@article{niedziela_kim_nelson_de hertogh_2008, title={Effects of N-P-K deficiency and temperature regime on the growth and development of Lilium longiflorum 'Nellie White' during bulb production under phytotron conditions}, volume={116}, DOI={10.1016/j.scienta.2008.02.01}, number={4}, journal={Scientia Horticulturae}, author={Niedziela, C. E. and Kim, S. H. and Nelson, P. V. and De Hertogh, A. A.}, year={2008}, pages={430–436} }
 @article{holness_reddy_crozier_niedziela_2008, title={Evaluating inorganic nitrogen and rye-crimson clover mixture fertilization of spring broccoli and lettuce by (15)Nitrogen tracing and mass balance}, volume={31}, ISSN={["1532-4087"]}, DOI={10.1080/01904160802097359}, abstractNote={ABSTRACT Broccoli (Brassica oleraceaL. var. italica) and lettuce (Latuca sativaL.) were grown under greenhouse conditions with nitrogen (N) from a cover crop mixture of rye (Secale cerealeL.) and crimson clover (Trifolium incarnatumL.) and ammonium nitrate (NH4NO3). Individual cover crop species were produced with non-enriched or enriched (5 atom % NH4 15NO3) Hoagland Nutrient Solutions resulting in enriched rye [0.799% atom % 15N, 24:1 carbon (C):N ratio] and enriched clover (0.686% atom % 15N, 19:1 C:N ratio). Cover crops were applied as an equal mixture of rye and clover at 1884, 3768, and 5652 kg·ha− 1 dry weight to supply 26, 52, and 78 kg·ha− 1 N. Enriched materials were only applied at the 3768 kg·ha− 1 rate, either as enriched rye plus non-enriched clover or non-enriched rye plus enriched clover. Additional treatments consisted of an unfertilized control and three NH4NO3 fertilizer rates; 112, 224, and 336 kg·ha− 1 N for broccoli and 70, 140, and 210 kg·ha− 1 N for lettuce. Combination treatments were the standard cover crop rate (3768 kg·ha− 1) plus the lowest N fertilizer rate for each vegetable. Cover crops did not increase yield of either broccoli or lettuce, and contributed only 17% of the N in broccoli and 15% of the N in lettuce. The majority of cover crop 15N remained in the soil: 54.8% and 81.3% of rye and clover N, respectively, after broccoli harvest; and 68.1% and 79.2% of rye and clover N, respectively, after lettuce harvest. Broccoli plant tissue recoveries were 8.0% of the rye and 11.0 % of the clover 15N; while lettuce plant tissue recoveries were 6.3% (rye) and 4.1% (clover). Broccoli yield could not be assessed due to lack of floret development, but dry matter accumulation was maximized at 224 kg·ha− 1N. Lettuce yield and fertilizer N recovery efficiency (by mass balance) was maximized at 140 g·ha− 1 N.}, number={6}, journal={JOURNAL OF PLANT NUTRITION}, author={Holness, Rickie L. and Reddy, Muchha R. and Crozier, Carl R. and Niedziela, Carl E., Jr.}, year={2008}, pages={1033–1045} }
 @article{kim_niedziela_nelson_de hertogh_swallow_mingis_2007, title={Growth and development of Lilium longiflorum 'Nellie White' during bulb production under controlled environments - II. Effects of shifting day/night temperature regimes on scale bulblets}, volume={112}, ISSN={["0304-4238"]}, DOI={10.1016/j.scienta.2006.11.012}, abstractNote={One-year old scale bulblets of Lilium longiflorum Thunb. ‘Nellie White’ (Easter lily) were grown for 107 days during growth period 1 (GP-1) in six growth chambers under constant day/night temperature regimes of 30/26, 26/22, 22/18, 18/14, 14/10 and 10/6 °C. Subsequently, half of the plants in each temperature regime were transferred to 18/14 °C and the other half continued at the six constant temperature regimes. Both groups of plants were grown for an additional 89 days in growth period 2 (GP-2). Continuous temperatures of 26/22, 26/22–22/18 and 26/22–18/14 °C produced the greatest increase in basal bulb fresh weight (the main planted bulb), basal bulb circumference and stem bulb fresh weight, respectively. However, shifting these optimal temperatures to 18/14 °C during GP-2 resulted in a lower increase in basal bulb fresh weight and circumference. The optimum range for stem bulb production was expanded to 30/26–14/10 °C by shifting to 18/14 °C. The greatest increase for basal root growth occurred at 14/10–10/6 °C and for stem root growth at 14/10 °C. The temperature shift did not affect either root type. Maximum increase for stem length was at 26/22 and 22/18 °C and for stem plus leaf weight at 14/10 °C under constant temperature regimes. Transferring the plants from 10/6 to 18/14 °C resulted in the greatest increase in stem length and from 10/6 and 14/10 to 18/14 °C in the greatest increase in stem plus leaf weight. The greatest increase in the number of leaves occurred at 26/22 and 10/6 °C, but this growth parameter was unaffected by shifting to 18/14 °C, indicating that leaf number was determined in GP-1. Bulbils developed only when bulbs at high GP-1 temperature regimes (30/26 and 26/22 °C) were transferred to 18/14 °C during GP-2. Lower temperatures tended to favor an increase in flower bud production under continuous temperature regimes, while shifting to 18/14 °C increased flower bud production after initially high and low temperatures. Meristem abortion was greatest at 30/26 °C followed by 26/22 °C, but was not affected by temperature shifts in GP- 2. Thus, it is concluded that the abortion was induced or initiated during GP-1.}, number={1}, journal={SCIENTIA HORTICULTURAE}, author={Kim, S. H. and Niedziela, C. E., Jr. and Nelson, P. V. and De Hertogh, A. A. and Swallow, W. H. and Mingis, N. C.}, year={2007}, month={Mar}, pages={95–98} }
 @article{nelson_kowalczyk_niedziela_mingis_swallow_2003, title={Effects of relative humidity, calcium supply, and forcing season on tulip calcium status during hydroponic forcing}, volume={98}, ISSN={["1879-1018"]}, DOI={10.1016/S0304-4238(03)00034-7}, abstractNote={Abstract The tulip ( Tulipa gesneriana L.) cultivars ‘Abra’, ‘Christmas Marvel’, ‘Golden Melody’, and ‘Jingle Bell’ were forced hydroponically during two early forcing periods (FPs) and ‘Golden Melody’ and ‘Oscar’ during two late FP. Treatments were factorial combinations of two relative humidity (RH) levels (42 and 82%) and five Ca(NO 3 ) 2 levels (0, 2.5, 5, 10, and 20 mM). The study was conducted in growth chambers at a constant 19 °C and a 14 h daylength in which 70 μmol s −1  m −2 PPF was provided by cool white florescent lamps. Calcium uptake and accumulation were less at 82% RH as compared to 42% RH; however, the incidence of Ca deficiency symptoms did not increase at the higher RH. A 2.5 mM Ca(NO 3 ) 2 solution prevented Ca deficiency symptoms in all cultivars except ‘Abra’ during all FP. Plants in FP4 (26 March–18April) weighed less and accumulated less Ca than the same cultivars in the earlier FP. Calcium uptake and transpiration were lower in distilled water and 20 mM Ca(NO 3 ) 2 than other Ca(NO 3 ) 2 treatments after day 22 in FP1 (22 December–26 January). Total Ca content was lower in the flowers of ‘Golden Melody’ tulips forced in distilled water than the Ca(NO 3 ) 2 treatments. Calcium dry weight (DW) concentration and total Ca content in the flowers of ‘Golden Melody’ tulips forced at 42% RH were higher than at 82% RH. Total Ca content in the flowers of ‘Golden Melody’ tulips decreased from FP3 to FP4.}, number={4}, journal={SCIENTIA HORTICULTURAE}, author={Nelson, PV and Kowalczyk, W and Niedziela, CE and Mingis, NC and Swallow, WH}, year={2003}, month={Sep}, pages={409–422} }
 @article{nelson_niedziela_1998, title={Effect of ancymidol in combination with temperature regime, calcium nitrate, and cultivar selection on calcium deficiency symptoms during hydroponic forcing of tulip}, volume={74}, ISSN={["1879-1018"]}, DOI={10.1016/S0304-4238(97)00158-1}, abstractNote={Experiments were conducted to determine the effect of ancymidol, as impacted by temperature, Ca(NO3)2, and cultivar, on the prevention of Ca deficiency symptoms during hydroponic forcing of tulip (Tulipa gesneriana L.). In all treatments where tulips were forced in distilled water, Ca deficiency symptoms occurred. Symptoms included scape topple; flower abortion; and chlorosis, water soaking, cracking, exudation, and purple pigmentation of the lower leaves. All symptoms except topple were avoided when tulips were forced in 5 mM Ca(NO3)2 solution. Topple was prevented by Ca(NO3)2 in a low temperature regime (21°C day–18°C night) in two of three experiments. Ca deficiency was not prevented in a high temperature regime (24°C day–21°C night). Plants forced in Ca(NO3)2 were too tall for commercial use. When forced in a solution of ancymidol, topple was prevented but all other symptoms of Ca deficiency persisted. An ancymidol rate of 0.25 mg per 650 ml pot containing five bulbs caused abortion, unrelated to Ca deficiency, in the cultivar Oscar. Forcing in a combination of 5 mM Ca(NO3)2 plus ancymidol prevented all symptoms of Ca deficiency in all experiments except in the high temperature regime of one. Ancymidol rates of 0.0625 and 0.125 mg per pot did not always provide adequate height control. A rate of 0.18 mg per pot in combination with 5 mM Ca(NO3)2 was sufficient to prevent Ca deficiency symptoms and provide adequate height control in all but one cultivar. `Jingle Bell' required an ancymidol rate of 0.24 mg for adequate height control. Prevention of topple by ancymidol did not appear to be due to the correction of Ca deficiency since ancymidol added to Ca(NO3)2 resulted in lower total Ca uptake per shoot. It was likely due to shorter, stronger scapes masking this Ca deficiency symptom.}, number={3}, journal={SCIENTIA HORTICULTURAE}, author={Nelson, PV and Niedziela, CE}, year={1998}, month={May}, pages={207–218} }
 @article{nelson_niedziela_1998, title={Effects of calcium source and temperature regime on calcium deficiency during hydroponic forcing of tulip}, volume={73}, ISSN={["1879-1018"]}, DOI={10.1016/S0304-4238(97)00157-X}, abstractNote={Tulips (Tulipa gesneriana L.) forced hydroponically in distilled water developed Ca deficiency symptoms, including topple and flower bud abortion. Prevention of Ca deficiency and uptake of Ca was greater when Ca was supplied in the NO3− form rather than as Cl− or SO42−. Calcium EDTA was injurious to plants at a concentration of 2.5 mM, a level too low to correct Ca deficiency. Addition of BO33−, K+, H2PO4−, or Hoagland's all nitrate solution with modified micronutrient levels to the Ca substrate failed to improve growth. The complete nutrient formulation reduced Ca uptake. Ca deficiency could not be prevented at the high temperature regime (22°C day–18°C night), due in part to suppress uptake of Ca. In the low temperature regime (18°C day–14°C night), a 5-mM solution of Ca(NO3)2 prevented Ca deficiency during all forcing periods. Similar results were obtained with a 7.5 mM solution of CaCl2.}, number={2-3}, journal={SCIENTIA HORTICULTURAE}, author={Nelson, PV and Niedziela, CE}, year={1998}, month={Mar}, pages={137–150} }