THERMAL REQUIREMENTS OF WHEAT UNDER DIFFERENT GROWING ENVIRONMENTS OF TARAI REGION (UTTARAKHAND)

摘要

Temperature is one of the most important elements of the climate which determines the potential productivity level particularly for winter crops. Heat unit requirement or growing degree days (GDD) has been used for characterizing the thermal response in wheat crop. The quantification of heat use efficiency (HUE) is useful for the assessment of yield potential of a crop in different growing environments. A field experiment was carried out during Rabi season of 2007-08 and 2008-09 at the Crop Research Centre (CRC) of G. B. Pant University of Agriculture & Technology, Pantnagar to quantify GDD requirement of different phenophases of wheat with two genotypes as influenced by three sowing dates. Pantnagar is situated at 29 deg N latitude, 79.3 deg E longitude and at an altitude of 243.8 m above mean sea level. The area lies in the 'Tarai' belt located in the foot hills of Himalayas. The area falls under sub-humid subtropical climate with an annual rainfall about 1400 mm, out of which 80 percent is received during SW monsoon. The studies revealed that the wheat sown on 20 November, accumulated higher number of GDDs and low PTI with higher HUE, among the genotypes tried. In case of PBW-343 higher GDD was recorded followed by WH-542 during almost all the phenophases of wheat for the year 2007-08 and the trend was also similar during the year 2008-09. Among the sowing dates, crop sown on 09 January accumulated higher PTI for PBW-343 over WH-542 during the study period. The HUE value was highest for the crop sown on 20 November with genotype PBW-343; it decreased with the delayed sowings. Among the sowing dates, higher grain yield was observed with low value of PTI for the crop sown on 20 November during both the years. High value of HUE gave good yield and it decreased with the delayed sowing.