Genetics of biochemical attributes regulating morpho-physiology of upland cotton under high temperature conditions

Background Cotton is a strategically important fibre crop for global textile industry.It profoundly impacts several countries’industrial and agricultural sectors.Sustainable cotton production is continuously threatened by the unpre-dictable changes in climate,specifically high temperatures.Breeding heat-tolerant,high-yielding cotton cultivars with wide adaptability to be grown in the regions with rising temperatures is one of the primary objectives of modern cotton breeding programmes.Therefore,the main objective of the current study is to figure out the effective breed-ing approach to imparting heat tolerance as well as the judicious utilization of commercially significant and stress-tolerant attributes in cotton breeding.Initially,the two most notable heat-susceptible(FH-115 and NIAB Kiran)and tolerant(IUB-13 and GH-Mubarak)cotton cultivars were spotted to develop filial and backcross populations to accom-plish the preceding study objectives.The heat tolerant cultivars were screened on the basis of various morphological(seed cotton yield per plant,ginning turnout percentage),physiological(pollen viability,cell membrane thermostabil-ity)and biochemical(peroxidase activity,proline content,hydrogen peroxide content)parameters.Results The results clearly exhibited that heat stress consequently had a detrimental impact on every studied plant trait,as revealed by the ability of crossing and their backcross populations to tolerate high temperatures.However,when considering overall yield,biochemical,and physiological traits,the IUB-13×FH-115 cross went over particularly well at both normal and high temperature conditions.Moreover,overall seed cotton yield per plant exhibited a posi-tive correlation with both pollen viability and antioxidant levels(POD activity and proline content).Conclusions Selection from segregation population and criteria involving pollen viability and antioxidant levels concluded to be an effective strategy for the screening of heat-tolerant cotton germplasms.Therefore,understanding acquired from this study can assist breeders identifying traits that should be prioritized in order to develop climate resilient cotton cultivars.

Breeding Enrichment of Genetic Variation of Grain Yield and Its Attributes in Bread Wheat under Drought Stress and Well Irrigation

Drought stress(DS)is one of the most critical environmental abiotic stresses for wheat production in the arid environments.Selection of high-yielding genotypes tolerant to DS can play a significant role in mitigation the negative impacts associated with DS.In the present study,generation means analysis(GMA)was used to study the performance of two crosses under well irrigation(WI)and deficit irrigation[cross I(Line 44×Shandweel-1)and cross II(Line 20×Sakha 93)].Significant differences were observed for days to heading(DH),days to maturity(DM),plant height(PH),spike length(SL),number of spikes per plant(NS/P),number of grains per spike(NG/S),thousand-grain weight(TGW),grain yield per plant(GY/P),and proline content(PC)in the six populations of the two crosses within each irrigation level.Cross II had early maturity and the highest PC,NS/P,TGW,and GY/P regardless of the irrigation level.Cross I showed positive significant relative heterosis and heterobeltiosis for GY/P under the two irrigation levels.The inheritance of characters of cross I revealed additive,dominant,and epistatic effects,which varied with trait and stress.Additive genetic effects predominated in DH,SL,and PC,while non-additive were found in DM,NS/P,NG/S,and GY/P.Narrow-sense heritability estimates(h^(2) n)were high for DH and PC,moderate to high for PH and SL,moderate for DM,NG/S,NS/P,and TGW,and low for GY/P.Based on different drought indices the populations BC_(1),BC_(2),F_(1),and P1 of cross II and BC1 of cross I were more tolerant to drought stress.Therefore,PC,TGW and DH can be used as selection indicators to improve wheat for drought tolerance in early generations and other yield components traits in late generations.The second cross(Line 20×Sakha 93)shows promise and is of interest to a drought tolerance breeding program,where wheat breeders can use recombinant breeding strategies to construct desirable drought stress genes.Correlation and path coefficient revealed that TGW and PC were the main contributor in grain yield in both environments.