root length tripled when Mg in the solutions was increased from 0 to either 2 or 10 mmol L-1. In the presence of 15 µmol L-1 Al, additions of 2 or 10 mmol L-1 Mg increased tap root length fourfold and lateral root length by a factor of 65. This high efficacy of Mg may have masked differences in Al tolerance between genotypes N93 and Young. Magnesium was more effective than Ca in alleviating Al rhizotoxicity, and its ameliorative properties could not be accounted for by estimated electrostatic changes in root membrane potential and Al3+ activity at the root surface. The physiological mechanisms of Mg alleviation of Al injury in roots, however, are not known.}, number={5}, journal={REVISTA BRASILEIRA DE CIENCIA DO SOLO}, author={Silva, IR and Ferrufino, A and Sanzonowicz, C and Smyth, TJ and Israel, DW and Junior, TEC}, year={2005}, pages={747–754} }
 @article{israel_showers_fountain_fountain_2005, title={Nitrate movement in shallow ground water from swine-lagoon-effluent spray fields managed under current application regulations}, volume={34}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2004.0338}, abstractNote={ABSTRACTRapid increases in the swine (Sus scrofa domestica) population in the 1990s and associated potential for nitrate N pollution of surface waters led the state of North Carolina to adopt stringent waste management regulations in 1993. Our objectives were to characterize (i) nitrate N movement from waste application fields (WAFs) in shallow ground water, and (ii) soil, hydrologic, and biological factors influencing the amount of nitrate N in the adjacent stream. A ground water monitoring study was conducted for 36 mo on a swine farm managed under new regulations. Water table contours and lack of vertical gradients indicated horizontal flow over most of the site. Nitrate N concentrations in water from shallow wells in WAFs averaged 30 ± 19 mg L−1 and δ15N ratios for nitrate N were between +20 and +25 per mil. Nitrate N concentration decreased from field‐edge to streamside wells by 22 to 99%. Measurement of δ18O and δ15N enrichment of nitrate in ground water throughout the WAF–riparian system indicated that denitrification has not caused significant 15N enrichment of nitrate. Over a 24‐mo period, δ15N ratios for nitrate N in the stream approached δ15N ratios for nitrate N in ground water beneath WAFs indicating delivery of some waste‐derived nitrate N to the stream in shallow ground water. Nitrate N concentrations in the stream were relatively low, averaging 1 mg L−1 Dilution of high nitrate N water in shallow horizontal flow paths with low nitrate N water from deeper horizontal flow paths at or near the stream, some denitrification as ground water discharges through the stream bottom, and some denitrification in riparian zone contributed to this low nitrate N concentration.}, number={5}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Israel, DW and Showers, WJ and Fountain, M and Fountain, J}, year={2005}, pages={1828–1842} }
 @article{moore_israel_mikkelsen_2005, title={Nitrogen availability of anaerobic swine lagoon sludge: sludge source effects}, volume={96}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2004.04.013}, abstractNote={Increased numbers of swine producers will be removing sludge from their anaerobic waste treatment lagoons in the next few years, due to sludge exceeding designed storage capacity. Information on availability of nitrogen (N) in the sludge is needed to improve application recommendations for crops. The objective of this study was to investigate possible effects of different companies and types of swine operations on the availability of N in sludge from their associated lagoons. A laboratory incubation study was conducted to quantify the availability of N (i.e. initial inorganic N plus the potentially mineralizable organic N) in the sludge. Nine sludge sources from lagoons of sow, nursery and finishing operations of three different swine companies were mixed with a loamy sand soil (200 mg total Kjeldahl N kg(-1) soil) and incubated at a water content of 0.19 g. water g(-1) dry soil and 25+/-2 degrees C for 12 weeks. Samples were taken at eight times over the 12-week period and analyzed for inorganic N (i.e. NH(4)-N and NO(3)-N) to determine mineralization of organic N in the sludge. Company and type of swine operation had no significant effects (P < 0.05) on the pattern of inorganic N accumulation over time. Thus, inorganic N accumulation from all sludge sources was fit to a first order equation [Nt = Ni + No (1-e(-kt)]. This relationship indicated that of the 200 mg of total sludge N added per kg soil, 23.5% was in the form of potentially mineralizable organic N (No) and 17.5% was in the form of inorganic N (Ni). The sum of these two pools (41%) represents an estimate of the proportion of total N in the applied sludge in plant available form after the 12 week incubation. While plant N availability coefficients were not measured in this study, the lack of significant company or type of swine operation effects on sludge N mineralization suggests that use of the same plant N availability coefficient for sludge from different types of lagoons is justifiable. The validity of this interpretation depends on the assumption that variation in other components of different sludge sources such as Cu and Zn does not differentially alter N uptake by the receiver crops.}, number={3}, journal={BIORESOURCE TECHNOLOGY}, author={Moore, AD and Israel, DW and Mikkelsen, RL}, year={2005}, month={Feb}, pages={323–329} }
 @article{moore_mikkelsen_israel_2004, title={Nitrogen mineralization of anaerobic swine lagoon sludge as influenced by seasonal temperatures}, volume={35}, ISSN={["1532-2416"]}, DOI={10.1081/CSS-120030575}, abstractNote={Abstract As anaerobic swine lagoons approach maximum sludge storage capacity, producers must periodically remove sludge and apply it to nearby fields. Information regarding the availability of nitrogen (N) in sludge as a nutrient source applied at different seasons of the year could improve crop-use efficiency. A 12-month laboratory study was conducted to quantify the effects of seasonal temperatures on mineralization of N in lagoon sludge. Sludge was mixed with a Coastal Plain soil (Arenic Kandiudult) and incubated for one year at weekly fluctuating temperatures based on Winter, Spring, Summer, and Fall application dates, ranging from a Winter low temperature of 9°C to a Summer maximum temperature of 30°C. Samples were analyzed monthly for NO3-N and NH4-N in 1.0 M KCl extracts of sludge amended soil. Sludge N availability (sum of NO3-N plus NH4-N concentration in 1.0 M KCl extract) was fit to a nonlinear regression model for a first-order reaction. Net N mineralization rate constants (k) derived from these models for the initial season of application increased in the order Fall (0.07) < Winter (0.075) < Spring (0.22) < Summer (0.36). While initial rates of net N mineralization differed, N availability predicted from first order equations was similar for all temperature regimes after one year of incubation and averaged 74% of the total N applied. Forty-two to 53% of the organic N in the sludge was mineralized during the one-year incubation.}, number={7-8}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Moore, AD and Mikkelsen, RL and Israel, DW}, year={2004}, month={Apr}, pages={991–1005} }
 @article{silva_smyth_israel_rufty_2001, title={Altered aluminum inhibition of soybean root elongation in the presence of magnesium}, volume={230}, DOI={10.1023/A:1010384516517}, number={2}, journal={Plant and Soil}, author={Silva, I. R. and Smyth, T. J. and Israel, D. W. and Rufty, T. W.}, year={2001}, pages={223–230} }
 @article{silva_smyth_israel_raper_rufty_2001, title={Magnesium ameliorates aluminum rhizotoxicity in soybean by increasing citric acid production and exudation by roots}, volume={42}, ISSN={["1471-9053"]}, DOI={10.1093/pcp/pce067}, abstractNote={Superior effectiveness of Mg over Ca in alleviating Al rhizotoxicity cannot be accounted for by predicted changes in plasma membrane Al3+ activity. The influence of Ca and Mg on the production and secretion of citrate and malate, and on Al accumulation by roots was investigated with soybean genotypes Young and PI 416937 which differ in Al tolerance. In the presence of a solution Al3+ activity of 4.6 microM, citrate and malate concentrations of tap root tips of both genotypes increased with additions of either Ca up to 3 mM or Mg up to 50 microM. Citrate efflux rate from roots exposed to Al was only enhanced with Mg additions and exceeded malate efflux rates by as much as 50-fold. Maximum citrate release occurred within 12 h after adding Mg to solution treatments. Adding 50 microM Mg to 0.8 mM CaSO4 solutions containing Al3+ activities up to 4.6 microM increased citrate concentration of tap root tips by 3- to 5-fold and root exudation of citrate by 6- to 9-fold. Plants treated with either 50 microM Mg or 3 mM Ca had similar reductions in Al accumulation at tap root tips, which coincided with the respective ability of these ions to relieve Al rhizotoxicity. Amelioration of Al inhibition of soybean root elongation by low concentrations of Mg in solution involved Mg-stimulated production and efflux of citrate by roots.}, number={5}, journal={PLANT AND CELL PHYSIOLOGY}, author={Silva, IR and Smyth, TJ and Israel, DW and Raper, CD and Rufty, TW}, year={2001}, month={May}, pages={546–554} }
 @article{silva_smyth_israel_raper_rufty_2001, title={Magnesium is more efficient than calcium in alleviating aluminum rhizotoxicity in soybean and its ameliorative effect is not explained by the Gouy-Chapman-Stern model}, volume={42}, ISSN={["1471-9053"]}, DOI={10.1093/pcp/pce066}, abstractNote={The mechanistic basis for cation amelioration of Al rhizotoxicity in soybean was investigated through a series of studies comparing protective effects of Ca and Mg against Al inhibition of root elongation in a background 0.8 mM CaSO4 solution (pH 4.3). A modified Gouy-Chapman-Stern model was used to evaluate the effect of cations on electrical potential and Al3+ activity at root plasma membrane surfaces. Activities of Al3+ up to 4.6 microM in the background solution inhibited soybean tap root elongation by more than 80%. There was little or no response in root elongation when Ca and Mg were added to background solutions in the absence of AL: When added to Al-toxic solutions in the micromolar concentration range, Mg was 100-fold more effective than Ca in alleviating Al toxicity, whereas both cations were equally effective when added in the millimolar concentration range. The protective effect of micromolar additions of Mg on root elongation was specific for Al and it failed to alleviate La rhizotoxicity. In contrast to wheat, Mg amelioration of Al toxicity to soybean root elongation at low Mg concentration could not be explained by changes in potential and Al3+ activity at the root plasma membrane surfaces as predicted by a Gouy-Chapman-Stern model. These results suggest that Mg is not acting as an indifferent cation when present at low concentration and implies the involvement of a mechanism other than pure electrostatic effects at the root surface.}, number={5}, journal={PLANT AND CELL PHYSIOLOGY}, author={Silva, IR and Smyth, TJ and Israel, DW and Raper, CD and Rufty, TW}, year={2001}, month={May}, pages={538–545} }
 @article{israel_mikkelsen_2001, title={Soybean as a receiver crop for nitrogen in swine lagoon effluent}, volume={166}, ISSN={["1538-9243"]}, DOI={10.1097/00010694-200107000-00003}, abstractNote={Soybean (Glycine max L. Merr.) has been approved by the Natural Resource Conservation Service as a receiver crop for N in swine lagoon effluent applied to spray fields. However, its efficacy as a N receiver crop depends on the sensitivity of symbiotic N2 fixation to inhibition by N in the applied effluent. The objectives of this study were to use a 15N natural abundance method to (i) assess the degree of inhibition of symbiotic N2 fixation in soybean by applied effluent N and (ii) determine the quantity of effluent N removed from the soil in harvested seed of nodulating soybean. Two field experiments were conducted to evaluate seed yield; seed N accumulation and whole shoot N accumulation of nodulating and nonnodulating soybean cultivars supplied a range of N levels as either lagoon effluent or ammonium nitrate. Measurement of 15N natural abundances indicated that, on average, 27% of the N in seed of nodulating cultivars supplied 200 kg of plant-available N (PAN)/ha as swine lagoon effluent was derived from symbiotic N2 fixation. While this effluent N rate did not inhibit N2 fixation completely, seed N recovery of 100 kg effluent N/ha (1997 trial) and 64 kg effluent N/ha (1998 trial) was not different between the nodulating and nonnodulating cultivars. Similar recovery of effluent N in nodulating and nonnodulating cultivars, even though inhibition of N2 fixation by the nodulating cultivar was incomplete, resulted from the nodulating cultivars having higher yields and harvest indices than the nonnodulating cultivar. Subtraction of seed N at maturity from whole shoot N at the R6.5 growth stage (between full seed stage and physiological maturity) was used to estimate crop N returned to the soil. This estimate indicated that nodulating and nonnodulating cultivars returned similar amounts of N to the soil. Our results show that nodulating soybeans can recover as much applied effluent N in seed as a 6.3 Mg/ha (100 bu/ac) corn crop.}, number={7}, journal={SOIL SCIENCE}, author={Israel, DW and Mikkelsen, RL}, year={2001}, month={Jul}, pages={453–464} }
 @article{nakasathien_israel_wilson_kwanyuen_2000, title={Regulation of seed protein concentration in soybean by supra-optimal nitrogen supply}, volume={40}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2000.4051277x}, abstractNote={The physiological and biochemical basis for increased seed protein concentrations (SPC) observed in restriction‐index, recurrent‐selection breeding programs with soybean [Glycine max (L.) Merr.] are poorly understood. The hypothesis that soybean SPC is regulated by the supply of nitrogenous substrates available to the seed was evaluated. Effects of supra‐optimal external N on seed storage protein accumulation, amino acid concentration and composition in leaves and seeds at R5, and levels of specific storage protein subunits were measured. Genotypes with different SPC (NC 107, normal; N87‐984‐16, intermediate; and NC 111, high) were grown in controlled‐environment chambers and supplied with 30 mM N as NH4NO3 from V5 to maturity or from R5 to maturity. Control plants received 10 mM N throughout the growth cycle. Relative to control, supra‐optimal N increased SPC of NC 107 and N87‐984‐16 by an average of 28%. Greater enhancement of protein accumulation than of dry matter accumulation in the seed resulted in SPCs of 460 to 470 g kg−1, which are appreciably greater than concentrations observed for these cultivars grown in the field. Supra‐optimal N also increased SPC of the high protein line (NC 111) by 15%, but this increase resulted entirely from a decrease in yield. Supra‐optimal N supplied to NC 107 and N87‐984‐16 from V5 until R5 increased total free amino acid concentrations in seeds and leaves at R5 by an average of 21 and 46%, respectively. Enhanced accumulation of the β subunit of β conglycinin which does not contain methionine and cysteine accounted for the increase in SPC. While enhanced N availability increased the SPC of a normal protein line into the high range, availability of sulfur amino acids in the developing seed determined which storage protein subunits were synthesized from the extra N.}, number={5}, journal={CROP SCIENCE}, author={Nakasathien, S and Israel, DW and Wilson, RF and Kwanyuen, P}, year={2000}, pages={1277–1284} }
 @article{ferrufino_smyth_israel_carter_2000, title={Root elongation of soybean genotypes in response to acidity constraints in a subsurface solution compartment}, volume={40}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2000.402413x}, abstractNote={Aluminum‐tolerant germplasm is needed to overcome subsurface acidity constraints to root growth and plant access to water and nutrients. Root elongation of four soybean [Glycine max (L.) Merr.] genotypes exposed to varying concentrations of Al, H, and Ca were compared in two experiments using a vertically split root system. Roots extending from a limed surface soil compartment grew for 12 d into a subsurface compartment with nutrient solution treatments. In Exp. 1 root growth for cv. Ransom and Plant Introduction 416937 (PI) were compared in solutions with factorial combinations of pH (4.2, 5.2) and Al (0, 7.5, 15 μM) with Ca maintained at 10 mM In Exp. 2 soybean line N93‐S‐179 (N93), PI, and cultivars Ransom and Young were compared in solutions with factorial combinations of Ca (2 and 10 mM) and Al (7.5 and 15 μM) maintained at pH 4.6. Ransom and PI had similar responses in tap and lateral root elongation to solution pH and Al treatments in Exp. 1, but mean tap root length of Ransom in the subsurface compartment exceeded that of PI by 22%. Aluminum inhibited the length of lateral roots more than tap roots in both experiments. Molar activity ratios between Ca and Al3+ {Ca/Al3+} accounted for most of the differences in root elongation response among solution treatments in Exp. 2. A 50% reduction in relative length of tap roots for all genotypes occurred with a {Ca/Al3+} value of 891. Values of {Ca/Al3+} for 50% reductions in relative length of lateral roots differed among genotypes and were 1.6 to 3.5 times greater than for tap roots. On the basis of the {Ca/Al3+} indices for lateral root length, line N93 and Ransom exhibited greater tolerance to subsurface solution Al than PI and Young.}, number={2}, journal={CROP SCIENCE}, author={Ferrufino, A and Smyth, TJ and Israel, DW and Carter, TE}, year={2000}, pages={413–421} }
 @article{pantalone_rebetzke_burton_carter_israel_1999, title={Soybean PI 416937 root system contributes to biomass accumulation in reciprocal grafts}, volume={91}, ISSN={["0002-1962"]}, DOI={10.2134/agronj1999.915840x}, abstractNote={Soybean [Glycine max (L.) Merr.] plant introduction PI 416937 (PI4) has an extensive fibrous‐like root system that contributes to enhanced drought and Al tolerance. The root system of PI4 appears to be more highly nodulated than standard southern U.S. cultivars, and thus has potential for enhanced N2 fixation. Genetic transfer of PI4 root system to soybean cultivars may lead to increased seed N at harvest through increased biomass or seed protein concentration. This hypothesis has not been tested. The objective of this study was to determine the influence of PI4 root system on plant productivity and protein accumulation in soybean seedling reciprocal grafts grown to maturity in the field. In three experiments, grafts were initiated 5 d after greenhouse planting by transversely severing the hypocotyl 2 cm below the apical meristem and transferring wedge‐cut scions to severed root stock. Plants were then transplanted and grown in the field. PI 416937 maintained its superior root fibrosity in graft combination with other genotype scions. In Exp. 2, at the end of the season, plants of non‐PI4 scions grafted to PI4 root stock averaged significantly higher in root fibrosity score (8.2) than the mean of their self‐grafts (6.0); however, when PI4 scions were grafted to root stock from other genotypes, the root fibrosity score decreased significantly (6.6) compared with PI4 self graft (8.4). Thus, grafting revealed that the root system itself, rather than the scion of PI4, regulates expression of the fibrous‐like rooting trait. Seed protein concentration did not increase significantly for genotype scions grafted to PI4 root stock. In Exp. 3, ‘Lee 74’ or N85‐492 grafted to PI4 root stock had significantly higher seed dry weight (161.1 g plant−1 for Lee 74 grafted to PI4 vs. 96.4 g plant−1 for the self‐graft; 129.5 g plant−1 for N85‐492 grafted to PI4 vs. 79.4 g plant−1 for the self‐graft). The fibrous‐like root system of PI4 enhances seed biomass when grafted to some non‐PI4 genotypes. The genetic transfer of the PI4 rooting trait to elite germplasm through applied breeding may lead to the development of more productive soybean lines.}, number={5}, journal={AGRONOMY JOURNAL}, author={Pantalone, VR and Rebetzke, GJ and Burton, JW and Carter, TE and Israel, DW}, year={1999}, pages={840–844} }
 @article{sanzonowicz_smyth_israel_1998, title={Calcium alleviation of hydrogen and aluminum inhibition of soybean root extension from limed soil into acid subsurface solutions}, volume={21}, ISSN={["0190-4167"]}, DOI={10.1080/01904169809365442}, abstractNote={Abstract Alleviation by calcium (Ca) of inhibition of soybean [Glycine max (L.) Merr. cv. ‘Ransom'] root elongation by hydrogen (H) and aluminum (Al) was evaluated in a vertical split‐root system. Roots extending from a limed and fertilized soil compartment grew for 12 days into a subsurface compartment containing nutrient solution with treatments consisting of factorial combinations of either pH (4.0, 4.6, and 5.5) and Ca (0.2, 2.0, 10, and 20 mM), Al (7.5, 15, and 30 μM) and Ca (2.0,10, and 20 mM) at pH 4.6, or Ca (2, 7, and 12 mM) levels and counter ions (SO4 and Cl) at pH 4.6 and 15 μM Al. Length of tap roots and their laterals increased with solution Ca concentration and pH value, but decreased with increasing Al level. Length of both tap and lateral roots were greater when Ca was supplied as CaSO4 than as CaCl2, but increasing Ca concentration from 2 to 12 mM had a greater effect on alleviating Al toxicity than Ca source. In the absence of Al, relative root length (RRL) of tap and lateral roots amon...}, number={4}, journal={JOURNAL OF PLANT NUTRITION}, author={Sanzonowicz, C and Smyth, TJ and Israel, DW}, year={1998}, pages={785–804} }
 @article{sanzonowicz_smyth_israel_1998, title={Hydrogen and aluminum inhibition of soybean root extension from limed soil into acid subsurface solutions}, volume={21}, ISSN={["0190-4167"]}, DOI={10.1080/01904169809365410}, abstractNote={Abstract Soybean [Glycine max (L.) Merr. cv. ‘Ransom'] root elongation under varying concentrations of solution hydrogen (H) and aluminum (Al) was investigated in a vertical split‐root system. Roots extending from a limed and fertilized soil compartment grew for 12 days into a subsurface compartment with solutions adjusted to either different pH values from 3.7 to 5.5 or a factorial combination of pH (4.0,4.6, and 5.2) and Al (0,7.5, 15, and 30 μM) levels. Ionic forms of Al were estimated with GEOCHEM and solution Al was determined with ferron. Boron (B) (18.5 μM) and zinc (Zn) (0.5 μM) were supplied to all solution treatments, in addition to 2000 μM Ca, after preliminary studies at pH 5.2 without Al indicated that their omission inhibited length of tap roots and their laterals in the subsurface compartment. Both H+ and Al inhibited the length of lateral roots more than tap roots. Lateral roots failed to develop on tap roots at pH<4.3 or in treatments with 30 μM Al. Relative tap root length (RRL) among tr...}, number={2}, journal={JOURNAL OF PLANT NUTRITION}, author={Sanzonowicz, C and Smyth, TJ and Israel, DW}, year={1998}, pages={387–403} }
 @article{sa_israel_1998, title={Phosphorus-deficiency effects on response of symbiotic N-2 fixation and carbohydrate status in soybean to atmospheric CO2 enrichment}, volume={21}, ISSN={["0190-4167"]}, DOI={10.1080/01904169809365555}, abstractNote={Abstract The impact of phosphorus (P) deficiency on response of symbiotic N2 fixation and carbohydrate accumulation in soybean (Glycine max [L.] Merr.) to atmospheric CO2 enrichment was examined. Plants inoculated with Bradyrhizobium japonicum MN 110 were grown in growth chambers with controlled atmospheres of 400 and 800 μL CO2 L‐1 and supplied either 1.0 mM‐P (P‐sufficient) or 0.05 mM‐P (P‐deficient) nitrogen (N)‐free nutrient solution. When plants were supplied with sufficient P, CO2 enrichment significantly increased whole plant dry mass (83%), nodule mass (67%), total nitrogenase activity (58%), and N (35%) and P (47%) accumulation at 35 days after transplanting (DAT). Under sufficient P supply, CO2 enrichment significantly increased starch concentrations in nodules compared to the normal atmospheric CO2 treatment. Under normal CO2 levels (400 μL L‐1) nonstructural carbohydrate concentration (starch plus soluble sugar) was significantly higher in leaves of P‐deficient plants than in leaves of P‐suffi...}, number={10}, journal={JOURNAL OF PLANT NUTRITION}, author={Sa, TN and Israel, DW}, year={1998}, pages={2207–2218} }
 @article{ramirez_israel_wollum_1998, title={Using spontaneous antibiotic-resistant mutants to assess competitiveness of bradyrhizobial inoculants for nodulation of soybean}, volume={44}, ISSN={["0008-4166"]}, DOI={10.1139/cjm-44-8-753}, abstractNote={Spontaneous mutants (3/parental strain) of soybean bradyrhizobia resistant to streptomycin and erythromycin were selected from strains isolated from bradyrhizobial populations indigenous to Cape Fear and Dothan soils. These were used to evaluate (i) the validity of using antibiotic-resistant mutants to make inferences about the competitiveness of parental strains in soil environments and (ii) the recovery of strains in nodules after inoculation of soybeans grown in soils with indigenous bradyrhizobial populations. Streptomycin and erythromycin resistances of all mutants were stable after approximately 27 generations of growth in yeast extract - mannitol medium, but 33% of the mutants lost resistance to erythromycin upon passage through nodules. Only 17% of the mutants were as competitive as their parental strain when inoculated in a ratio near 1:1 in vermiculite. Four of 10 mutants, which differed in competitiveness from their parental strain in vermiculite, had competitiveness against the soil populations equal to that of their parental strain. Therefore, assessment of competitiveness of mutants and parental strains in non-soil media may not accurately reflect their competitiveness in soil systems. For both the Cape Fear and Dothan soils, recovery of a given mutant from nodules of field-grown plants was always lower than from nodules of plants grown in the greenhouse. Inoculation of the entire rooting zone in the greenhouse experiment and of only a portion of the rooting zone in the field experiments may account for this difference in recovery. Techniques that increase the volume of soil inoculated may enhance nodulation by inoculant strains.Key words: Bradyrizobium, antibiotic resistance, competition.}, number={8}, journal={CANADIAN JOURNAL OF MICROBIOLOGY}, author={Ramirez, ME and Israel, DW and Wollum, AG}, year={1998}, month={Aug}, pages={753–758} }
 @article{israel_burton_1997, title={Nitrogen nutrition of soybean grown in coastal plain soils of North Carolina}, number={310}, journal={Technical Bulletin (North Carolina Agricultural Research Service)}, author={Israel, D. W. and Burton, J. W.}, year={1997} }
 @article{ramirez_israel_wollum_1997, title={Phenotypic and genotypic diversity of similar serotypes of soybean bradyrhizobia from two soil populations}, volume={29}, ISSN={["0038-0717"]}, DOI={10.1016/S0038-0717(97)00009-6}, abstractNote={The physiological and genetic diversity within two major serotypic groups of bradyrhizobial isolates obtained from soybean (Glycine max L. Merr.) plants grown on a Dothan and a Cape Fear soil was examined. All isolates serotyped as 3194 had large colonies with smooth borders and high resistances to erythromycin, streptomycin and spectinomycin with minimal inhibitory concentration values (MIC) ranging from 200 to 400 μg ml−1. Pulsed-field gel-electrophoresis (PFGE) separation of DNA fragments generated with the rarely cutting restriction endonuclease, Xba I, revealed six genotypes among 28 different 3194 isolates. Four of these genotypes were common to both soils and only 21% of the isolates were classified as having high N2-fixation capacity. Leaf chlorosis was induced by 46% of the 3194 isolates. Among the 122124 isolates, MIC values were lower than for 3194 isolates ranging from < 13 to 200 μg ml−1. These 122124 isolates produced small colonies (50%) and large colonies with rough borders (50%) when plated on YEM. The genetic diversity of serotype 122124 isolates differed with soil type as PFGE patterns revealed nine genotypes among the 16 isolates from the mineral organic (Cape Fear) soil and only three genotypes among the 14 isolates from the sandy mineral (Dothan) soil. Only two of the 12 genotypes were common to both soils. Sixty percent of the 122124 isolates were classified as having high N2-fixation capacity and none induced foliar chlorosis. Pulsed-field gel-electrophoresis pattern was the only trait that generated groups of isolates that were similar with respect to other measured traits.}, number={9-10}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Ramirez, ME and Israel, DW and Wollum, AG}, year={1997}, pages={1539–1545} }
 @article{ramirez_israel_wollum_1997, title={Phenotypic characterization of soybean bradyrhizobia in two soils of North Carolina}, volume={29}, DOI={10.1016/S0038-0717(97)00008-4}, abstractNote={Serotypic composition of nodules (480 per soil type) from five soybean cultivars grown on two (Dothan and Cape Fear) soils of the Atlantic Coastal Plain of North Carolina was characterized. Symbiotic N2-fixation efficiency, capacity for induction of foliar chlorosis symptomatic of rhizobitoxine production and antibiotic resistances of isolates purified from these nodules were also determined. While host plant cultivar had no significant effect on the serotype distribution, soil type had a large effect on the distribution and diversity of serotypes. Forty-six serotypes were identified among nodules from the Cape Fear soil, but only serotype 4676 (8%), 76 (11%), 94 (9%) and 122124 (12%) occurred in more than 5% of the nodules. Thirty percent of nodule occupants were not identified with the eleven antisera used. Twenty-four serotypes were identified among nodules from the Dothan soil. Of these serotypes 3194 (32%), 4676 (16%), and 76 (23%) occurred in more than 15% of the nodules. Five percent of the nodule occupants were not identified. Major serotypes did not change, but their frequency changed when fields were sampled at different growth stages in the same season and at the same growth stage in different seasons. Isolates serotyped as 3194, 4676, and most of the isolates serotyped as 76 generally exhibited higher levels of resistance to streptomycin and erythromycin than isolates serotyped as 24, 94 and 122124. Five percent of the isolates from the Cape Fear soil (all serotyped as 3194) and 18% of the isolates from the Dothan soil (serotyped as 3194 or 76) induced foliar chlorosis when cultivar Brim was the host. Only 12–14% of the isolates from the two populations had N2-fixation capacity equal to or greater than that of the efficient reference strain MN110. However, four improved soybean cultivars grown in the same fields and year that isolates were obtained did not exhibit a significant seed yield response to application of 150 kg N ha−1 when yields in the minus N treatment ranged from 3.2 to 3.7 Mg ha−1. A significant seed yield response by a non-nodulated cultivar indicated that these soils were N limited. Therefore, the symbiotic N2-fixation capacity of these bradyrhizobial populations did not limit soybean seed yields despite the low percentage of isolates with high N2-fixation efficiency and the presence of isolates with the capacity to induce leaf chlorosis symptomatic of rhizobitoxine production.}, number={9-10}, journal={Soil Biology & Biochemistry}, author={Ramirez, M. E. and Israel, D. W. and Wollum, A. G.}, year={1997}, pages={1547–1555} }
 @article{israel_1993, title={Symbiotic dinitrogen fixation and host-plant growth during development of and recovery from phosphorus deficiency}, volume={88}, DOI={10.1034/j.1399-3054.1993.880213.x}, number={2}, journal={Physiologia Plantarum}, author={Israel, D. W.}, year={1993}, pages={294} }
 @article{israel_rufty_cure_1990, title={NITROGEN AND PHOSPHORUS NUTRITIONAL INTERACTIONS IN A CO2 ENRICHED ENVIRONMENT}, volume={13}, ISSN={["0190-4167"]}, DOI={10.1080/01904169009364163}, abstractNote={Abstract Nonnodulated soybean plants (Glycine max. [L.] Merr. ‘Lee') were supplied with nutrient solutions containing growth limiting concentrations of N or P to examine effects on N‐ and P‐uptake efficiencies (mg nutrient accumulated/gdw root) and utilization efficiencies in dry matter production (gdw2/mg nutrient). Nutritional treatments were imposed in aerial environments containing either 350 or 700 μL/L atmospheric CO2 to determine whether the nutrient interactions were modified when growth rates were altered. Nutrient‐stress treatments decreased growth and N‐ and P‐uptake and utilization efficiencies at 27 days after transplanting (DAT) and seed yield at maturity (98 DAT). Atmospheric CO2 enrichment increased growth and N‐ and P‐utilization efficiencies at 27 DAT and seed yield in all nutritional treatments and did not affect N‐ and P‐uptake efficiencies at 27 DAT. Parameter responses to nutrient stress at 27 DAT were not altered by atmospheric CO2 enrichment and vice versa. Nutrient‐stress treatmen...}, number={11}, journal={JOURNAL OF PLANT NUTRITION}, author={ISRAEL, DW and RUFTY, TW and CURE, JD}, year={1990}, pages={1419–1433} }
 @article{relative performance of rhizobium and bradyrhizobium strains under different environmental conditions_1988, volume={1}, number={1}, journal={ISI Atlas of Science}, year={1988}, pages={95} }
 @article{israel_jackson_1982, title={ION BALANCE, UPTAKE, AND TRANSPORT PROCESSES IN N-2-FIXING AND NITRATE-DEPENDENT AND UREA-DEPENDENT SOYBEAN PLANTS}, volume={69}, ISSN={["1532-2548"]}, DOI={10.1104/pp.69.1.171}, abstractNote={The objective of this study was to examine the influence of N(2) fixation and NO(3) (-)-N and urea-N assimilation on ion balance, uptake, and transport processes in soybean (Glycine max L. Merr.).Inoculated plants were grown in Perlite supplied daily with nutrient solutions which contained zero-N, 10 and 20 millimolar NO(3) (-)-N, and 10 and 20 millimolar urea-N, and they were sampled 41, 76, and 151 days after transplanting. Total uptake of inorganic cations and anions was determined by analysis of tissue for K(+), Ca(2+), Mg(2+), Na(+), total N from NO(3) (-), total S, H(2)PO(4) (-), and Cl(-). Differences in total inorganic cations (C) and inorganic anions (A) in plant tissue were used to estimate total carboxylate content.Internal OH(-) generation resulting from excess cation uptake (net H(+) excretion) by the roots accounted for more than 89% of the carboxylate accumulation in N(2)- and urea-fed plants, while OH(-) generation resulting from SO(4) (2-) reduction accounted for less than 11%. Shoots contained over 89% of the total plant carboxylate content. Malate balanced about 75% of the excess inorganic cationic charge of the xylem sap; allantoate and aspartate balanced most of the remaining charge. These results indicate that carboxylates (primarily malate) are synthesized in roots of N(2)- and urea-fed plants and transported to the shoots in the xylem to maintain charge balance. The high malate concentration resulted in the C/N weight ratio of xylem sap from N(2)-fed plants being >2.0, even though 83% of the N was transported as allantoin and allantoic acid which have a C/N ratio of 1.0. The data emphasize that C and N content of N compounds should not be the sole basis for calculating the C/N weight ratio of xylem sap.The C-to-A uptake ratio for plants supplied 10 millimolar NO(3) (-) ranged from 1.24 to 1.57 during development, indicating that internal OH(-) was generated both by excess cation uptake and by NO(3) (-) and SO(4) (2-) reduction. The C-to-A uptake ratio for 20 millimolar NO(3) (-) -fed plants ranged from 0.86 to 0.96 during development, indicating a small net OH(-) efflux from the roots for support of excess anion uptake. On a seasonal basis, only 15% of the OH(-) generated during NO(3) (-) and SO(4) (2-) reduction was associated with OH(-) efflux (excess anion uptake), while 85% was associated with carboxylate accumulation. The malate concentration in xylem sap from plants supplied 20 millimolar NO(3) (-) was only one-third that of N(2)- and urea-fed plants; however, it did balance 75% of the excess inorganic cationic charge. Potassium, recycling to accommodate excess anion uptake by 20 millimolar NO(3)-fed plants, was calculated to involve at most 17% of the total K(+) absorbed during the 41- to 76-day growth interval.}, number={1}, journal={PLANT PHYSIOLOGY}, author={ISRAEL, DW and JACKSON, WA}, year={1982}, pages={171–178} }
 @article{mcclure_israel_1979, title={TRANSPORT OF NITROGEN IN THE XYLEM OF SOYBEAN PLANTS}, volume={64}, ISSN={["0032-0889"]}, DOI={10.1104/pp.64.3.411}, abstractNote={Experiments were conducted to characterize the distribution of N compounds in the xylem sap of nodulated and nonnodulated soybean plants through development and to determine the effects of exogenous N on the distribution of N compounds in the xylem. Xylem sap was collected from nodulated and nonnodulated greenhouse-grown soybean plants (Glycine max [L.] Merr. "Ransom") from the vegetative phase to the pod-filling phase. The sum of the nitrogen in the amino acid, nitrate, ureide (allantoic acid and allantoin), and ammonium fractions of the sap from both types of plants agreed closely with total N as assayed by a Kjeldahl technique. Sap from nodulated plants supplied with N-free nutrient solution contained seasonal averages of 78 and 20% of the total N as ureide-N and amino acid-N, respectively. Sap from nonnodulated plants supplied with a 20 millimolar KNO(3) nutrient solution contained seasonal averages of 6, 36, and 58% of total N as ureide-N, amino acid-N, and nitrate-N, respectively. Allantoic acid was the predominant ureide in the xylem sap and asparagine was the predominant amino acid. When well nodulated plants were supplied with 20 millimolar KNO(3), beginning at 65 days, C(2)H(2) reduction (N(2) fixation) decreased relative to nontreated plants and there was a concomitant decrease in the ureide content of the sap. A positive correlation (r = 0.89) was found between the ureide levels in xylem sap and nodule dry weights when either exogenous nitrate-N or urea-N was supplied at 10 and 20 millimolar concentrations to inoculated plants. The results demonstrate that ureides play a dominant role in N transport in nodulated soybeans and that the synthesis of ureides is largely dependent upon nodulation and N(2) fixation.}, number={3}, journal={PLANT PHYSIOLOGY}, author={MCCLURE, PR and ISRAEL, DW}, year={1979}, pages={411–416} }