The purpose of this study was to evaluate differences between winter wheat varieties in response to nitrogen fertilizer. Seven nitrogen fertilizer rate x variety factorial experiments were conducted in several environments. Dry matter and nitrogen yields at boot, soft dough, and harvest and grain yield components were measured. The yield component data were evaluated in terms of storage capacity which is assumed to be proportional to kernels /rn2 for a given variety. The kernels /m2 was divided into two components, spikes /rn2 and kernels/spike. The spikes /m2 of each variety were closely related to the boot nitrogen yield, but not to boot dry matter yield or plant nitrogen content. Since the kernels/spike generally remained constant or increased as the boot nitrogen yield increased, the kernels/m2 appeared to depend on the boot nitrogen yield. The variety Hyslop had high dry matter and nitrogen yields at boot stage of growth. This appears to allow it to have excellent storage capacity as measured by kernels /m2 . Good growth by boot stage appears to lower the nitrogen fertilizer rate needed for maximum grain yields. The variety Nugaines had relatively low growth and nitrogen uptake by boot. This may be the reason why it needs a higher fertilizer rate than Hyslop to obtain adequate storage capacity (kernels/m2). However; Nugaines had better growth after soft dough stage. At the dryland locations this may be due to slower depletion of the soil water. At the irrigated locations it may be due to greater late tillering. Hyslop and Nugaines differed in the pattern of yield component adjustment to improving environment. Hyslop mainly increased its average kernels/spike rather than spikes/m2 . Nugaines had greater increases in spikes/m2 but smaller increases in kernels/spike. This may be related to their different cuim sizes and tillering. Hyslop forms a few large culms early in the season, but Nugaines continues to tiller during stem elongation. Coulee was intermediate between Hyslop and Nugaines in patterns of growth over time and pattern of yield component adjustment to improving environment. It had good yields at moderate nitrogen rates, and high nitrogen rates did not appear to be needed for adequate storage capacity. Wanser consistently had low grain yields, which was due to low kernels/m2 . Nitrogen fertilizer increased its height more than the shorter varieties and this was associated with reductions in kernels/spike: Thus the height growth of Wanser may compete with its ear development and cause poor storage capacity. Wanser had slightly greater grain nitrogen percentage than other varieties, but this was simply associated with its low grain yield. There were only small varietal differences in the percentage of plant nitrogen translocated to grain. However, environment and nitrogen fertilizer rate greatly affected this. The club wheat Paha yielded well but usually less than some other varieties. It had high dry matter and nitrogen yields, but after soft dough its dry matter yields decreased more than for other varieties. This indicated that it depleted soil moisture earlier than other varieties did. Tx65A1268, a short hard red winter wheat with prolific tillering and small culms, was included in. two experiments. It had the highest grain yield at the low rainfall site. This may be related to its early maturity. However, with irrigation it yielded poorly. This appeared to be due to poor storage capacity since there was no increase in kernels/spike with improving environment. Yamhill, an awnletted wheat, yielded well in the Willamette Valley, but not in eastern Oregon. Estimates of the recovery of fertilizer nitrogen were calculated from the increases in soft dough nitrogen yield caused by each increment of nitrogen fertilizer. At sites with excellent moisture supply the first fertilizer increment was incompletely recovered (44-66%), apparently due to immobilization associated with plant residue decay. With higher fertilizer increments which increased yields, fertilizer recovery values were near 100%. At low rainfall sites under fallow cropping recovery values were 38-56% and decreased with above optimum fertilizer rates. At eastern Oregon sites losses of nitrogen from the plant tops after soft dough ranged from 7-33% depending on variety, location, and fertilizer rate. At maturity the percentage of the total plant top nitrogen in the grain ranged from 60-81%. This percentage decreased with nitrogen fertilization, but was little affected by variety.

Increasing nitrogen use efficiency (NUE) and nitrogen response in winter wheat could help producers reduce input costs associated with nitrogen fertilizers and decrease the negative environmental impacts of N loss. The objectives of this research were to i) establish if there are genetic differences in NUE and other related parameters among wheat varieties commonly grown in the Great Plains, ii) determine if there are differences in N response among select varieties with a range of NUEs, and iii) determine if NUE influences N response. This information could be useful in future breeding efforts as researchers seek to develop more efficient varieties. This was approached by conducting two separate studies, a large NUE study with 25 winter wheat varieties, and a smaller N Rate study with 4 varieties that represented a range of NUEs based on the preliminary results of the NUE study. The NUE study was conducted over the course of several seasons and locations, with treatments of consisting of N Rate and variety. The experiment was laid out in a strip-plot design and replicated four times at each location. In the 2010-11 and 2011-12 seasons it was planted at the Kansas River Valley Experiment Field in Rossville, KS. In the 2012-13 season the experiment was planted at two locations, one at Silverlake and another at Ashland Bottoms, KS. The experiment was again planted at two locations in the fall of 2013, in Ashland Bottoms, KS, and Hutchinson, KS. The wheat varieties were grown with two N rates, 0 kg N ha−1 and 90 kg N ha−1. Nitrogen use efficiency was calculated as the grain yield per unit of available nitrogen (sum of soil N and fertilizer N) and ranged from 22-30 kg of grain per kg of N and was strongly influenced by variety with a p

This Directory lists 1425 recent and current fertilizer projects concerned with agronomic, economic, and marketing research in the United States, Puerto Rico, and the Virgin Islands.

The grain yield of winter wheat (Triticum aestivum L.) increased over time through plant breeding, and preliminary research suggested that yield response to fertilizer differs in modern versus historical genotypes. However, this response is not universal. We hypothesize selection for yield may have unintentionally modified the dynamics of nutrient uptake and partitioning in the plant. Thus, our objectives were to identify the key shifts in crop phenotype, in above-ground biomass and in dynamics of nutrient uptake and partitioning during vegetative and reproductive phases in response to selection for yield and to in-furrow fertilizer. Field experiments were conducted in four Kansas environments in a factorial trial combining eight winter wheat varieties released between 1920 and 2016, and two fertilizer practices (control versus 112 kg ha−1 in-furrow 12-40-0-10-1). Grain yield and grain N-removal increased non-linearly with year of release (YOR), with greater increases between 1966 and 2000. In-furrow fertilizer increased yield in ~300 kg ha−1 with no variety x fertility interactions. Grain protein concentration (GNC) related negatively to yield, and the residuals of this relationship were unaffected by YOR. Yield increase in semi-dwarf varieties were associated with shorter vegetative period and longer grain filling period, and more kernels m−2 derived from more kernels head−1. Historical varieties were taller, had thinner stems, and allocated more biomass to the stem than semi-dwarf varieties. At grain filling and maturity, shoot biomass was similar among varieties but semi-dwarf varieties allocated more dry matter to the kernels, suggesting that increases in yield derived from greater harvest index (HI) rather than greater biomass. Whole plant nutrient concentration negatively related to whole plant biomass and increased over decades for N, P, and S and decreased for K. In-furrow fertilizer increased the concentration of all nutrients. Grain-N, P, K, and S uptake increased from historical to semi-dwarf varieties; thus, nutrient HI increased with YOR, with greater increases between 1966 and 2000. Nutrient HI decreased with in-furrow fertilizer as the fertilizer increased biomass allocation to the vegetative tissues more than to the grain. Nutrient allocation rate to the head related positively to whole plant uptake rate, and YOR increased the head allocation rate for N, K, and S. There were positive and significant relationships between NHI and the HI of P, K, and S. Whole plant N uptake and P, K, and S uptake were also positively related, with ratios of 9.2, 1.1, and 15.4 for N:P, N:K, and N:S. Direct selection for grain yield modified the dynamics of nutrient uptake and partitioning over time, with semi-dwarf varieties allocating more N, P, K, and S to the grain. The ability of modern varieties to allocate more biomass and nutrients to the grain, coupled to an early maturity and longer grain filling period, increased grain yield and grain N-removal over time. However, increases in yield were greater than those in N-removal, reducing GNC. In-furrow fertilizer increased grain yield, biomass, and grain N, P, K, S uptake; nonetheless, the lack of variety x fertility interaction suggested variety response to fertility was similar.