Physiological And Biochemical Study On The Response Of Amur Grape (Vitis Amurensis Rupr.) To Drought Stress

A sheltering cultivation and natural drought experiment was conducted to analyze the changes of osm-regulating substances, antioxidase, endohormones, photosynthesis and ultrastructure in the response to drought stress, by using annual stock shoot of 4 kinds of amur grape cultivars including"Shuangfeng","Shuangyou","ZuoshanⅠ"and"ZuoshanⅡ"as test materials, a grape rootstock variety"Beida"as the control materials. The results were as follows:1. The content of proline(Pro)increased and the content of soluble sugar decreased with the increasing drought stress in amur grape, while the soluble protein content increased first and then decreased. The content of Pro changed more intensitively and the content of soluble sugar decreased less seriously than other varieties in"ZuoshanΙ". The soluble protein decreased in"ZuoshanΙ"under seriously drought, but decreased not significantly. The content of proline and soluble protein sustained a high level in"Beida", without changing seriously. The soluble sugar decreased evidently under different treatments in"Beida", but it is higher than amur grape. This stated"ZuoshanΙ"have a great faculty of osmotic-regulation among 4 kinds of amur grape, and the osmotic-regulating faculty of"Beida"is greater than amur grape.2. MDA content accreted gradually for broken down by reactive oxygens explosion in"Beida"and amur grape under drought stress, variation amplitude of"Beida"and"ZuoshanΙ"was less than other varieties. Superoxide dismutase (SOD) and digestible nitrogen (POD) increased firstly and then declined with the increasing drought in amur grape. The two enzymes played a synthetic role in avoiding damage of reactive oxygen species, while the ability of scavenging oxidative radicals decreased when the soil water content less than a certain level.The change of SOD and POD activity in"Beida"is less than amur grape, but the SOD activity is in a high level and the POD activity is in a constantly increasing tendency. This result indicated resistense ability to drought stress was not only relate to the trend of change, but also to the activity of enzyme.3. The content of abscisic acid and zeatin riboside increased in varying degree, and indole.3-acetic acid and gibberellic declined under drought stress, but there were not a connection between cumulant and variety.4. Photosynthesis capacity decreased under drought stress in amur grape. Transpiration rate and stomatal conductance changed in the same trend with net photosynthetic rate, but intercellular gas concentration level increased firstly and then decreased. PSⅡperformance index (PIABS) and maximal photochemical efficiency decreased, PIABS was more sensitive to drought stress, so we can use it as a drought resistance index. Analysis of JIP-test showed that the J and I steps at fluorescence transient were increased under drought stress, the appearance of the K peak was also observed in"Shuangfeng". The result showed that donor side, acceptor side and oxygen evolving complex damaged under drought stress. At the same time, amur grape started-up ego defense mechanisms, heat dissipation increased."Shuangfeng"suffered more than"ZuoshanΙ"and"Beida".5. The organelles in amur grape leaves were damaged in varying degree under drought stress. The chloroplast membrane dissolved and fragmented, thylakoid lamellas disarranged and vacuolated, starch grain became less, plastoglobulis became more and larger, and plasmolysis occurred. Effect on mitochondrion was later than chloroplast, but severe drought contributed to the appearance of more mitochondrion and less cristae, mitochondrial membrane became unclear. Nucleus inclined to applanation, nucleus membrane dissolved partly, substance in nucleus outflowed. Endoplasmic reticulum became shorter, endoplasmic reticulum tune became intumescentia,ribosome adherentted to endoplasmic reticulum dropped.