2013 journal article
Nitrate Uptake Rates of Kentucky Bluegrass Genotypes and Their Effect on Nitrate Absorption under Competitive Conditions
CROP SCIENCE, 53(3), 1179–1188.
UN Sustainable Development Goal Categories
Source: Web Of Science
Added: August 6, 2018
ABSTRACTNitrate leaching from turfgrasses continues to be a concern. It is proposed that selecting turfgrass genotypes with higher NO3− absorption abilities could reduce NO3− leaching. This study examined the intraspecific difference in NO3− absorption among Kentucky bluegrass (Poa pratensis L.) genotypes and how such a difference affects N absorption when roots are in competition for soil N. A nutrient solution screening procedure was used to identify Kentucky bluegrass genotypes having high vs. low NO3− uptake capacity. Tillers of 60 Kentucky bluegrass cultivars were rooted and transferred to a continuous flow solution culture system. After establishment, plants were treated to develop moderate N deficiency. Isotopically labeled (15N) KNO3 was introduced at high (1 mM) and low (0.05 mM) concentrations to screen for differences in NO3− uptake. After a brief uptake period, plants were harvested, dried, and analyzed for 15N content to determine N uptake rate. There were significant differences among genotypes for uptake rate at both high and low N concentrations. The 60 genotypes exhibited a wide range of uptake rates, with strong correlation between rates at high and low N. The cultivars Julia and Midnight were selected as representing cultivars with efficient and inefficient NO3− uptake, respectively. Julia had NO3− uptake rates averaging 56% higher than Midnight. A subsequent lysimeter study examined whether higher NO3− uptake capacity would translate into increased N absorption under competitive conditions. Tillers of the two cultivars were planted as a mixed stand in soil or sand column lysimeters. After establishment, 15N‐labeled KNO3 solution at high (2 or 1mM) and low (0.05mM) concentrations was applied to each column. After an uptake period, individual plants of each cultivar were harvested for 15N analysis. Results indicated that Julia absorbed 20 to 50% more NO3− than Midnight at the high N concentration and 25 to 71% more NO3− more than Midnight at the low N concentration. Most differences were statistically significant. This indicates that differences in NO3− absorption by Kentucky bluegrass identified in solution culture translate into differences in absorption of soil N.