STUDY OF SENESCENCE DEVELOPMENT IN SPRING WHEAT (Triticum aestivum L.) UNDER HEAT STRESS CONDITION

Abstract

Two field experiments were conducted at research farm of Wheat Research Centre, Dinajpur (25°38´ N, 88°41´ E and 38.20 m above sea level), Bangladesh, during wheat season of 2015-16. Expt. 1: Fifty seven advanced lines compare with check varieties BARI Gom-21 (Shatabdi), BARI Gom-26 and BARI Gom-30 and Expt. 2: Forty five advanced lines compare with check varieties BARI Gom-21 (Shatabdi), BARI Gom-26 and BARI Gom-30. And each of the experiments consist of two time of sowing, the first one was sown on optimum 19 November called irrigated timely sowing (ITS) and the second was sown in 24 December 2015 was late sown condition named irrigated late sowing (ILS) in an alpha-lattice design with two replications to evaluate the senescence rate of genotypes under optimum and late sown condition and to find out the suitable time of sowing for wheat genotypes. The present study found that 1000-grain weight of wheat genotypes in exp.1 under ITS condition ranged from 39.00 to 62.00g with mean 49.58, while it ranged from 33.00 to 54.00g with mean 43. in ILS condition. Similar results of 1000-grain weight were also observed in exp. 2. The grain yield of wheat genotypes in exp. 1 under ITS condition ranged between 3.03 to 6.93 ton ha-1 and mean 4.67, whereas it ranges from 2.33 to 4.62 ton ha-1 with the mean of 3.53 ton ha-1 in ILS condition. Equally results of grain yield were also observed in exp. 2. Senescence rate of wheat genotypes in exp. 1 under ITS condition ranged from 1.74 to 6.81% SR with mean 4.43 % SR, but it ranged from 1.94 to 7.19 % SR with the mean 5.24 SR in ILS condition. Comparable result of senescence rate of wheat genotypes in exp. 2 was recorded as in exp. 1. Heading days had positively correlation with senescence rate (SR) and no correlation with yield, but heading days had significant and negatively correlated with both SR and yield under ILS condition. Maturity days and spikelet per spike were significant and positively correlated under ITS condition and no correlation under late sowing condition. Results showed that the optimum sowing date had higher number of spike per meter square, spikelet per spike, 1000-grain weight and grain yield. Grain yield of 19th November sowing dates is significantly higher than that of 24th December sowing dates. Low grain yield resulted from stress is caused by higher temperatures that prevailed during grain filling; despite senescence rate was increased under late sowing (ILS) condition due to the temperature shock.