Cyto-morphological evaluation of back-crossed genotypes derived from Iranian endemic cotton cultivars Garmsar and Qum Red-boll with arboreum species

This study was carried out in order to investigate the chromosomal behavior duringmeiosis, morphological assessments and fibers quantitative and quality traits in herbaceum (Iranian endemic), arboreum, F1 hybrids of two species and Bc4 genotypes. Since the arboreum species used in this study had good fiber quality, so in order to improve the fiber quality of endemic cotton, hybridization between twospecies which followed by several back crossing with endemic cultivars was performed in Cotton Research Department of Varamin, Iran. The endemic cultivars were Garmsar and Qum red-boll (herbaceum) and VTDL (arboreum). Regarding morphological characters, the F1s traits were intermediate and Bc4 showed intermediated and more resembled to endemic parents traits. Cytological investigation showed that in F1s the adjacent and alternative quadrivalents were frequently occurred. In population of Bc4 offspring the quadrivalents were appeared in low frequency. Besides, other abnormalities like univalent, trivalents and triple sets of chromosomes in MII and AII were found which resulted in deviation from Tetrads. The fiber quantitative and quality traits investigation results showed that the hybrid Garmsar x arboreum had fibers with 26.7 millimeter length which caused by transferring the genes from arboreum parents to endemic cotton cultivar.