Distribution of 14C-assimilates in boll-leaf system at full-blooming stage of three cotton genotypes with different boll weight

By measuring axial and sympodial leaf areas in the middle position and leaf area index(LAI),the distribution of 14CO2assimilates on different boll-leaf system levels in three boll-weight cotton(Gossypium hirsutum L.) genotypes were studied by feeding 14CO2 on middle axial leaf at full-blooming stage in 2005.These three different boll-weight cotton genotypes were big-boll-weight genotype(Sumian9108,7.49 g/boll),middle-boll-weight genotype(Xinmian33B,4.62 g/boll) and small-boll-weight genotype(Ceheng,3.98 g/boll).The results indicated that areas of axial and sympodial leaves in the middle position were positively correlated with boll weight.The LAI of small-boll-weight genotype was the biggest among the three cotton genotypes at full-blooming stage,followed by big-boll-weight genotype and middle-boll-weight genotype.The 14C-assimilates were mostly distributed in buds and bolls at boll-leaf system,only a little was distributed in other leaves.The proportion of 14C-assimilates in buds and bolls of big-boll-weight cotton genotype were the biggest among these three cotton genotypes,so big-boll-weight cotton genotype had stronger sink activity than other two cotton genotypes.The 14C-assimilates produced in axial leaf were mostly distributed to corresponding fruit branch.In middle-boll-weight genotype,the 14C-assimilates were mostly distributed in upper fruit branch.Only a little was distributed to the lower fruit branches and main stem point.The three bollweight cotton genotypes differed in distribution tendency of 14C-assimilates in middle axial leaf to corresponding fruit.The 14C-assimilates made by middle axial leaf at full-blooming stage were mostly distributed to bolls in the first position,and big-boll-weight cotton genotype had the biggest distribution proportion,followed by middle-boll-weight genotype and small-boll-weight genotype.As to 14C-assimilates distributed to bolls in second position,the distribution proportion in small-boll-weight genotype cotton was the biggest,followed by middle-boll-weight genotype.