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Physiological contributions to nitrogen use efficiency in grain sorghum
Abstract
There is a great deal of variability among grain sorghum (Sorghum bicolor (L) Moench) genotypes for N (NO$\sb3\sp-$ and/or NH$\sb4\sp+)$ uptake, assimilation, biomass production and partitioning and N use efficiency. The physiological basis by which plants achieve such diversity in interaction with environmental conditions is not understood. Studies were conducted with 15 grain sorghum genotypes separated into three groups (hybrids, U.S. adapted lines and tropical lines) at two N levels in the field and in the greenhouse. The greenhouse study was conducted using nutrient solution with different $\rm NO\sb3\sp-/NH\sb4\sp+$ ratios. Tropical lines selected under low N environment had greater capabilities to extracting N from the soil. Their rapid growth rate gave them a greater N biomass use efficiency compared to the hybrids and U.S. adapted lines which had greater grain yield potential and more favorable dry matter partitioning to grain resulting in greater grain N use efficiency. Nitrate reductase activity (NRA) did not appear to be the most limiting factor in N accumulation and use by the grain sorghum genotypes tested. The NRA decreased with plant developmental age and did not correlate to plant total N, total biomass production, nor grain yield. The study showed that grain sorghum preferred NH$\sb4\sp+$-N during early growth and NO$\sb3\sp-$-N thereafter. Increasing NH$\sb4\sp+$-N in the nutrient solution decreased total plant N, biomass N use efficiency, and altered biomass partitioning between root and shoot. Nitrogen use efficiency appeared to be a very complex phenomenon genetically controlled and environmentally regulated.
Subject Area
Agronomy|Botany
Recommended Citation
Traore, Abdoulaye, "Physiological contributions to nitrogen use efficiency in grain sorghum" (1998). ETD collection for University of Nebraska-Lincoln. AAI9839151.
https://digitalcommons.unl.edu/dissertations/AAI9839151