Improvement of two locally adapted cotton cultivars in earliness by induced mutations

Abstract

Seeds from two locally adapted cotton cultivars, Eva and Zeta-2, were irradiated by 300 Gy γ-irradiation in order to create useful variability for earliness within each cultivar, and then to select for desirable recombinations. Selection for earliness was applied in the M₂ generation and the earliest 2% of the mutants were selfed for further evaluation. After eliminating the undesirable phenotypes, the remaining material was sown in progeny rows as the M₃ generation. Selection for earliness based upon morphological and physiological characteristics resulted in 5 early mutants from cv. Eva and 3 early mutants from cv. Zeta-2. These lines were further evaluated the following year for earliness, yield, fibre, and seed quality in 3 locations across the Greek cotton belt, using a randomised complete block experimental design with 4 replications. Among the 5 early mutants of cv. Eva, only one was consistently early at all 3 locations, whereas the other 4 mutants showed significant differences in the first growth stages. From the 3 early mutants of cv. Zeta-2, one was consistently early at all 3 locations. Plant height, lint yield, length, micronaire, strength, etc., as well as oil %, protein %, and gossypol %, were not significantly different from the untreated checks.