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Drought is a devastating factor for crop production worldwide. Therefore, an experiment was conducted to study genetics for some agro-physiological traits in cotton under drought stress. The 13 parental cotton genotypes along with their 30 F1 hybrids were planted under normal and drought conditions. The mean performance of the genotypes was assessed through principal component and heat map analyses. The principal component analyses revealed 53.99 and 53.15% in the first two principal components of variability for normal and drought conditions, respectively. Heat map analysis revealed that three cotton genotypes i.e. FH-207 × NS-131, FH-207 × KZ-191 and S-15 × AA-703 attained higher values for all the traits except for canopy temperature under drought conditions. These crosses may proliferate to further filial generations to identify transgressive segregates for drought tolerance. The heritable differences of F̅1 and mid-parent showed dominance and non-additive gene action under drought conditions. Heritable differences between F̅1 and P̅1 showed over dominance and partial dominance under drought conditions. Heritable differences between F̅1 and P̅2 indicated negative over dominance and partial dominance for all traits under drought conditions. Proline contents and the bolls per plant showed high heritability and genetic advance through additive gene action. Therefore, these two traits can be used as a means of selection in future breeding programmes of drought tolerance.

Drought stress negatively affects the cotton production all over the world. The negative impact of drought varies for different species due to some morphological and root attributes that help some species to better stand under drought. But the extent of disturbance varies for different cotton species. To find out such variation, two cotton species (Gossypium hirsutum and Gossypium arboreum) were studied under normal and drought conditions for 2 years. Two genotypes for each species were included, i.e. PC-1 and COMILLA (G. arboreum) and IUB-13 and IUB-65 (G. hirsutum). The experiment was laid out under a completely randomized design following factorial arrangement. Genotype × treatment × year interaction of cotton genotypes was studied for different root, morphological, physiological and fibre-related traits. Traits such as above ground dry biomass, above ground fresh biomass, chlorophyll contents, leaf area, seed cotton yield, sympodial branches/plant, fibre strength and ginning out-turn were higher in G. hirsutum genotypes as compared to G. arboreum genotypes. However less reduction under drought in all above mentioned traits was recorded for G. arboreum, than G. hirsutum. Furthermore, root traits; primary root length, lateral root numbers, root fresh weight and root dry weight were enriched under drought condition in G. arboreum genotypes than in G. hirsutum genotypes, which is a clear manifestation of higher drought tolerance ability in G. arboreum genotypes transferrable to G. hirsutum genotypes through interspecific crossing or other means.

Salt tolerance is a physiologically and genetically complex trait controlled by multiple genes. To analyze the genetic basis of salt tolerance we evaluated 18 F 1 along with their nine parents under three salt stress levels i.e. control, 10 dS m −1 and 15 dS m −1 in the summer of 2017 and 2018. Data were recorded for the number of bolls, seed cotton yield, boll weight, Na + , K + , K + /Na + ratio, H 2 O 2 , SOD, POD, CAT and TSP. Line × tester analysis indicated that the contribution of lines was greater than testers. Except for Na + , most of the traits were controlled by non-additive genes. With the rise of salt stress, SCA variances increased and were higher than GCA variances for most of the traits indicating the traits were controlled by a few largely dominant genes. KEHKSHAN, FH-118 and FH-114 were found good general combiner whereas the cross KEHKSHAN × FH-114 was a good specific combiner and also indicated significant better parent heterosis for most traits during two years under salt stress and can be utilized in a breeding programme for salt tolerance.

Short duration cotton (Gossypium hirsutum L.) cultivar may be more profitable for the growers, as it will have shortened critical growth window for drought, heat and insect pests. Therefore, in the present research work, two cotton advance lines IUB-71 and IUB-73 along with an approved cotton cultivar IUB-13 were tested under four different sowing dates i.e. S1 (25th April), S2 (10th May), S3 (25th May) and S4 (10th June) in 2017 and 2018 under field condition. Field layout was RCBD factorial with four sowing dates as one factor and three cotton genotypes as another factor with three replications. Data were recorded for plant height, total number of nodes, bolls per plant, seed cotton yield (SCY), above ground fresh biomass (AGFB) and harvest index (HI). An overall decreasing trend with increasing sowing dates was observed in all the traits except HI that relatively increased in all the three genotypes. Within each sowing date, a higher value for each trait was observed for genotype IUB-73 except for AGFB might be due to higher reproductive allocation. It is concluded that IUB-73 due to superior SCY and HI specifically under late planting is best fit for short cotton seasons with reduced critical window for cotton management.

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