Some effects of leaf posture on the yield and water economy of winter wheat

Abstract

Selections for erect-(E) and lax-leaf (L) posture in winter wheat were made from a cross between parents which contrasted in the character. By the F5 generation there were consistent, heritable differences between E and L lines. The lines were evaluated in three field experiments and a glasshouse experiment.In an experiment in which plots were automatically sheltered from rain and in which there were three irrigation treatments, there was no treatment-posture interaction, and over all treatments E lines outyielded L lines by 0·26 t/ha. When fully irrigated the water use of both E and L lines between 1 May and maturity was approximately 280 mm. Withholding water caused a reduction in water use and a corresponding reduction in grain yield for both E and L lines.When the four most erect- and the four most lax-leaved lines were considered over all three field experiments, E lines maintained a slight, though not significant, grain yield advantage of 0·17 t/ha over L lines. However, the E lines produced significantly more biomass, averaging 0·7 t/ha more than L lines, and this extra biomass was not produced at the expense of additional water requirement. However, results from the glasshouse experiment suggested that the E lines may be more susceptible to a substantial pre-anthesis drought.It is concluded that varieties of winter wheat with the erect-leaf habit may provide an opportunity of increasing biomass production. In an environment in which a preanthesis drought is unlikely to occur, such varieties may give the highest yields. However, on light soils prone to early drought or at sites which would not permit the maximum expression of leaf area index at anthesis, varieties with a lax-leaf posture may give greater yield.