RESPONSE OF WHEAT (TRITICUM-AESTIVUM) VARIETIES TO DIFFERENT DATES OFSOWING

A field experiment was conducted during the winter season of 1988-89 t o study the heat tolerance of 10 varieties (HI 977', 'HI 1116', 'HI 11 23', 'HD 2270', 'HD 1558', 'GW 120', 'Sonalika', 'Lok 1', 'RHR 2825' a nd 'GIPSI 260') of wheat (Triticum aestivum L. emend. Fiori & Paol.) i n terms of phenological development, grain yield and its components, u nder 3 dates of sowing (15 November, 15 December and 15 January) in ir rigated condition. Increased temperature significantly reduced the day s of anthesis, maturity duration and flag-leaf area Likewise, higher p ost-anthesis temperature, ie 26.6-30.6 degrees C, contributed to decli ne in productive number/ear, biological yield, 1000-grain weight and g rain yield under late sowing compared with normal sowing. Relative dec line in these attributes due to suboptimal temperature was lesser in ' HD 2279', 'HI 1116', 'DW 120','Sonalika' and 'Lok 1', enabling them to perform better under high temperature on late sowing. Coefficients of correlation of grain yield showed significant positive relationship w ith effective ear number,biological yield and 1000 - grain weight, ind icating their involvement in heat tolerance of wheat under late-sown c ondition.