CROP PERFORMANCE, NUTRIENT UPTAKE ,NITROGEN USE EFFICIENCY AND HARVEST INDEX OF WHEAT (TRITICUM AESTIVUM) GENOTYPES AS INFLUENCED BY DIFFERENT SOWING DATES UNDER TEMPERATE KASHMIR AND ITS VALIDATION USING CERES MODEL

A field experiment was conducted on silty clay loam soil during the rabi 2003-04 and 2004-05 to study the effect of dates of sowing on performance, nutrient uptake, N use efficiency and harvest index of N and simulation study of nitrogen availability of different genotype of wheat under temperate Kashmir. Wheat cultivar HS 240 and SKW 191 exhibited the highest grain yield of 4.28 and 5.50 t/ha and 4.39 and 5.38 t/ha in early date of sowing (1 October) respectively in both years of study.  However grain yield of all genotypes of wheat was higher in 2004-05 due to prevailing favourable weather conditions for higher grain production. In temperate region, nutrient (NPK) uptake by different genotypes of wheat significantly decreased by delaying sowing from 1 to 30 October. The highest uptake of NPK in grain and straw was recorded by Cultivar HS 240 and HS 295, respectively.  N Use efficiency (NUE) and N Harvest Index (NHI) were the highest (43.81 kg grain/kg N uptake  and 73.84%) in 2003-04 and 41.82 kg grain/kg N uptake and 73.15% in 2004 -05  with 30 October sowing of wheat. However, the maximum NUE of 43.68 kg grain /kg N uptake with NHI of 72.7 % was recorded by Shalimar wheat-1 and the minimum NUE of 38.79 kg grain /kg N uptake with NHI of 65.75 % by HS 295 during the year 2004-05,respectively. Simulation study indicated that the variation in simulated N uptake over observed value ranged from 1.46 to 43.47 % and the highest simulated grain yield of wheat (6.30 t/ha) was recorded at higher dose of 200 kgN/ha in early sowing (1 October) and decreased to 4.87 t/ha and 4.31 t/ha at 15 and 30 October sowing dates with same dose.