Physiological And Ecological Mechanisms Of Colored Cotton And White Cotton Yield And Fiber Quality Differences And Their Response To Phosphorus

Colored cotton is a natural fiber with color ecological cotton, which did not need stain and other sectors in the process, and was in line with the environmental requirements of modern society. Phosphorus was the large amount essential nutrients of plant, which was the important component of the plant. To research the mechanism of colored cotton and white cotton yield and quality differences and their phosphorus utilization can promote colored cotton yield and quality cultivation, which was of great significance. For the lower colored cotton yield and quality of the status quo, four different fiber colors of cotton varieties as materials, colored cotton and white cotton yield and quality differences, their growth and developmental characteristics under different phosphorus levels, physiological and biochemical metabolism mechanisms, photosynthetic capacity differences, dry matter accumulation and nutrient distribution had been explored and analyzed. The results were as follows:1. A laboratory experiment was carried out to study the root morphology, root/shoot ratio and leaf physiological activity of three colored cottons(CCRI 51 light brown cotton, CCRI 81 dard brow cotton, CCRI 82 dark green cotton) and one white cotton under different levels of phosphorus. The results showed that lower level phosphorus treatments had significantly increased root length and root surface area, while no phosphorus treatments had seriously inhibited the growth of cotton root. Lower phosphorus significantly increased total cotton root length and root surface area. Cotton total root length, root surface area, root volume and root/shoot ratio of white cotton had the most increase in 10 days after treatment. But that of light brown cotton had the most increase in 20 days after treatment. Compared to 10 days after treatment, no phosphorus increased the root growth inhibition of white and dark brown cotton in 20 days after treatment, while other species, along with the stress time, the degree of inhibition reduced. Chlorophyll(a + b) content, chlorophyll a / b value, POD, SOD activity, light saturation point and maximum net photosynthetic rate in function leaf of white cotton decreased with phosphorus levels decreasing in 20 days after treatment. Chlorophyll a/b value, proline content, SOD activity and light saturation point in function leaf of light brown cotton were significantly improved under low phosphorus stress. Chlorophyll a/b value, proline content and MDA content in function leaf of dark brown and dark green cotton significantly increased under low phosphorus stress, meanwhile, light saturation point in function leaf of dark brown cotton had also been significantly improved. Chlorophyll(a+b) content, chlorophyll a/b value, POD, SOD activity and the maximum net photosynthetic rate in the function leaf of each varieties were significantly reduced under no phosphorus condition, and the proline content had also been significantly increased. In 20 days after phosphorus treatment, cotton total root length, root/shoot ratio showed no significant correlation with physiological indicators of aboveground. Root surface area was significantly positively correlated with chlorophyll a/b value. Root volume was significantly positively correlated with chlorophyll(a+b) content, soluble sugar content and light saturation point in the function leaf of cotton, but it was significantly negatively correlated with the maximum net photosynthetic rate. Chlorophyll(a+b) content was significantly positively correlated with soluble sugar content, light saturation point and the maximum net photosynthetic rate. It showed that white cotton had the strongest resistibility to adapt short-term phosphorus stress, but it did not had a long time resistibility to phosphorus stress. Light brown cotton and dark green cotton had a a long time resistibility to phosphorus stress. And light brown cotton had the strongest resistibility, which was the phosphorus efficient variety. Dark brown cotton had the centered resistibility to phosphorus stress.2. In field condition, cotton yield, fiber quality, morphological physiological biochemical characteristics, dry matter accumulation and distribution of different cotton genotypes in phosphorus and non-phosphorus conditions were studied. The results showed that: boll number and boll weight of light brown cotton had the highest seed cotton yield. While the boll number of white cotton was not significant with dark brown and dark green cotton, but the higher boll weight of white cotton made its seed cotton yield was higher. This is the direct cause of seed cotton yield differences of different cotton genotypes. Yield components were significantly associated with dropout rate and dry matter accumulation. Dark green cotton dropout rate was significantly higher than other varieties. Light brown cotton had the lowest dropout rate. White cotton had little difference with dark brown cotton Dry matter accumulation and the reproductive organ distribution rate of white cotton was significantly higher than dark colored cotton. Dry matter accumulation and the reproductive organ distribution rate of light brown cotton had little difference with white cotton. Dry matter accumulation and excessive vegetative growth of dark colored cotton made the yield organ distribution rate was too low. The study also showed that, function leaf physiological activity was significantly associated with boll weight, reproductive organs distribution rate and dropout rate. Differences of POD, SOD activity and soluble protein content in function leaf of all varieties were as follows: light brown cotton>white cotton>dard brown cotton>dard green cotton. Dark green cotton had the hightest MDA cotton in function leaf. In the late cotton boll forming period, the difference of protective enzyme activities of different genotypes function leaf could lead yield and dry matter accumulation change. Since chlorophyll content and protective enzyme activities of light brown cotton were the highest in all varieties in that period, which meaned its leaves had higher physiological activities. And because protective enzyme system activity in function leaves of dark-colored cotton varieties were poor, the leaves cell membrane structure were affected, which was not conducive to the accumulation of photosynthetic products. Meanwhile, GA3, ZR and IAA content in function leaves were significantly correlated with the cotton boll weight and dropout rates. ZR and IAA content of light brown cotton were the highest. That of white cotton were followed by light brown cotton, and that of dark green cotton were the lowest. Nitrogen, phosphorus and potassium accumulation of different varieties exhibited similar laws with endogenous hormone. It showed that different endogenous hormone content of different varieties could lead different dry matter accumulation intensities, thereby affected the accumulation of nutrients.In the upper half of the average length of cotton fiber, strength and uniformity, light brown cotton was the best, white cotton followed, and dark green was the worst. Micronaire value of dark green cotton was A grade., and that of white cotton was only C grade. The boll ratio of three stage of light brown cotton was reasonable.