Application of gibberellic acid and ovule-embryo culture in interspecific hybridization of diploid and tetraploid cotton species

In order to transfer resistant gene from related wild species of cotton (2n=2x=26) to commercial species (2n=4x=52)، and to establish an efficient genetic broadening system، gibberellic acid and ovule-embryo culture were used. Crosses between two Gossypium hirsutum commercial cultivars (Sahel and Sephid) as a seed parents with pollen grain of Hashem Abad and Kashmer diploid cultivar (G. arboretum) have been carried out into direction. For getting mature boll، pollinated flowers have been treated with 0 and100 ppm concentration of GA3 to overcome early abscission of pollinated flowers. There was a significant difference between GA3 concentrations and crosses for boll development at 5% probability level، using Chi-square test. Highly significant differences have been observed between control and hormone growth regulator for hybrid boll setting. Maximum boll development (64%) was observed in Sephid ×Hashem Abad when treated with 100 ppm GA3 after 45 DAP (Day after pollination). Only 7. 5% of pollinated flowers led to develop boll in absent of GA3. Highly significant differences have been observed between 3 and 45 days old ovule-embryo culture on MS medium at 1% probability level. Direct embryo germination was observed from 45 days old embryo culture in MS hormone free medium. No significant differences were observed between tetraploid and diploid as seed parents for embryo germination. There was no direct plantlet regeneration in culture of isolated ovule less than 45 days. The seeds were not developed as well as those harvested from the self pollinated female parents. The sterile triploid hybrid plants showed more vigorous than either parent.