Study On Leaf Senescence Physiology And Anti-aging Technology Of Grape Cultured In Protected And Delayed Cultivation

To investigate the effects of various treatments on leaf senescence,the two contrasting grape cultivars V. vinifera cv.Italia(slower speed of leaf senescence) and V.vinifera cv. Centenial seedless(faster speed of leaf senescence) cultured in protected and delayed cultivation were used as materials. Treatments with three replicates were investigated consisting of red light,blue light and spraying with 6-BA, amino acid selenium,gibberellin,brassinolide and secondary shoots.The aim of this study is to provide a theoretical basis for preventing leaves from early aging. The main results were as follows:1. Different treatments on the leaf morphology traits:(1) The deciduous period of Italia in the red light treatment was about two month later than the control,the deciduous period of Centenial seedless was about a month and a half later than the control; Leaves in the blue light treatment were severely damaged at the early stage, while the speed of leaf senescence slowed down at the later, the deciduous period of both cultivars was about one month later than the control.(2) Under the treatment of 6-BA and amino acid selenium, the deciduous period of Italia and Centenial seedless was about half a month later than the control.(3) Under the treatment of gibberellin, the deciduous period of both varieties was about 5 days later than the control,while the deciduous period of Italia and Centenial seedless in the brassinolide treatment was similar to contrast,and brassinolide did not have the effect of anti-aging.2. Different treatments on leaf quality and photosynthetic characteristics during leaf senescence:(1) As compared to control,red light significantly increased the chlorophyll and soluble protein contens,the net photosynthetic rate, and the ratio of Fv/Fm, red light also had better effect on the chloroplast structure and grana lamellae was clear; While blue light significantly decreased the chlorophyll content,the net photosynthetic rate, the ratio of Fv/Fm and destroyed the chloroplast ultrastructure at early stages of leaf senescence, at later stages the values of physiological indexes were gradually higher than the control and the damage to chloroplasts at later stages of senescence process became less severe. The soluble protein always maintained high level in the blue light.(2) As compared to control,6-BA and amino acid selenium applications obviously increased the chlorophyll and soluble protein contens,the net photosynthetic rate,the ratio of Fv/Fm,and maintained the structure of grana lamellae and chloroplast membrane.(3) As compared to control,exogenous gibberellin significantly increased the chlorophyll and soluble protein contens,the net photosynthetic rate,the ratio of Fv/Fm and alleviated the damage to ultrastructure of chloroplast.Meanwhile,treatments with brassinolide significantly increased the chlorophyll and soluble protein contens,the net photosynthetic rate, the ratio of Fv/Fm and maintained the integrity of chloroplast structure at the early stage of leaf senescence, while had no significant effects on leaf senescence in the late.3.Different treatments on active oxygen content and antioxidant enzyme activity:(1)Under the condition of red light, the activity of SOD, CAT were increased significantly,the content of MDA、O2?、H2O2 were decreased significantly and leaf senscence process was delayed when compared to the control. In treatments of blue light, the activity of SOD, CAT were significantly lower than that in the control at the early stage of leaf senscence,after that the activitiy of SOD, CAT in the blue light treatment were gradually higher than the control,the content of MDA、O2?、H2O2 were significantly higher than that in the control from beginning to end.(2)As compared to control,exogenous amino acid selenium and 6-BA delayed the decrease of SOD, CAT activities, decreased the content of MDA、O2?、H2O2 and postponed the senescence of functional leaves.(3)In treatments of gibberellin,the activity of SOD,CAT were increased significantly, the content of MDA、O2?、H2O2 were decreased obviously as compared to the control, the leaf senescence process was delayed; Although the activity of SOD, CAT were increased and the contents of MDA 、 O2?、H2O2 were decreased by brassinolide during the early phase of senescence, no significant differences between brassinolide treatment and the control were found at the later phase of senescence.4. Different treatments on content of endogenous hormones:(1)In both cultivars, as compared to the control,red light significantly decreased the GA3 content, but increased the ZR content and decreased the ABA content.Blue light had little effect on GA3 content,but increased the ZR and ABA content. Comparison of different light qualities on the ratio of endogenous hormones we found that red light significantly incereasd the ratio of(GA3+ZR)/ABA and postponed the senescence of functional leaves;While blue light significantly decreased the ratio of(GA3+ZR)/ABA at the early stages of leaf senescence,accelerating the senescence process,after that the ratio of(GA3+ZR)/ABA in the blue light treatment were gradually higher than the control and blue light could delay leaf senescence to a certain extent at late sampling stage.(2)Treatments with amino acid selenium,6-BA and gibberellin significantly increased the endogenous ZR and GA3 contents and the ratio of ZR/ABA,GA3/ABA and(ZR+GA3)/ABA,while the content of ABA was decreased significantly at the same stage. As compared to the control,the contents of GA3, ABA in the two cultivars were increased significantly under spraying plant with brassinolide,but the content of ZR was decreased.Under the brassinolide condition, the ratio of endogenous hormone GA3/ABA was always higher than the control, but since November 23, the ratio of endogenous hormone ZR/ABA was decreased significantly, the ratio of(ZR+GA3)/ABA was showed no significant increased as compared to control. IAA as one of plant endogenous hormones showed double roles that maintained growth in the earlier period,and promoted senescence in the later period.5. Study on physiological mechanism of leaf senescence of primary shoots and winter secondary shoots: Since October 24, the contents of chlorophyll and soluble protein,the net photosynthetic rate, Fv / Fm and SOD, CAT activity in the winter secondary shoots was significantly higher than in the primary shoots, and MDA、O2?、H2O2 contents were significantly lower than in the primary shoots,and the contents of ZR and GA3 were relatively higher in the secondary shoots,while the ABA content was relatively lower.6. There were differences between Italia and Centenial seedless for the rate of leaf senescence. At the late stage of growth,Italia was still able to keep higher contents of chlorophyll and soluble protein,net photosynthetic rate, ratio of Fv/Fm, activities of SOD,CAT and lower contents of MDA、O2?、H2O2,and maintained the balance of endogenous hormones, thus effectively prolonging the leaf senescence.7.(1)The physiological mechanism of primary shoots and winter secondary shoots in delaying leaf senescence: The most obvious morphological changes were the leaf color from green to yellow, and at the cellular level leaf senescence was characterized by the disintegration of the chloroplast,the decreased chlorophyll content, the degradation of proteins, the decreased photosynthetic rate,and the peroxidation of the cell membrane. Changed levels of endogenous hormone were closely related to leaf senescence,the decreased content of CTK and increased content of ABA were the main factor to start aging of grape leaves in this paper.(2)Exogenous 6-BA, amino acid selenium,gibberellin,red light and secondary shoots can decline the damage of membrane lipid preoxidation, prolong the functional period of leaves, and delay the leaf senescence, so it can be used in the actual production of grape.