Effects of Nitrogen and Plant Density on Growth, Yield and Chemical Composition of Two Winter Wheat (Triticum aestivum L.) Cultivars

Abstract

A field study was conducted on the winter wheat cultivars Arminda and Okapi, using two seed rates (80 and 160 kg/ha) and three N applications (40, 80 and 120 kg/ha). The cultivars did not differ in total dry matter production but did differ in grain yield. The difference in grain yield was mainly attributable to a higher harvest index (HI). Increased plant density reduced HI; it resulted in more shoots per m2, but in a lower grain yield. The reduction in grain yield was caused by fewer kernels per ear and a lower 1000‐grain weight in both cultivars. A higher rate of N increased total dry matter production and grain yield, except in Okapi at the high plant density. The number of kernels per ear increased, but 1000‐grain weight fell. The higher the N applications, the higher the N‐content of the roots was. Total N yield was greater in Arminda than in Okapi. The cultivars differed in the amount of nitrogen they took up after anthesis. The content of water‐soluble carbohydrates (WSC) differed between the cultivars, N treatments and growth stages. Carbohydrate formed before anthesis accounted for 23 % of Arminda's grain yield and for 10 % of Okapi's grain yield. The content of cell‐wall constituents (CWC) depended on cultivar, growth stage and the rate of the N dressing. Differences in CWC were more pronounced in Arminda than in Okapi. During leaf, stem and ear development there was a strong increase in content and amount of CWC. Concomitantly, WSC decreased. This implies that a large consumption of WSC is necessary for the formation of CWC. The competition for the WSC, necessary for CWC and shoot and ear development influences kernel initiation. Per unit of dry matter Okapi contained more CWC than Arminda. This was not in agreement with differences in straw sturdiness.

Seeding density in wheat: the more, the merrier?

“…Similar results are reported for the wheat crop, with a maximum grain yield obtained at densities of 371 -508 seeds m , in distinct evaluating environments (Joseph et al, 1985;Ellen, 1990;Lock, 1993;Lloveras et al, 2004). These effects on the ideal seeding density indicate that further studies aiming to recommend an ideal density for each specific genotype and location would have an important impact on the crop.…”

Effects of nitrogen supply on wheat and on soil nitrate

“…The lower amount of spikes m -2 observed in our trials, compared with reports from central Northern Europe (Ellen, 1990;Gate, 1995;Laloux et al, 1980), is probably related to the production features of Mediterranean systems. These are characterized, apart from the Mediterranean climate peculiarities, by the use of the Mediterranean type of wheat that normally has a lower tillering capacity and shorter growing season (Slafer and Whitechorch, 2001).…”

Comparison of Growth and Grain Yield of Spring Wheat in Lhasa, the Tibetan Plateau, with those in Sapporo, Japan

“…In general, total dry weight is increased while harvest index is decreased by a high sowing rate (Ellen, 1990;Stapper and Fischer, 1990). The reduction of harvest index was caused by a lighter grain weight and fewer grains per ear (Ellen, 1990). Compared with the results in Sapporo, grain weight was significantly lower in Lhasa in both cultivars and grain number per ear was signifi cantly lower in Lhasa in one of two cultivars.…”

“…It is possible that a high sowing rate results in a low harvest index in Lhasa in the present study. In general, total dry weight is increased while harvest index is decreased by a high sowing rate (Ellen, 1990;Stapper and Fischer, 1990). The reduction of harvest index was caused by a lighter grain weight and fewer grains per ear (Ellen, 1990).…”