Study On Distribution Of The ～(14)C-photosynthate Of Cotton With Different Boll Weight Genotypes And On Characteristics Of Hormones Distributing In "Boll-Leaf System"

Three boll-weight cotton genotypes, small-boll genotype CeHengDaMianHua, middle-boll Bt-transgenic genotype XinMian33B and big-boll genotype SuMian9108, were used to study ¹4CO₂ photosynthate distribution on "Boll-Leaf system" and characteristics of hormones distributing in three different boll-weight cotton genotypes at the experimental station of Hebei Agricultural University from 2004 to 2005. By feeding ¹4CO₂ on different leaf position at different stage and using ELISA, the author scientifically studied the distribution of photosynthate made by sources in different position, the rule of sink taking use of photosynthate and the relationship between hormones and photosynthate's distribution. This research studied how to maximumly changed the outcome of source into the accumulated substance in sink (yield), which provided theoretical support on the study of bud and boll drop. The results were as follows.The amount of assimilating substance of leaves in main cotton stem and fruit branches was different in different growing periods. At squaring stage, the leaves' photosynthate assimilation amount (cpm, the followed ones are the same) in fruit branches in these three boll-weight cotton genotypes were all higher than that in main stem. At flourish flowering stage, the leaves' assimilation amount in the lower position of main stem was bigger than that in fruit branches for CeHeng and SuMian, but for 33B the leaves' assimilation amount in the lower position of fruit branches was bigger than that in main stem;to main stems, the leaves in lower position had bigger assimilation amount than leaves in middle position for three boll-weight cotton genotypes. At boll-opening stage, the upper leaves on main stem showed greater assimilation amount than fruit branch leaves for 33B and SuMian, and the main stem leaves' assimilation amount of 33B was the largest in three genotypes.Most of the ¹4C-photosynthate made in lower main stem leaves stayed in labeled leaves for three cotton genotypes and CeHeng had the least amount of stayed photosynthate of all. As to the photosynthate translocated outside, only a few of them exported to young bud, most of them exported to other organs. Also, most of the ¹4C-photosynthate made by leaves in lower position of fruit branches stayed in labeled leaves for three cotton genotypes, but CeHengDaMianHua had the largest amount of stayed photosynthate of all. For three boll-weight cotton genotypes-CeHeng, 33B, SuMian, the respectively proportion of photosynthate translocated to young bud is 23.08%, 28.14%, 28.54%, while the proportion of photosynthate translocated to vegetative organs like other leaves, main stem and root was very small.At flourish flowering stage, the photosynthate of three boll-weight cotton genotypes was mainly exported to its corresponding fruit branch. When feeding main stem leaves in middle and lower position, the proportion of photosynthate distributed to buds and bolls on corresponding fruit branch for big-boll genotype was the largest among three cotton genotypes, while the proportions of photosynthate distributed to the next buds and bolls on corresponding fruit branch were all small. When feeding fruit branch leaves in lower position, the proportion of photosynthate distributed to buds and bolls on corresponding fruit branch for small-boll genotype was the largest among three cotton genotypes, and the proportions of photosynthate distributed to bolls in the next position on corresponding fruit branch for middle-boll genotype was the largest. When feeding fruit branch leaves in middle position, the proportion of photosynthate distributed to buds and bolls on corresponding fruit branch for middle-boll genotype was the largest among three cotton genotypes, and the proportions of photosynthate distributed to the next bolls on corresponding fruit branch for big-boll genotype was the largest of all.At boll-opening stage, small-boll cotton genotype had small proportion of photosynthate translocted outside and those photosynthate mainly exported to vegetative organs. Middle-boll and big-boll cotton genotype had large proportion of exported photosynthate, mainly providing corresponding fruit branch. The photosynthate made by leaves on the second position in middle fruit branch, mainly provided corresponding bolls first, then translocted to bolls on the next position. For middle-boll cotton genoytpe, the photosynthate dispersedly distributed to corresponding fruit branch.The IAA contents in bolls and leaves on the first position of lower and upper fruit branch for different boll-weight genotypes reached lowest at 35d, while bolls and leaves on the first position of middle fruit branch reached summit. The IAA contents in cottonseeds in all position for different boll-weight cotton genotypes all had summit at 15d and the peak value of big-boll cotton genotype is biggest, except middle-boll genotype's IAA contents in cottonseeds on the first position of middle fruit branch and on the third position of lower fruit branch was small and showed little changes in the whole growth period.The ABA contents every position of upper fruit branch is bigger than middle and lower fruit branch for different boll-weight genotypes The ABA content in cottonseeds of upper fruit branch had a summit at 15d for different boll-weight cotton genotypes. And the contents of GA and IAA had the same tendency.