Salt Tolerant Gossypium hirsutum L. Cultivars are Mostly Long-Staple Length Cultivars

Background: Cotton is a major cash crop in the global and, in particular, the Indian markets, playing an important economic role in the textile and oil industries. The cotton plant is one of the highly bred plants that is highly sensitive to salt stress. As cotton is a non-food crop, the availability of non-saline terrain and water for the cultivation of cotton plants is only next to other food crops, thereby posing a need to better understand the salt tolerance of this plant. Gossypium hirsutum L. cultivars MCU 5, LRA 5166, and SVPR 2 were selected based on exomorphic traits like staple length and cropping season so that the genotypic responses to salt stress and salt shock can be compared for interpreting the effects of salinity on in vitro germination. Thus, this study aims to establish genotypic dependence on salinity tolerance. Results: The results affirmed genotypic variation in salinity tolerance, with MCU 5 tolerating salt stress better than LRA 5166 and SVPR 2 in all the observed stages of growth of the plant and the parameters measured. Further salt-tolerant cotton varieties were observed to be long-staple length varieties; staple length is the fiber character of the cotton lint. Moreover, salt tolerance in the vegetative growth stage of cotton plants is not independent of the germination stage of the plant.Conclusion: Nevertheless, the correlation of genotypic dependence to morphological characteristics, in particular, staple length (and cropping season), is of agronomic and commercial significance. Further research by screening and investigating a greater number of cultivars using biochemical and molecular techniques will provide a better understanding of this observed phenotypical relationship to the genotypes of cotton cultivars under salt stress.

Analyzing Quantitative Trait Loci for Fiber Quality and Yield-Related Traits From a Recombinant Inbred Line Population With Gossypium hirsutum Race palmeri as One Parent

Fiber quality and yield-related traits are important agronomic traits in cotton breeding. To detect the genetic basis of fiber quality and yield related traits, a recombinant inbred line (RIL) population consisting of 182 lines was established from a cross between Gossypium hirsutum cultivar CCRI35 and G. hirsutum race palmeri accession TX-832. The RIL population was deeply genotyped using SLAF-seq and was phenotyped in six environments. A high-density genetic linkage map with 15,765 SNP markers and 153 SSR markers was constructed, with an average distance of 0.30 cM between adjacent markers. A total of 210 fiber quality quantitative trait loci (QTLs) and 73 yield-related QTLs were identified. Of the detected QTLs, 62 fiber quality QTLs and 10 yield-related QTLs were stable across multiple environments. Twelve and twenty QTL clusters were detected on the At and Dt subgenome, respectively. Twenty-three major QTL clusters were further validated through associated analysis and five candidate genes of four stable fiber quality QTLs were identified. This study revealed elite loci influencing fiber quality and yield and significant phenotypic selection regions during G. hirsutum domestication, and set a stage for future utilization of molecular marker assisted breeding in cotton breeding programs.

Economic Analysis of Parawilt Management in Bt-Cotton (Gossypium hirsutum L.) in Mansa District of South-western Punjab, India

Parawilt characterized by a sudden drooping of leaves followed by death of plants withinfew hours after rainfall or heavy irrigation has been the major physiological disorder affectingproductivity of Bt-Cotton (Gossypium hirsutum L.). We studied the effect of foliarapplication of cobalt chloride (@10 mg L-1 water) within 24-36 hours after appearance ofsymptoms on recovery rate, seed cotton yield and economics at farmers’ fields in Mansadistrict of south-western Punjab. The results of front line demonstrations revealed thatfoliar application of cobalt chloride resulted in significantly (p<0.05) higher seed cottonyield by ~9.1 per cent, compared with the control (no-spray). The mean gross returns(MGRs) increased significantly by Rs. 9620/- ha-1 in the demonstration plots. The higherbenefit-cost (B:C) ratio of 2.38 was observed for the demonstration plots, against 2.15 forthe control (no-spray). The foliar application of cobalt chloride resulted in higher averageproduction efficiency of 1.1 kg seed cotton yield ha-1 d-1 and average economic efficiencyof Rs. 65.7 ha-1 d-1, compared with the control. These results therefore, revealed that farmerscan effectively manage parawilt in Bt-cotton using foliar application of cobalt chloride andmay increase seed cotton yield and economic returns.