Int.J.Curr.Microbiol.App.Sci (2018) 7(3): 230-241 230 Original Research Article https://doi.org/10.20546/ijcmas.2018.703.027 Relationship of Temperature Based Meteorological Indices with Phenology and Yield Performance of Wheat as Influenced by Sowing Times Bhagat Singh, Mukesh Kumar * and A.K. Dhaka Department of Agronomy, CCS Haryana Agricultural University, Hisar-125004, India *Corresponding author ABSTRACT Introduction Wheat (Triticum aestivum L.) is the second most important staple food crop of the world accounting nearly 30% of global cereal production covering an area of 218.5 million hectare with an average productivity of 3.26 tonnes ha -1 (FAO, 2014). Its area and productivity is increasing rapidly adopting across the globe, due to its wider adaptability sustainability under divers agro climatic conditions (Kumar et al., 2014). Majority of the wheat area in Indo-gangetic plains falls under timely sown irrigated crop conditions, a sizeable area comes under various cropping systems such as rice-wheat, sugarcane-wheat, potato-wheat, vegetable pea-wheat, etc. In these cropping systems, late harvest of preceding crops makes wheat cultivation by farmers delayed resulting in shorter crop period. Among production factors, sowing time and wheat varieties selection are the most International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 03 (2018) Journal homepage: http://www.ijcmas.com Field experiment was conducted during Rabi season of 2010-11 and 2011-12 at Research farm of CCS Haryana Agricultural University, Hisar, India to study agrometeorological indices on phenology and yield of wheat cultivars as influenced by Late, very late sown heat stress condition. The experiment was laid out in split plot design with two sowing time viz., late (16 th Dec.) and very late (5 th Jan.) in main plot and four late sown genotypes (PBW 373, WH 1021, PBW 590 and PBW 550) in sub plots with three replications. On the basis of two years pooled data it was revealed that 16 th Dec. sown wheat took maximum calendar days (129 days), GDD (1546 0 C day), HTU (11421 0 days hour) and PTU (18143 0 days hour) for all the phenophases upto maturity, which got reduced significantly with very late sowing of wheat on 5 th Jan., grain yield and biological yield recorded with 16 th Dec. sown crop were significantly higher by 14.8 and 13.2 percent over very late sowing of 5 th Jan. Among the varieties, PBW 550 was recorded with maximum effective tillers/m 2 (419), highest grain (44.5 q/ha), biological yield (114 q/ha), GY HUE (3.02 kg ha -1 day -1 ) and BY HUE (7.74 kg ha -1 day -1 ). PBW 373 recorded maximum GDD (926 and 1540 0 C day), HTU (6416 and 11689 0 days hour), PTU (10554 and 18222 0 days hour) and PTI (10.2 and 12.7 0 C days day -1 ) upto heading and maturity. Due to very late sowing (5 th Jan.), maximum reduction in grain yield of about 17.1 percent was recorded in PBW 550, followed by PBW 373 (14.7%) and PBW 590 (14.7%) and minimum reduction in WH 1021 (12.5%) as compared to 16 th Dec. sown crop. Keywords Late sown wheat, GDD, PTU, HTU, PTI, HUE, Grain yield Accepted: 04 February 2018 Available Online: 10 March 2018 Article Info