EFFECT OF LEVELS OF NITROGEN ON WHEAT AS INFLUENCED DATE OF SOWING

摘要

Field experiments were conducted at Indian Agricultural Research Institute, New Delhi during 1992-1993 and 1993 -1994 to study the effect of sowing date on the response of wheat to nitrogen. Results indicated that delay in sowing from November 16 to December 16 resulted in a significant reduction in plant height, number of tillers and earhead/m in row length, earhead length, number of grains/earhead and test weight, which led to a significant reduction in grain and strawyield of wheat. Delay in sowing from November 30 to December 16 reduced the grain yield by 8 per cent, whereas further delay in sowing from December 16 to December 31 reduced the grain yield by 19 per cent. Nitrogen application significantly increased growth and yield attributing characters which led to a significant increase in grain and straw yield of wheat particularly in late sown crop At 120 kg N/ha delay in sowing from November 30 to December 16 did not cause a reduction in grain yield. Late sown crop required more nitrogen; economic optimum dose of nitrogen for December sown crop was about 100 kg N/ha against 80 kg N/ha for November sown crop. The response to nitrogen at economic optimum dose was higher in late sown wheat; about 20 kg grain/kg N in December sown crop against17 kg grain/kg N in November sown crop Both agronomic efficiency and apparent recovery of fertilizer nitrogen were also higher in late sown wheat. The adverse effect of delayed sowing could be mitigated to some extent by application of higher dose of nitrogen.