Single Trait Selection and Independent Culling Levels in Improving Egyptian Cotton Yield (G. barbadense L.) under Normal Irrigation and Water Deficit

Document Type : Original Article

Authors

1 Department of Agronomy, Faculty of Agriculture, Assiut University, Assiut, Egypt

2 Cotton Research Institute, Agricultural Research Center, Giza, Egypt

Abstract

TRADITIONAL breeding is an important way to develop drought-tolerant varieties. There is a dire need to develop cotton cultivars that can produce acceptable yields in water limited. This work aimed to compare single trait selection and independent culling levels for six traits in improving the seed cotton yield (SCY/p) under water deficit and normal irrigation. The genetic material was the F2-population of the cross Giza 90 ˟ Giza 95 (long staple). In the F2, the phenotypic (PCV%) and genotypic (GCV%) coefficients of variability were mostly higher under normal irrigation than under drought stress. The correlations among traits indicated that SCY/p depended mainly upon number of bolls, boll weight and seed index, and moderately on lint index, and the early plants had high yields. The GCV and PCV were greatly depleted by selection and were higher in most cases under drought stress than under normal irrigation. Independent culling levels preserved genetic variability more than single trait selection. Narrow sense heritability was mostly high under normal irrigation. The selections of both methods were evaluated in the F4 under both environments. Selection for SCY/p under normal irrigation increased SCY/p by 16.9% under normal irrigation and 8.90% under stress, while selection under stress increased SCY/p by 12.05 and 10.69% of the mid-parent under the respective environments. Single trait selection proved that selection under optimum environment performed well under optimum, and selection under drought stress was better under stress. Otherwise, ICL method of selection did well under drought stress.

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