Volume 1 Issue 2
Estimation of yield losses of wheat (Trlticum aestivum L.) caused by little seed canal grass (Phalarls minor Retz.) competition
Author(s): B. DUARY AND N. T. YADURAJU
Abstract: Experiments were conducted in soil typic Ustochrepts (Inceptisol) during winter season of 1997-99 to detennine the
effects of varying densities of little seed canary grass (Phalaris minor Retz.) on the grain yield of wheat. As the
density of weed incre11Sed from 0 to 200/m2 the yield of wheat was reduced by 23.9 and 32.6% in the first and
second year respectively. To predict the yield of wheat, the yield data was fitted to an empirical model based on
hyperbolic relationships over P. minor densities. The obsetved and predicted yield losses were close. The
relationship between wheat and little seed canary grass was also shown by a non-linear regression model based on
relative leaf area of woods estimated in earlier stage. This single parameter model also gave good fit to the data on
yield loss calculated frpm the observed weed free crop yields. From the yield loss-weed density model the economic
threshold of this weed for the herbicide isoproturon was calculated as 13.0 to 19.7 /m2 for the single season.
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