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Uncertain heat shock by a rapid increase in temperature particularly at the critical growth stage affects plant productivity. The study aimed to assess qualitative changes in wheat grains when plant exposed to high temperature shock (HTS) at starting anthesis for limited durations (48, 72 and 96h). Selected wheat cultivars (Pirsabak-2005, Pakhtunkhwa-2015, Pakistan-2013, DN-84, P-2, P-12 and P-18) were exposed to extending HTS effective from anthesis in the field covering plants within plastic tents for a limited duration. The experiment was conducted in 2017-18 and 2018-19 at the Research Farm, the University of Agriculture Peshawar, Pakistan in a randomized complete block design, in three replications. Temperatures inside and outside plastic tents were manually noted. Two years mean data showed significant effects of HTS on the wheat grain quality. Imposed HTS for 48, 72 and 96h resulted in a reduction on grain amylose by 23, 39 and 48% and wet gluten by 16, 25 and 36%, respectively when compared with the control (i.e. no HTS). Contrary to this, as compared to the control treatment an increase noted in the grain amylopectin by 7, 11 & 17% and in the grain N-content by 13, 28 & 41% with imposing HTS extending to a duration of 48, 72 and 96h, respectively. The study concluded adverse effects of HTS at the anthesis stage on wheat grain quality disturbing amylose and amylopectin ratios, which latter on brought changes in floor structure and gluten elasticity. However, cultivar did differ to respond to the changes but have the option to choose the best one.

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Eight Brassica napus L. genotypes including Rainbow, Rustam Canola, Dunkled, Abasin-95, NIFA Gold, Durr-e-NIFA, Punjab Sarsoon and Faisal Canola, varied by genetic makeup and yield traits were crossed during 2014-15 in a 8 × 8 complete diallel fashion at the University of Agriculture, Peshawar, Pakistan. Parental genotypes and their 56 F1 hybrids were sown during 2015-16 in a randomized complete block design to evaluate through mean performance, heterosis and combining ability effects. Significant (p≤0.01) differences were observed among the parental genotypes and their F1 hybrids for all the studied traits. The F1 hybrids NIFA Gold × Rustam Canola, Rustam Canola × Punjab Sarsoon and Punjab Sarsoon × Abasin-95 exhibited best mean performance and maximum mid-and better-parent heterosis for plant height, 1000-seed weight and seed yield per plant. Combining ability analysis revealed significant (p≤0.01) mean squares due to general (GCA), specific (SCA) and reciprocal combining ability (RCA) for all the traits indicating the importance of additive, non-additive and maternal effects. For plant height and main raceme length, the mean squares due to GCA were greater in magnitude than SCA and RCA. However, for 1000-seed weight and seed yield per plant, the mean squares due to RCA were found greater followed by SCA and GCA. Results further enunciated that due to the preponderance of GCA and RCA effects, the contribution of additive and maternal effects was more important in the expression of these traits. Parental genotypes Abasin-95 and Punjab Sarsoon were found as best general combiners and performed better in combination with other genotypes for the majority of the traits. The F1 hybrids NIFA Gold × Rustam Canola, Rustam Canola × Punjab Sarsoon, Punjab Sarsoon × Abasin-95 and Dunkled × Rainbow exhibited best mean performance and renowned SCA for yield traits. The variances due to σ 2 SCA were higher than σ 2 GCA and σ 2 RCA. The ratios of σ 2 GCA/σ 2 SCA were noted to be less than unity which revealed that all the traits were controlled nonadditively and hence, the delayed selection in later segregating generations might be more effective. Based on the GCA and SCA effects and mean performance, the promising parental genotypes and F1 hybrids could be further utilized in future breeding programs to develop the rapeseed genotypes with good yield potential and oil quality traits.