PERFORMANCE OF WHEAT (TRITICUM-AESTIVUM) IN RELATION TO SMALL CANARY GRASS (PHALARIS MINOR) UNDER DIFFERENT LEVELS OF IRRIGATION, NITROGEN AND WEED POPULATION

A 3-year field experiment was conducted during the winter season of 19 86-87 to 1988-89 to evaluate the performance of wheat (Triticum aestiv um L. emend. Fiori & Paol.) under different levels of irrigation, nitr ogen and weed population. It was laid out on a deep, well-drained, san dy-loam soil of Ludhiana, with 18 combinations comprising 2 irrigation regimes based on irrigation water : cumulative pan evaporation (IW:PA N-E) ratio of 0.4 and 0.8, 3 levels of N (80, 120 and 160 kg N/ha) and 3 weed population intensities (0, 40 and 80 plants/m(2)) of small can ary grass (Phalaris minor Retz.). Weed-population intensity of 40 and 80 plants/m(2) decreased the grain yield of wheat by 21 and 23% respec tively. The nitrogen x weed population interaction was not significant . Irrigation regime had no significant effect on the grain yield of wh eat. There was high depletion of soil moisture From the soil profile i n the presence of weeds and higher levels of N.