棉 花 学 报 Cotton Science 2007，19(3)：189-193
Relationship between Yield Formation and Source-Sink of Cotton Cultivars with Different Boll Weight Abstract：Five cotton cultivars with different boll weight were used to study on the source-sink coordination of different cultivars. The experiment was conducted on Hebei Agricultural University farm in 2002 and 2003 under density of 52，500 plants · hm-2. The author analyzed the number of bolls in unit area leaf，the number of total boll per plant，the ratio of boll and bud dropping and the content of hormone in boll seed at different growth stages. Furthermore，we also study on the change of leaf area index (LAI)，chlorophyll content and net photosynthesis production during whole growth period of cotton. The result showed that lower IAA/ABA was found in seed of small-boll cultivars，which might illuminated that this kind of boll was the weaker in competition with vegetative tissue， and the boll was easier to drop compared with that of bigger-boll cultivars. For feedback on the weaker sink of small-boll cultivars，the content of chlorophyll in the leaves and the net photosynthesis production were lower although the LAI of small-boll cultivar was larger than that of big-boll cultivar during whole growth stage. Contrary to small-boll cultivar，Big-boll cultivar Sumian 9108 has a strongest sink among all cultivars in the experiment，which induced no photosynthesis production enough to vegetative growth although stimulated a higher level of chlorophyll and more effective photosynthesis production capability. The relative lower LAI of big-boll cultivar compared to the sink caused a great dropping of boll that appeared on August 15th ago. As for the cultivars with middle weight of boll，the capability of sink absorbing photosynthetic product was stronger than that of others cultivars with high level of IAA/ABA. The chlorophyll content and effective photosynthesis production were more higher in the late period of cotton growth compared with others cultivars，which could provide more photosynthetic product to boll develop. This might beneficial to boll dropping decrease and yield increase. It can be concluded that neither too small-boll nor too big-boll cultivars were beneficial to high ratio of boll setting. The major factor inhibited small-boll cultivars' yield was weaker capability sink with overgrowth vegetative. As for big-boll cultivars ，it was the relative weaker source paralleled with senescence.
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