J. T. Kelly

Genetic variability in nitrogen utilization at four growth stages in soft red winter wheat

Abstract Studies were conducted to determine relationships among nitrate reductase activity (NRA), dry weight (DW), nitrogen (N) uptake, and N concentration in soft red winter wheat (Triticum aestivwn L.). Data were collected for three growing seasons from field plots grown on a silt loam and one growing season on a sandy loam. Ten cultivars were measured under field conditions with plant samples taken at Feekes Growth Stages 6, 10, 10.5, and 11.1. NRA was measured using an in vivo assay method on fully expanded leaves representing the upper most part of the canopy. Results indicated that N uptake was highest during Stages 10.5 to 11.1, although not significantly different for all cultivars. Few differences were found among cultivars for N concentration. The NRA measured under field conditions was more stable at Growth Stage 6. Path coefficients between NRA and DW, N uptake, and N concentration varied considerably depending on the growth stage, indicating that selection for N utilization using one or more...

Relation of nitrogen utilization to yield components in soft red winter wheat

Abstract This study was conducted to characterize soft red winter wheat (Triticwn aestivum L.) cultivars for nitrogen (N) utilization efficiency and to determine which traits were most affected and the predictive value of these traits. Grain yield, number of spikes per m2, kernels/m2, kernels/spike and 1,000 kernel weight (TKW) were measured at maturity. Data were collected for three growing seasons from field plots grown on a silt loam and one growing season on a sandy loam. Results indicated that N utilization efficiency was not associated with grain yield. Kernels/m2 had the highest correlation with grain yield (r = 0.50) of the yield components. Kernels per spike had a correlation of 0.43 with grain yield. However, TKW was not correlated with grain yield. There was variation among cultivars as to how the yield components produced final grain yields. Path coefficients indicated a strong positive direct effect for kernels/spike on grain yield and N utilization efficiency. Kernels/spike was found to be t...