Abstract
The investigation was carried out in focusing the genetic variability for different traits of wheat influenced by heat tolerance mechanism to find out relationships among phenological, physiological and yield contributing traits. Spring wheat cultivar of 25 genotypes were selected and cultivated under late sowing condition at the Regional Wheat Research Institute, Shympur, Rajshahi, Bangladesh from December, 2016 to April, 2017. Significant variability among the genotypes exposed for different traits related to heat tolerance. Results showed that the genotypes G24, G10, G01, G13, G16, G25 and G14 ranked as better category considering maximum number of traits in mean performance indicating their tolerance to heat stress under late sowing condition. Phenotypic variances (σg2) of all traits were greater than those of genotypic variances (σg2). The same trends were also found in their co-efficient of variances. The phenotypic co-efficient of variances (PCV) of all traits were greater compare to those of genotypic co-efficient of variances (GCV) and their values were closer to each other. The heading days (HD), canopy temperature at vegetative stage (CTvg), canopy temperature at grain filling stage (CTgf), biomass, plant height (PH), spike/m2 (SPM), spikelet/spike (SPS), grain/ spike (GPS), thousand grain weight (TGW) and yield exhibited higher heritability (hb2) estimated under irrigated late sowing (ILS) condition. Under the same ILS condition SPAD, SPM, SPS, GPS, TGW and yield showed moderate to high genetic advance (GA) obtained through computing their mean percentage (%) and the rest traits HD, maturity days (MD), CTvg, CTgf, biomass, PH and harvest index (HI) exposed smaller genetic advance (% mean). The co-efficient of variation (CV%) of all attributes in all genotypes were significantly lower (1.36 - 6.96). Both heritability and genetic advance were found lower for MD, SPAD and HI indicated their non additive genetic effects for which these traits might not be recommended for selection. However, spike/m2, spikelet/spike, grain/spike, thousand grain weight and yield belonged to higher heritability and high to moderate genetic advance in mean percentage (%) along with wide genetic variation and lower environmental influence in heat stress situation indicated the most likely heritability due to the effects of additive genes that might be suggested as effective process of selection for these traits in heat stress condition.
Highlights
Wheat (Triticum aestivum L.) is one of the most widely grown cereal crop that plays an important role in world food security
Under the same irrigated late sowing (ILS) condition SPAD, SPM, SPS, GPS, thousand grain weight (TGW) and yield showed moderate to high genetic advance (GA) obtained through computing their mean percentage (%) and the rest traits heading days (HD), maturity days (MD), canopy temperature at vegetative stage (CTvg), canopy temperature at grain filling stage (CTgf), biomass, plant height (PH) and harvest index (HI) exposed smaller genetic advance (% mean)
The objectives of this study were to examine the performance of wheat genotypes in late sowing condition, estimate the variability, heritability, genetic advance, identify heat tolerant genotypes for hybridization program expecting to provide superior segregates
Summary
Wheat (Triticum aestivum L.) is one of the most widely grown cereal crop that plays an important role in world food security. It occupies the second position among the cereals next to rice and it ensures a vital role in the food security of teeming hungry millions of people of Bangladesh. The average wheat yield of the world will have to increase during the coming 25 years from 2.6 to 3.5 tones ha−1 [1]. This is very much essential to maintain global food security that requires a continuing supply of improved germplasm with regard to climate change bringing global warming. Under the changing climatic conditions, heat stress is one of the major challenges for wheat production
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