Performance of male-sterile stocks of cotton as parents and hybrids

Abstract

Two male-sterile lines of G. hirsutum containing G. anomalum or G. arboreum cytoplasm, their respective maintainer lines, and the M8 variety from which the male sterility stocks had been derived, were crossed reciprocally with each of three male fertility-restoring varieties. The F₁ hybrids of the four male sterility stocks did not differ significantly in either lint yield or boll numbers. However, significant though small differences occurred in other traits including boll weight, lint percentage, seedling growth and some fibre properties.

Pair-wise comparisons between sets of hybrids containing anomalum v. hirsutum, anomalum v. barbadense, arboreum v. hirsutum and arboreum v. barbadense cytoplasms showed that the diploid species cytoplasms did not significantly affect lint yield or the yield components of number of bolls and boll weight, while the other yield component, lint percentage, was only affected in one instance. Significant cytoplasmic differences in other attributes were rare.

The recurrent G. hirsutum parent M8 outyielded its sterile derivatives both as a cultivar and as a hybrid parent. The yield decline of the male-sterile stocks was ascribed to nuclear (genomic) changes resulting from strong selection pressure for sterility during their development. It was concluded that, while the production of cotton hybrids from these male-sterile stocks is technically feasible, their practical utility is limited.