| Leymus chinensis is perennial, rhizome grass that has capacity of tolerance to drought, leanness, and salt- alkali. Leymus chinensis with strongly adaptability and widely ecological plasticity can is adaptive to complicated habitat conditions. Leymus chinensis in grey-green color and yellow-green color is interlaced with spots in the distribution section. Some scholars called two color Leymus chinensis as ecotypes or divergent types ago. But they did not brought forword sufficient evidences about ecotype differentiation and dominant factor, all studies did not proved that two color Leymus chinensis have been differentiation into two ecotypes. Two ecotypes belong to one species according to taxology. Nobody had compartmentalized them to variation or change type. In individual and population levels, my paper firstly proved that two color Leymus chinensis had physiological divergent differentiation, defined that dominant factor of differentiation was salt-alkali in the soil. Leymus chinensis in grey-green color and yellow-green color was respectively defined with grey-green ecotype and yellow-green ecotype. There are power evidences about theory for making sure two ecotypes Leymus chinensis in my study.Physiological ecology studies in individual and population levels approved that the physiological characteristics had be obviously divergent adaptive differentiation with genetical qualities. Two ecotypes had some capacity of adaptation. The stronger tolerance of grey-green ecotype and the weaker tolerance of yellow-green ecotype to salt-alkali and drought were accordingly adaptive reaction to different salt-alkali habitats in long term. Above all, the differentiation of two ecotype populations was caused by many environmental factors, and then the salt-alkali of soil was the most dominant factor. Two ecotypes were due to soil ecotype, which showed ecological adaptation and evolution meaning. The differences of two ecotypes were not obvious on the aspect of population characteristics, age structure, reproduction characteristics, rule of propagation and module growth, and so on. Changes in value in different habitats were the result ofecological adaptation to different habitats, which was on the range of ecological plasticity. Two ecotype populations take the same strategy during surviving and development.Some physiological indexes were determined in two ecotypes Leymus chinensis under salt-alkali, PEG, CO2 stress. The content of chlorophyll, net photosynthesis rate, WUE, the accumulative rate of free proline and Na+ were higher in grey-green ecotype than in yellow-green ecology. On the other hand, Ca/Cb, the leakage rate of electrolyte of leaves, transpiration rate, stomata conductance, AQY, decline rate of Na/K were lower in grey-green ecotype than in yellow-green ecology. The relationships between and the concentration of stress were significant or obviously significant. The differences of these physiological indexes between two ecotypes were also significant or obviously significant. Leymus chinensis is adaptive to execrable habitat in the way of stress tolerance. It increases the capacity of penetrate adjustment with accumulating the matter of penetrate adjustment, which is relate to the capacity of resistance and adaptability. The result showed that the capacities of penetrate adjustment, matter production and adaptability were stronger in grey-green ecotype than in yellow-green ecotype. There were differentiations between two ecotypes on the aspects of physiological characteristics and primary productivity during the process of adapting different habitats. High concentration of CO2 played a role like fertilizing, which could increase photosynthesis and matter production. But fertilizing CO2 cannot compensate the loss that was brought by drought in grievous drought habitat.Water content rate of tiller, the content of chlorophyll and nitrogen were more in grey-green ecotype natural population than in yellow-green ecotype, while water potential and the leakage rate of electrolyte were fewer. There were differences betw... |
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