Effect Of Salt Stress Onplant Physiology Of Several Shrubs In Qaidam Basin

Serious soil salinization exists in Qaidam basin. For breeding of salt tolerance plant species to improve the region ecological environment, this paper selects 5 kinds of local tree species. This paper studies growth, water potential and photosynthesis characters of Tamarix chinensis, Nitraria tangutorum, Haloxylon ammodendron, Sympegma regelii and Potentilla fruticosa under different NaCl concentration gradients. Main contents of research include:comparing about growth of five plants under condition of salt stress; comparing about photosynthetic parameters and leaf water potential of five plants under salt stress at a certain time; comparing about leaf water potential of five plants in early morning over stress time; comparing about photosynthetic parameters of five plants at relatively fixed time over stress time. In order to breed salt-tolerant plants for Qaidam basin provide the basis and analyze the mechanism of salt tolerance of plants. The results were as follows:1. Under salt stress, the higher the salt concentrations are, the smaller the relative growth amounts in height and diameter of the five plants are, which is significantly different from the control. Some plants even stopped growing, for example the diameter of Potentilla fruticosa did not increase. The degree of influence on height relative growth increase:Nitraria tangutorum<Tamarix chinesis<Haloxylon ammodendron< Sympegma regelii<Potentilla fruticosa; diameter relative growth increase:Tamarix chinesis<nitraria tangutorum<Haloxylon ammodendron< Sympegma regelii<Potentilla fruticosa2. With the increase of salt concentration, the longer the stress time lasted, the lower the survival rate of plants.is. Under 800 (Y4) mmol. L-1 high concentration of salt stress, Potentilla fruticosadied 10 days later, but other plants except Tamarix chinesis died 20 days later under stress. There have been varying degrees of death, and death occurred 30 days Tamarix chinesis phenomenon stress. At the end of stress the mortality rate of plants:Potentilla fruticosa>Sympegma regelii>Haloxylon ammodendron>Nitraria tangutorum>Tamarix chinesis.3. Under different treatments of salt stress, the leaf water potential of each plant increased with salt concentrations gradually lowering. Under the low concentration of salt stress, the leaf water potential of the diurnal variation is similar to the control, whereas at high concentrations the daily water potential of fruticosa changed irregularly, indicating that salt stress disturbs the physiological metabolism of plants. 4. The impact of salt stress on plants can be described by different value drawled by morning leaf water potential and water potential. Day leaf water potential impact of Tamarix chinesis and nitraria tangutorurmtrs minimum, Haloxylon ammodendron and Sympegma regeliifollowed, Potentilla fruticosais greatest.5. Under salt stress net photosynthetic rate, transpiration rate, stomata conductance, carboxylation efficiency of five plantsdeclined in varying degrees as the salt concentration increased, indicating that salt stress decreased metabolic rate of plant physiology. And under high concentrations of salt stress, the diurnal variation amplitude of these plants’ physiological indicators became lower, which indicates that under severe salt stress, plants maintained at a lower physiological metabolic state to adapt to life.6. With the increase of salt concentration, the daily average net photosynthetic rate and the decline rate of the rate of carboxylation can be drawn, the rate of decline of Tamarix chinesis is the lowest, Nitraria tangutorun followed, Haloxylon cmmodendron and Sympegma regelii followed again, Potentilla fruticosais the highest.7. Under salt stress, because transpiration rate reduced, water use efficiency of plants increased, which is a manifestation of plants to salt stress adaptation. According to changes in water use efficiency, salt tolerance order of five plants is that,Nitraria tangutorum, Tamarisk Haloxylon ammodendron, Sympegma regelii,Potentilla fruticosa from strong to weak.8.According tothe diurnal variation of intercellular CO2 concentration, combined with the net photosynthetic rate, whether a plant has suffered non-stomatal limitations caused by salt stress can be determined. When plants appeared non-stomatal limitation formed by non-environmental factors, according to the size of the salt concentration plants suffered, Potentilla fruticosa showed worst salt tolerance, Haloxylon ammodendron,Sympegma regelii,Tamarix chinesis, Nitraria tangutorumshowed the strongest.9.By net photosynthetic rate, transpiration rate, stomatal conductance and water use efficiency varies with the stress time of growth, can be drawn Tamarix chinesissalt tolerance is strongest, Nitraria tangutorum salt tolerance is strong, Haloxylon ammodendron andSympegma regelii, Hop head salt tolerance is centered and Potentilla fruticosa salt toleranceis worst.In summary, under salt stress the physiological responses of different plants are similar. On the study of the five plants, salt stress has lowest influnce on Tamarix chinesis and Nitraria tangutorum minimum, Haloxylon ammodendron, Sympegma regelii followed, the greatest Potentilla fruticosa.