| Five cottons varieties, small-boll varieties SanJiangBaDaHua and CeHengDaMianHua, middle-boll Bt-transgenic variety XinMian33B, big-boll Bt-transgenic hybrid CCRI29 and extreme big-boll cotton SuMian9108, were used to study the coordination of source-sink at the experimental station of Hebei Agricultural University from 2002 to 2003. The author scientifically studied on the physiological characteristics of source-sink and on others index related closely to yield and fiber quality in different boll-weight genotype cottons in order to elucidate the characteristics of source-sink in different genotypes, by which to provide theoretical support on drawing up cotton management strategies and identifying useful physiological index in early period of breeding work. The results were as follows:1. Cotyledon area was an index of yield in early growth period of cotton and existed positive correlation to seed cotton weight per boll. Dry weight of small-boll variety cotton plant was lower than big-boll variety in early period, and it was higher than big-boll variety after three leaves stage. As to Bt-transgenic, the cotyledon area and plant's dry matter accumulation during seedling period were less than other cotton varieties. It suggested that vegetative growth of Bt-transgenic cotton was slower than that of others.2. The boll-weights significantly positively correlated with the content of chlorophyll, soluble sugar and amylum content in the leaves, the content of soluble sugar and amylum in the boll-bell during the first 25d after flowering, the average increase in dry matter weight of boll per day during the induction of weight enhancement of ball period and cotton fiber's quality indexes, such as, length, strength and uniformity; while negatively correlated with the content of amylum in cottonseed at the first 35d after flowering, SOD activity during boll-opening stage in main stem leaves and the ratio of boll-bell's weight to boll.3. The chlorophyll a/b in branches' leaves of every cotton varieties decreased with the lowing of branches' positioning, which showed that the lower branches' leaves tolerant sunshine deficiency. The content of usable sugar (toll content of soluble sugar and amylum) was higher during vegetative growth period than in reproduction growth period, with having the maximum value at the first budappeared. The ratio of usable sugar to soluble protein content reached the summit at flourish flowering stage. The content of soluble sugar in cottonseed was affected by boll's spatial position. The SOD activity declines and the POD activity increased at the same time in main stem leaves, which suggested that the leaves would pre-mature senescence.4. The source-sink physiological characteristics of small-boll variety showed that the change of LAI was beneficial to form high-yield group canopy structure. But its many physiological parameters, such as, lower chlorophyll content and chlorophyll a/b and weaker photosynthesis capability all indicate that small-boll couldn't use strong light to produce photosynthetic products as much as big-boll categories produced, showing that the source quality of small-boll was poor. Under the effect of source limitation, small-boll variety had shorter induction period of weight enhancement of boll; the capability of utilizing photosynthesis matter of cottonseed of small-boll genotype, which just contested that the sink activity of small-boll category was weaker than that of big-boll ones. Moreover, the boll weights of small-boll category fluctuated between a large of scope. The heaviest boll was in the upper branches, while in the same branch, the boll weight of the third position was heavier than that of first position.5. As for the big-boll genotypes, the heaviest bolls located on the upper branches, at the same time, in a branch, the boll weight of first position was heavier than that of third position. Big-boll categories had longer period of keeping high chlorophyll content in leaves, stronger photosynthesis and more plentiful...
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