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.