| With Xinmian33B, a Bt-transgenic cotton variety, as a control, the growth and physiological characteristics of Bt-transgenics hybrid cotton (CCRI29) were studied in the mid of Hebei, which may offer a theory basis for establishing a favorable boll setting model and cultivation managing strategy of hybrid cotton.The result suggested that CCRI29 had expressed significant heterosis in growth of height, number and area of leaves, which overcome the weakness of the normal Bt-transgenic cotton in seedling period. The representation of CCRI29 in procreation development was the boll developed fast and prematurity well. On the allocation of the dry matter, the ratio of the reproduction organ was increasing with the delay of sowing date. The dry matter accumulation of boll suggested that CCRI29 had significant heterosis in nutrition matter repartition of boll shell and dry matter accumulation of seed cotton. Suitable early sowing was favorable for the dry matter in boll shell to be transported from shell to seed cotton, which could improve the weight per boll increasingly. In addition, the transportation of dry matter from shell to seed cotton in the middle boll were much higher than that of the upper lay and underlayer boll.On the aspect of physiological property, the net photosynthetic rate and chlorophyll percentage in function leaves of CCRI29 was higher than those of Xinmian33B. The soluble protein in function leaves of CCRI29 was much higher than that of xinmian33B before flowering, which suggest its nitrogen metabolism was faster, and the soluble sugar was much higher after flowering, which suggest its carbon metabolism was faster, so metabolism of CCRI29 was faster than that of Xinmian33B in the whole life. Starch percentage in the boll shell of CCRI29 was lower, but the starch accumulation peak value in the seed was higher. At the same time, nitrogennutrition in the boll of CCRI29 was distributed more effectively to the seed than those of xinmian33B. Suitable early sowing was favorable for increasing soluble sugar and protein in boll shell, function leaves, as well as soluble protein in the seed, however, reducing soluble sugar percentage in seed and starch accumulation in boll shell and seed. With ascending of branch node, soluble sugar in the shell was increasing. The soluble protein percentage was lowest in the boll shell and it was highest in the seed of the middle node. Those indicated that Bt-transgenic hybrid cotton (CCRI29) have definite heterosis in photosynthetic capacity, carbon and nitrogen metabolism rate, development of boll shell and seed, and matter allocation etc, which established a good basis for yield formation.In addition, compared with Xinmian33B, Bt-transgenic hybrid cotton (CCRI29) had significant superiority in yield, especially in lint yield, which was above 23.68%. On the character of yield components, boll weight and lint percentage of the CCRI29 was significantly higher than that of xinmian33B, and the number of boll per plant was no difference in the two Bt-transgenic cottons. The fiber strength of CCRI29 was significantly lower than that of Xinmian33B, but the mike value of the middle and upper boll were well than those of Xinmian33B in suitable early sowing, and other guide lines of lint quality were as well as Xinmian33B. So suitable early sowing was favorable to improving the lint quality of CCRI29. Having improved seed cotton weight per boll, the suitable early sowing is favorable to have improved greatly seed cotton and lint yield before frost injury. The lint percentage of CCRI29 differed positive significantly in different branch node and the upper boll was highest, and the middle boll was higher than lower boll. The seed cotton weight per boll in the middle was highest among the three parts, and that in the underlayer was lowest. According to the synthesis result of the research, the quality of boll in the middle was the best among the three parts, and that in the underlayer was worst. The product of seed cotton weight per boll and lint percentage in the mi...
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