Effects And Mechanism Of Source-sink Regulation On Boll And Fiber Quality In High-quality Cotton

The cultivar of high-quality cotton, Kemian No.7, which was planted widely in the southern cotton production area of China, were used to study the developmental characteristics and regulation of boll and fiber quality with the conventional fiber quality cultivar Sumian No.9 as the control. The objection of this study was to investigate the effects and mechanism of source-sink regulation on boll and fiber quality in high quality cotton cultivar. The main results are as follows:1. The source-sink regulation caused changes of the boll volume similar between high-quality cotton and conventional cotton. With the leaves cutting, the boll volume decrease, and with the squares cutting, the boll volume increase. The boll volume and seed index of the high quality cotton decreased less than the conventional and the boll weight dropped to a greater extent than the conventional with the leaf-cutting. By square removal, the boll volume and seed index increased less than the conventional, the boll weight was the same as that of the conventional and the increase of boll weight was during 20 days after anthesis (DAA).Compared with the conventional cotton, the effect of source-sink regulation on the high quality cotton was smaller. In the treatment of cutting 3/4 leafes, the boll volume decreased by 14.8% at 40 DAA for Kemian No.1, by 17.9% for Sumian No.15. In the treatment of cutting 1/2 square, the boll volume increased by 19.2% and 36.2% for Kemian No.1 and Sumian No.15 respectively. The effect of cutting square treatment on boll weight for two cultivars was similar. But in comparison with the conventional cultivar, the effect of cutting leaves treatment on the boll weight was more significant for high-quality cotton. Compared with the control, in the cutting 1/2 and 3/4 leaves area treatment, the boll weight of decreased by 27.7% and 13.35% for Kemian No.1, by 10.37% and 0.64% for Sumian No.9 respectively at boll open stage. From 20 DAA, the effect of cutting leaves area on the boll weight, especially the cutting 3/4 leaves area, became bigger. However, with the cutting square treatment, the boll weight increased more before 20 DAA. The speed of boll weight decreasing in the cutting leaves treatment became faster for Sumian No. 9 at 40 DAA. The effect of the cutting square for Sumian No.9 was similar with the Kemian No.1. The source-sink regulation treatment had lower effect on seed index for the high quality cotton, but the stage was different. The treatment effect the seed index before 30 DAA, especially at 20 DAA for the high-quality cotton, after 30 DAA for the conventional cotton.2. The source-sink regulation caused changes of the fiber quality similar between high-quality cotton and conventional cotton. With the leaves cutting, the fiber quality decrease, and with the squares cutting, the fiber quality increase. By leaf-cutting, the decrease of the high-quality cotton's fiber length was below the conventional. Compared with the conventional the decrease of the high-quality cotton's fiber strength was not significant, the fiber maturity less than conventional cotton, fiber micronaire showed different characteristics, fiber micronaire for high-quality cotton dropped significantly. Clipping square had little effect on the quality of conventional cotton just the opposite, the fiber length of the high-quality cotton was greater than the growth rate of the conventional, fiber strength increased less than the conventional, maturity increase rate was slower, the enhance of fiber micronaire was greater.3. The changes of source-sink regulation caused changes of transportation and allocation of photosynthetic products under different leave source regulation. The soluble sugar content, sucroase content, the exportation rate of the leaf 14C photosynthetic products, the sap of soluble sugar and nitrogen in boll staple phloem, soluble sugar content, and sucroase content in the boll shell decreased less than that of cultivar Sumian No.9 under more strong lave source. The soluble sugar content, sucroase content, the exportation tate of the leaf 14C photosynthetic products, the sap of soluble sugar and nitrogen in boll staple phloem, soluble sugar content, and sucroase content in boll shell, seed and lint enhanced greater than that of cultivar Sumian No.9 under more strong leave source, which sere typical during the boll filling period.4. The changes of source-sink regulation caused changes of the physiology activity of the fiber lengthening and thickening. With the leaves source decrease, the fiber ABA content and the cellulose content of cultivar Kemian No.7 reduced less than that of cultivar Sumian No.9, especially at 40 DAA, but the UDPG-Pyrophosphorylase (UDPP) Activities were at same reduction between Kemian No.7 and Sumian No.9, the fiber Sucroase Synthase (SS) activities of cultivar Kemian No.7 reduced greater than that of cultivar Sumian No.9. With the squares became less, the fiber IAA content, ZR content and the ATPase activity in the fiber extension period of cultivar Kemian No.7 increased higher than that of cultivar Sumian No.9.The fiber ABA content, cellulose content, the UDPGase activities and the sucroase activities in the fiber deposition period of cultivar Kemian No.7 enhanced greater than that of cultivar Sumian No.9.