Nitrogen Uptake, Distribution, and Utilization in Hard Red Spring Wheat Varieties.

Hard red spring wheat (HRSW) cultivars tend to vary in their grain yield and protein concentration potential suggesting different physiological responses to accumulate dry matter and nitrogen (N) in the plant. A 3-year study was initiated in Crookston, Minnesota in 2010 to understand the N response of HRSW cultivars and to understand how those cultivars differ in accumulating and distributing dry matter and N in various parts of the plant. The experiment was setup as randomized complete block design and split-plot arrangement of treatments, replicated four times. Nitrogen rates (0, 67, 134, and 200 kg N ha^-1) were main plots while cultivars (Glenn, Faller, Samson, and Vantage) were split-plots. Plants were clipped at the ground level from two 9 ft² quadrants in each plot at jointing, anthesis, anthesis+10 days, anthesis+20 days, and at maturity to measure dry matter and N accumulation in the head, flag leaf, penultimate leaf, lower stem part and total plant (combined parts). Non-linear data analyses suggest dry matter accumulated in the head, flag leaf, and total plant varied significantly throughout the growing season among wheat cultivars and supplied N rates. From anthesis onwards Vantage accumulated relatively greater dry matter in the head, flag leaf, and total plant; Glenn accumulated the lowest dry matter in the head and total plant; and Samson accumulated the lowest flag leaf dry matter. Total dry matter accumulation was similar at the134 and 200 kg N ha^-1 rates and was greater than 0 and 37 kg N ha^-1 rate. Total N accumulation did not change among different wheat cultivars but were different among different N rates. The results from this study will be further analyzed to understand how accumulation of pre-anthesis stored dry matter accumulation contributes towards final grain yield and protein concentration.