Year: 2014
Type: article
Abstract: The main objective of the current investigation was to introduce a rapid genetic assay for testing cotton (G.barbadense) genotypes to endure the late planting conditions.A set of properly selected nine divergent lines was crossed in a 5X4 Factorial-mating design II fashion.Parental lines and their 20 F 2 crosses were evaluated for growth-based and yield-based earliness traits in two divergent planting dates (Middle march, D 1, and Middle May, D 2 ) at Cairo University Experimental Station in the summer seasons of 2010 through 2012.The parental genotypes G90 (cultivar; =39.70g/plant, =0.49), PS6( andG75 ( were identified as late planting (LP) stress tolerant.They showed a high yield potential in late planting and possessed a low to moderate LP susceptibility index "S".Genotypes G90, EC2, PS6 and PS7 were identified as high earliness index stress tolerant.The "S" values based on seed cotton (SC/P) revealed that the cross combinations G86 x G75 (4), G90x G75 (12), G80 x PS7 (18), and G80 x G83 (19) were moderate LP stress tolerance.These crosses showed the highest yield potential at D2. Cross combinations EC1 x PS6, G90 x PS7, EC2 x PS6, EC2 x G83 and G80 x PS6 were earlier, hence, required less number of days to first boll and recorded the highest earliness index.Significant additive and non-additive variation exhibited in the traits expression.The variances due to general combining ability (GCA) were large in magnitude than those due to specific combining ability (SCA), only for first fruiting node, days to first flower (LP), and days to first boll (LP); the remained traits showed greater variances of SCA.These results were supported by the ratios obtained for the relative importance of additive to non-additive variances.The average degrees of dominance over all loci indicated partial dominance of various degrees for all studied traits.The broad sense heritability was greater than narrow sense for all traits.This was associated with high narrow sense heretabilities with some traits.The study concluded to the following recommendations: 1) the lines EC1, EC2, PS6 and their descendents can be utilized as a breeding nucleus to develop barbadense genotypes that can be planted up to early May, 2) LP tolerant genotypes should have low "s" index, shorter than current genotypes, having low node of first sympodial, early for days to first boll and have high yielding capacity reflected in high earliness index, 3) breeding by backcrossing with the selected genotypes followed by repeated selfing is a successful breeding strategy for improving tolerance to late planting and enhance shortening the growing season.
Author: A. Abdalla
Institution: Cairo University
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W4210639329