Comparative performance of different crop production functions for wheat (Triticum aestivum L.)

Summary

Experiments were conducted for wheat (Triticum aestivum L.) grown in the lysimeters with controlled irrigation at Berlin (FRG) and in field plots at Hisar (India) under different climatic conditions. Crop production functions, relating crop yield with evapotranspiration with and without the consideration of the time of water deficit during crop growth period, were derived. The derived functions and those previously obtained by different workers were tested against the experimental data. There was a significant correlation of seasonal evapotranspiration with yield that was slightly higher for dry matter than for grain. The correlation, which was quite high for linear functions, was slightly greater for nonlinear functions. The correlation was also slightly improved if evapotranspiration for different growth stages was considered rather than total seasonal evapotranspiration. Since there apears to be no single equation that fits all of the conditions studied and since different equations lead to different conclusions, it is suggested that the crop production functions considering evapotranspiration at different growth stages be used with caution. In general the degree of sensitivity of grain yield and dry matter yield to water stress for wheat cultivar WH 283 grown in field experiments under semi-arid climate decreased in the order of crop growth sub-periods I (Sowing to heading), III (Milk ripe to ripe), and II (Heading to milk ripe). However, the sensitivity of the grain yield and dry matter yield to water stress for wheat cultivar Kolibiri grown in lysimeter experiments under humid climate decreased in the order of the growth sub-periods i.e. I, II, and III.