Effect Of Sucrose And Different Hormones On Cotton Premature Senescence

With the material of transgenic Bt insect-resistant cotton, the experiment studied the effects of cotton growth and senescence characteristic under the treatments of SUC, BR, GA3,6-BA in the field, which was aim to seek the way of anti-aging and to provide some theoretical basis for achieving high yield and quality cotton. The results as that:1. After foliage spraying SUC(sucrose) and exogenous gibberellin-3 (GA3), brassinolide(BR) and 6-benzylaminopurine (6-BA) at different growth stages, the chlorophyll content on functional leaves of main stem was decreased only under the treatment of low concentration of BR, it was not affected obviously after full-bloom stage(July 17).2. All treatments significantly increased the soluble protein content on functional leaves of main stem except the high concentration of BR and two concentrations of SUC at early florescence (July 6). Two concentrations of GA3 and 6-BA significantly increased the soluble protein on functional leaves of main stem at full-bloom stage. At full boll stage (July 31), two concentration of GA3 significantly increased the soluble protein on functional leaves of main stem. Under low concentrations of GA3, BR, 6-BA and high concentration of GA3 obviously increased the soluble protein content on functional leaves of main stem in the later full boll stage (August 14).It showed that: high concentration of GA3 significantly delayed decreasing of soluble protein on functional leaves of main stem in flower and boll stage, and delayed prematue senescence on functional leaves of main stem.3. The treatments of low concentration of GA3 and two concentrations of 6-BA significantly increased the capalilities of absorption and utilization of main stem functional leaves for weak light at boll stage (July 31 and August 14) and improved the absorption and utilization ability of cotton for light.4. After spraying the low concentration of 6-BA significantly increased the content of soluble sugar on functional leaves of main stem at early florescence. The treaments of high concentrations of 6-BA and SUC obviously delayed decreasing of soluble sugar content on functional leaves of main stem in flower and boll stage, it was beneficial for cotton to adapt to adversity. 5. Under the treatment of high concentration of 6-BA, the activities of POD on functional leaves of main stem at full-bloom stage was higher significantly than that of (control) CK. Under the treatments of high concentration of 6-BA and low concentration of BR, the activities of SOD were higher significantly than that of CK at full-bloom stage. Two concentrations of 6-BA significantly increased the content of endogenous ZR in the later full boll stage. However the content of MDA on functional leaves of main stem with mentioned treatments all above decreased significantly so as to reduce free radical membrane damage. It is benifical for cotton to delay premature senescence.6. To deal with high concentration of GA3 significantly increased the content of endogenous ZR on functional leaves of main stem at early flowering and full flowering stage.Under high concentration of 6-BA significantly increased the content of endogenous ZR on functional leaves of main stem.But the content of endogenous ZR on functional leaves of main stem have no obvious different after full-bloom stage.To deal with high concentration of 6-BA significantly increased the content of endogenous GA3 of on functional leaves of main stem at early florescence and full-bloom stage. Low concentration of GA3 obviously increased the content of endogenous GA3, the treatment of low concentration of 6-BA significantly increased the endogenous GA3 at boll stage.The content of endogenous ABA on functional leaves of main stem only under low concentration BR treatment was higher increased obviously than that of CK at early florescence.7. At early flower stage, the treatment of high concentration of GA3 increased obviously the ratio of ZR/ABA and the treatment of high concentration of 6-BA increased obviously the ratio of GA3/ABA. At early florescence, the treatment of high concentration of 6-BA was significantly higher than CK. At full-bloom stage, the ratio of ZR/ABA with two concentrations of GA3 and 6-BA were significantly higher than that of CK. The high concentrations of GA3 and 6-BA significantly increased the ratio of GA3/ABA at early florescence and full-bloom stage. Two concentrations of GA3 and 6-BA were higher than that of CK at boll stage.8. Under treatments of low concentrations of 6-BA, BR, GA3 and GA3 with high concentration, the soluble protein contents and chlorophyll contents of middle fruit branch leaves were all very significantly higher than that of CK at initial boll-opening stage (August 31). High concentration of GA3 extremely significant increased the chlorophyll content of middle fruit branch leaves on August 19. The result was same to that of 6-BA with low concentration at boll-setting stage (September 10).9. Under high concentration of SUC, the content of soluble protein and chlorophyll of low fruit branch leaves were significantly higher than that of CK on August 13. Under low concentration of GA3, the chlorophyll content of low fruit branch leaves was very significantly higher and the soluble protein content was significantly higher than that of CK on August 24.10. The comparisons of chlorophyll a/b of middle fruit branch leaves under different treatments showed as follow, treatment under high concentration of SUC was significantly higher than that of CK on August 19. Treatments of high concentrations of GA3, SUC and 6-BA were significantly higher than that of CK on August 31.The comparisons of chlorophyll a/b of the lower fruit branch leaves under different treatments showed as follow, treatment of high concentration GA3 was very significantly higher than that of CK on August 19.Treatment of low concentration BR was significantly higher than that of CK.11. The plant height, stem diameter and plant bud numbers of whole plant under all treatments were not obviously different from that of CK. Treatments of high concentration of GA3 and high concentration of 6-BA significantly increased the leaf area index on August 17. Treatment of GA3 with high concentration significantly increased the leaf area index on August 30.12. From the result of dry matter of vegetative organs and reproductive organs with different treatments to see, treatments of SUC with low concentration and GA3 with high concentration significantly increased the total dry matter weight of vegetative organs at early boll-setting stage. Treatments under two concentrations of GA3 and low concentration of SUC significantly increased the total dry matter weight of reproductive organs at early boll-setting stage. Treatments of two concentrations of GA3 and low concentration of SUC significantly increased the total dry matter weight of whole plant at early boll-setting stage.13. From the result of cotton yield and quality with different treatments to see, treatments of two concentrations of GA3 and low concentration of SUC significantly increased the cotton yield and improved the lint percentage of the lower boll setting region. Treatment of low concentration of 6-BA significantly increased the fiber length of the upper boll setting region. The fiber strengths under the treatments of BR and GA3 with low concentrations and treatments of two concentrations of 6-BA were significantly higher than that of CK.