Vol. 11, Special Issue 12 (2022)

Author(s):
Shivani Thakur, Ranbir Singh Rana and Sandeep Manuja

Abstract:
A field experiment was conducted during kharif seasons of 2017 and 2018 to study the accumulated growing degree days (GDD), helio-thermal unit (HTU), photo-thermal unit (PTU), heat use efficiency (HUE) at different phenological stages and performance of rice (Oryza sativa L.) varieties. The treatment consisted of three cultivars with five dates of transplanting viz, 15^th June, 25^th June, 5^th July, 15^th July and 25^th July in Factorial RBD. The transplanting window selected was having 1- 3 °C change in temperature. Results of present study revealed that the crop transplanted on 15^th June acquired maximum growing degree days, photo-thermal unit and helio-thermal unit for tillering, panicle initiation, 50% flowering and physiological maturity which was significantly reduced with subsequent delay in the transplanting time. The grain yield recorded in 15^th June (5713 kg ha^-1) was statistically at par with 25^th June yield (5315 kg ha^-1) and with further delay in transplanting date there was reduction in yield. The per cent decrease in grain yield of 25^th July transplanting over 15^th June transplanting was about 40 to 45%. Among the varieties, the grain yield of variety HPR 2143 was maximum (5002 kg ha^-1) followed by HPR 1068 (4682 kg ha^-1) and HPR 2880 (3993 kg ha^-1).