Heat-unit requirement for phenological development of wheat (Triticum aestivum) under different levels of irrigation, seeding date and fertilizer

Abstract

A field experiment was conducted during winter season of 1992-93 and 1993-94 at the university farm, Ranchi. to estimate the heat-unit requirement for phonological development of wheat (Triticum aestivum L. emend. Fiori & Paol.) under different irrigation, seeding date and fertilizer levels on sandy-loam soil. Wheat crop irrigated at crown-root initiation, maximum tillering, boot and milk stages (4 irrigations) required more days for onset, duration and heat units for expression of various phenophases, than the crop irrigated either at crown-root initiation and hoot (2 irrigations) or at crown-root initiation, boot and milk stages (3 irrigations). Timely seeded (24 November) wheat required 5, 6, 7, 8, 9, 10 and 10 more days for the onset of flag-leaf emergence, boot, spike emergence, flowering, milk, soft dough and maturity respectively than late-sown (18 December) crop. However, a fixed amount of heat units was needed to proceed from one phenophase to the other, irrespective of the seeding time. Wheat fertilized with recommended dose (N100P22K21) prolonged the onset and duration of phenophases and consequently required more heat units than that fertilized with half this dose.