Effect of Varied N‐fertilization on Yield Formation of Winter Wheat under Particular Consideration of Mainstems and Tillers

Two‐year field trials with winter wheat in nine N‐fertilizer treatments were conducted in southern Bavaria to investigate the basis of yield stability and yield superiority of N‐fertilization strategies with emphasis on N‐application during stem elongation. In measurements of individual plants the contribution of mainstems and tillers to yield formation was examined. While grain yield showed only slight differences, significant differences between harvest indices were observed among the fertilizer treatments. High harvest indices were regularly recorded in low stand densities. Individual plant analysis proved that early N‐application led to high stand densities which intensified reduction processes during ear development. N‐fertilization with emphasis on stem elongation lessened reduction processes. Low yield of tillers was mainly attributed to a low grain number per ear. Differences in grain yield between mainstems and tillers could not be modified by means of N‐fertilizer treatment. Highest yields on mainstems as well as on tillers were recorded in N‐fertilizer treatment with emphasis on stem elongation. This study demonstrates that an excessive initiation of yield components causes an unproductive consumption of resources which is detrimental to yield formation. It is concluded that optimum N‐fertilizer treatment should aim at plant stands with strong individual plants which can be achieved by emphasis of N‐fertilization during stem elongation. The stimulation of the initiation of yield organs is of minor importance as compared to a decrease of reduction process.