WATER REQUIREMENT OF WHEAT (TRITICUM-AESTIVUM) AS AFFECTED BY DIFFERENT LEVELS OF IRRIGATION, SEEDING DATE AND FERTILIZER

A field experiment was conducted during winter season of 1992-94 at Ra nchi on sandy-loam soil to estimate tile daily consumptive water use, moisture-extraction pattern, crop coefficient and water-use efficiency of wheat (Triticum aestivum L. emend. Fiori & Paol.) under different levels of irrigation, seeding date and fertilizer. The crop irrigated at crown-root initiation, maximum tillering, boot and milk stages cons umed 346.6 mm water to produce 3 187 kg grain/ha with water- use effic iency of 9.2 kg grain/ha-mm water. Daily water use and surface soil-mo isture extraction increased with incl ease in irrigation frequency. Th e crop receiving 4 irrigations had higher seasonal (0.63) as well as m onth-wise crop coefficient with its peak (0.96) in January than that r eceiving either 2 (crown-root in itiation and boot) or 3 (crown-root i nitiation, boot and milk) irrigations. Timely-sown wheat (24 November) used 2.84 mm water/day to produce 3 185 kg grain/ha in 118 days with water-use efficiency of 9.49 kg/ha-mm. Peak water-use rate (mm/day) co incided with flowering stage of wheat, which was attained during first week of February in timely-sown and during last week in late-sown (18 December) crop. Highest crop coefficient was recorded in January (1.0 ) for timely-sown and in February (0.76) for late-sown crop. Wheat wit h recommended fertilizer(N, P and K (a) 100, 22 and 21 kg/ha respectiv ely) utilized 2.79 mm water/day to produce 3 140 kg grain/ha in 115 da ys with water-use efficiency of 9.8 kg/ha-mm water. Higher seasonal an d month-wise crop coefficient of wheat was recorded with recommended f ertilizer (N100P22K21) than with its half dose (N50P11K10.5).