Division of Agronomy, Indian Agricultural Research Institute, New Delhi-liD 012, India.
Present Address:1 Division of Agronomy, College of Horticulture, KAU P.O. Thrissur, Kerala-680 656, India.
Experiments were conducted to determine the effects of varying density of winter wild oats [Avena sterilis ssp. ludoviciana (Dur.) Nym.] on the grain yield of wheat (Triticum aestivum L.). The grain yield of wheat was reduced as wild oat density increased through the reduction in fertile tillers, spike length, grains per spike and test weight of grains. To predict the yield of wheat, the yield data were fitted to an empirical model based on hyperbolic relationships over wild oat densities. The observed and predicted yield losses were more or less similar. However, parameters estimated varied between years. The relationship between wheat and wild oats was also described by a non-linear regression model based on relative leaf area of weeds estimated shortly after sowing. This single parameter model also gave a good fit to the data on yield loss calculated from the observed weed free crop yields.
