Abstract:In this study, hybrids of the interspecific cross between Gossypium barbadense L. and Gossypium hirsutum L. are employed as materials. The introgression line-to-line plants were crossed to break the undesirable linkage for breeding this semi-okra cotton germplasm which is called the ZKY-1. To provide theoretical data for further deploying the new germplasm ZKY-1 in breeding program, the agronomical character, fiber properties, physiological, biochemical and genetic characteristics of the semi-okra germplasm were evaluated. The result showed that the yield of ZKY-1 is slightly lower than the wide-cultivated control upland cotton varieties CCRI49. ZKY-1 showed the improved fiber properties, with the fiber length of 34.5 mm and the breaking tenacity of 38.4 cN·tex-1. The hereditary capacity for fiber quality of ZKY-1 was high, while the derived hybrids with various upland cotton varieties show a relatively strong mid-parent heterosis, for instance, on the fiber length and fiber breaking tenacity, except that few combinations showed significant transgressive heterosis. The leaf lobe index of ZKY-1 was 0.75±0.01, indicating a semi-okra leaf type. The leaf type of the F1 hybrid between ZKY-1 and normal leaf-type G.hirsutum L. is intermediate form and its F2 offspring showed the segregation on this character. The Chi-Square test indicated that the semi-okra trait was controlled by a dominant gene. Besides, the plant height, first fruit node, numbers of fruiting branches, germination rate and germination potential are all higher than the parent CCRI49. No significant difference in the net photosynthetic rate between the ZKY-1 and the CCRI49 at the square stage and boll stage was observed, although the ZKY-1 was significantly lower than the CCRI49 at the flowering stage. For the total content of chlorophyll, no significant difference between ZKY-1 and CCRI49 was detected at the square and flowering stage. But at the boll stage, the total content of chlorophyll in ZKY-1 was significantly higher than the CCRI49. In addition, ZKY-1 showed significantly higher SOD and POD activities relative to CCRI49 at the square stage and the flowering stage. No significant difference was found in the content of MDA. At the boll stage, ZKY-1 exhibited the lower POD activity, but significantly higher MDA content if compared to CCRI49. Taken together, ZKY-1 exhibited stable inheritance on semi-okra and excellent fiber quality, which can serve as an excellent germplasm resource for improving fiber properties and breeding high photosynthetic efficiency varieties.