Nitrogen and water are important variables that influence both grain yield and quality of wheat. The present study was conducted to investigate the combined effects of N and water on the growth, water use, yield and grain protein concentration of stubbled-in winter wheat produced in Saskatchewan. Seven field experiments were conducted between 1984 and 1986 on a range of soil types. Irrigation to approximately 150% of normal growing season precipitation significantly increased grain yield in five of the seven trials. A significant water × N interaction was recorded for grain yield in the remaining two trials. Grain yield response to irrigation averaged 10.9 kg ha−1 mm−1 at total available N levels above 140 kg ha−1. In trials where residual soil NO3–N to 61 cm averaged 40 kg ha−1, 62% of the grain yield increase was due to fertilizer N while 38% of the grain yield increase was due to the interaction between water and fertilizer N. Increases in grain yields due to N and water were attributed to increased levels of pre-anthesis dry matter, a higher number of kernels per square meter and an improved water use efficiency (kg ha−1 grain mm−1 total crop water use). The semidwarf cultivar Norwin and the tall cultivar Norstar responded similarly to N fertilization. In one trial, where moisture conditions were very favorable, a water × cultivar interaction indicated a greater response of Norwin to irrigation. The Gompertz equation was used to describe grain protein concentration-N response. The coefficient that describes the initial lag phase of this function was correlated with dry matter at anthesis (r = 0.97**) and root zone extractable water at stem elongation (r = 0.85**). These observations demonstrate that as pre-anthesis growing conditions improve more N is required to produce an increase in grain protein concentration above a minimum 8.2%.
No takes yet. Share an insight, caveat, or question.
Entz et al. (1989) studied this question.