| This experiment mainly studied:(l)heterosis of upland cotton varieties of different ripening stage (early, medium, late) and their genetic effects;(2)heterosis of hybrids between above types of upland cotton varieties with island cotton and their genetic effects;(3)photosinsesis rate of above hybrids.The results showned that early typexmedium type,medium type x medium type of upland cotton have stronger hetorosis in ripening stage,yield and fibre quality In earlyxearly combination of upland cotton, more transgressive early hybrids were seen, yet their yield and quality were inferior to other types of combination;though transgressive early hybrids were also obtained among earlyxlate, mediumxlate and latexlate combination, their growth period is generally longer than earIlyxmedium, mediumxmedium, and their yield, quality were below the mediumxmediusn and earlyxmedium hybrids. Compared with hybrids between upland cotton varieties, hybrids of upland cotton with island cotton had lower photosynsesis rate and yield, but higher quality. Among combinations of early, medium and late upland varieties with island cotton, hybrids of earlier ripening stage, higher yield and better quality can be obtained from medium upland cottonxisland cotton. Therefore making upland cotton crosses of earlyxmedium, medium xmedium and medium upland cottonx island cotton combination can get transgressive types in ripening stage, improve yield and quality at a time, breed hybrid or conventional varieties of early ripening, higher yield and better quality. |
