Study On Physiological Mechanism Of Adatation Of Nitratia Under Saline-alkali Stress

Nitraria L.is a shurb of zygophyllaceae, is the Tertiary Period relic plant. Nitraria L. is the fine cover plant anti saline-alkaline and the sand fixation pioneer plant which has strong adaptability, strong salt-tolerance, strong covering power.In this experiment testing,using Nitraria tangutorum and Nitraria sibirica as experiment materials,and it is using four single salt and different proportions complex saline-alkali stress, and it carries on deeply research of the changes of saline-alkali stress on physiological adaptability of Nitraria L., bases on combing predecessor's research methods and results. It provides bases for researching salt-tolerant adaptability of Nitraria L.and popularizing Nitraria L. in saline-alkali area and riching urban greening tree species.This article utilized the plant physiological ecological research methods to analyze the physiology characteristic's responds of two species of Nitraria L. under saline-alkali stress with different salinity and alkalinity. The results indicated that:1. The research of saline-alkali stress on growth characteristics of two species of Nitraria L. showed that: A certain saline-alkali stress would promote chlorophyll synthesis of Nitraria L., and at the same time increase their root vitality. Just only when salinity was higher than 300mmol/L, pH>10.59, the chlorophyll contents decreased slightly and along with the root vitality decline, it began to affect Nitraria's normal anabolism; For four single salt stress, only under 400mmol/LNa2CO3, pH11.68 treatments , chlorophyll content of Nitraria L is slightly lower than the control, and the root activity is still higher than the control, the two species of Nitraria L prickly little effect on normal growth..2. The research of saline-alkali stress on membrane systems of two species of Nitraria L. showed that: Under complex saline-alkali and four sigle salt stress, the electrolyte leakage rates in leaves of two species of Nitraria L. increased, resulted in membrane lipid peroxidation produce - MDA contents increased, it showed that saline-alkali stress made certain damage to membrane systems. Under saline-alkali stess, the electrolyte leakage rates were high, but the structure of leaves didn't change obviously, the plants were alive, it could clearly be seen, the two species of Nitraria L. had strong salt tolerance.3. The research of saline-alkali stress on osmoregulation substances of two species of Nitraria L. showed that: Under the complex saline-alkali stress of salinity 300mmol/L, pH<10.59, the contents of soluble sugar, soluble protein and proline increased in leaves of two species of Nitraria L.; Under the four salt stress of salinity 400mmol/L, pH<11.69, the contents of Osmotic adjustment increased in leaves of two species of Nitraria L.also, it shows: under the different salt stress, two species of Nitraria L. are increasing the content of osmolytes adjustment for increasing cell concentration,and provided leaves'normal water potential to enhance Nitraria's saline-alkali resistance ability. The increase of osmoregulation substance content has a positive significance to improve Nitraria's salt tolerance.4. The research of saline-alkali stress on protective enzyme systems of two species of Nitraria L. showed that: Under the complex saline-alkali stress, two species Nitraria L. of protective enzymes decreased with the increase of salinity and pH increased ,and then while in single-salt stress, with the increase of salinity and pH, SOD activity and CAT activity maintain the upward trend, POD activity increased firstly and then decreased to a change in the different salt stress conditions, the Nitraria L. cells to free radical protective enzyme system remains at a low level in order to prevent free radical cellinjury, are Nitraria L. thorn can be adapted to high saline environment salinity stress.5. Than the single-salt stress, alkaline stress on plants more dangerous, not only by physiological changes of Nitraria L degree of concentration, pH is also an important factors. Carried on linear regression analysis to salinity, pH, [CO32-] and [HCO3-] four stress factors which heavily influenced Nitraria's growth, the chlorophyll content and root vitality in Nitraria weren't remarkable linear with four stress factors, and the other physiological biological indices with the four stress factors all showed a linear relationship (correlation coefficient R2>0.75), sorting to four stress factors, salinity was the most important stress factor.