EFFECT OF NITROGEN NUTRITION ON GROWTH, YIELD AND RADIATION USE EFFICIENCY OF DIFFERENT WHEAT (Triticum aestivum L.) CULTIVARS

Optimal nitrogen nutrition exercises a strong effect on wheat (triticum aestivum l.) growth and yield attributes. to investigate the possible role of nitrogen fertilizer on yield and yield contributing attributes of different wheat cultivars, a field experiment was planned on sandy clay loam soil during 2006-07. three wheat cultivars (as-2002, bhakar-2002, inqlab-91) were selected as test crop and were treated with different nitrogen fertilizer inputs viz. (control, 90, 120, 150, 180) kg n ha^-1. the results showed that nitrogen fertilization had a significant effect (p ≤ 0.05) on wheat yield and yield components but germination count, and spike length, remained unaffected at varying levels of nitrogen. among cultivars (as-2002, bhakar- 2002, inqlab-91), as-2002 cultivar along with nitrogen treatment 120 kg n ha^-1 resulted in maximum grain yield (6353 kg ha^- 1) and harvest index (43.11%) due to enhanced number of spike bearing tillers (395.3), 1000-grain weight (48.57 g) and photosynthetic active radiation (815.0 g mj^-1). plant height (92.33 cm), straw yield (9348 kg ha^-1), biological yield (15390 kg ha^-1) and radiation interception (813.6 g mj^-1) increased with increasing levels of nitrogen application compared to the control, but further increment beyond 120 kg ha^-1 in nitrogen input did not affect the yield. the highest mean values of rue on tdm (18.95 g mj^-1) and grain yield basis (7.91 g mj^-1) were observed when as-2002 cultivar treated with nitrogen level of 120 kg ha^-1 and 150 kg ha^-1. all the cultivars exhibited poor response when supplemented with 90 kg n ha^-1. in conclusion, 120 kg n ha^-1 proved to be the best rate for higher grain yield of as-2002 cultivar.