| Picea mongolica is a rare species in the world which belongs to pinaceae picea evergreen tree, a forest type of semi-arid grassland area. It is also the construction of the "Three-North"(North-West, North and North-East China) shelterbelt. It is distributed exclusively in the eastern edge of the fixed sand dunes in Hunshandake Sandy Land, China. The intraspecific differentiation of Picea mongolica differentiation into three kinds of ecotype, they are P. mongolica f. purpurea (purple), P. mongolica f. rubra (red), and P. mongolica f. viridis (green). Since the global warming, drought becomes one of the main stress factors in plant growth and distribution. According to statistics, around the world, agriculture and social damage caused by drought and water shortage equal to the sum of the damage caused by other kinds of natural disasters. Therefore, to research how plants resist and adaptation drought has great significance in practice.Calcium is one of the necessary nutrient elements for plant growth which plays an important role in the structure and physiological function of plant cell. And as second messenger, calcium can modulation the activeness of enzymes and affect the functions of cells with calcium-adjust material (CaM). Calcium has an important effect on the drought resistance of plant.With potted Picea mongolica as experimental materials, using plant nutrient solution with different concentration of CaCl2(Ommol/L、5mmol/L、10mmol/L20mmo1/L、30mmol/L) and different percentage of PEG-6000(0%,15%,30%) deal with three ecotypes of Picea mongolica seedlings. And to measure leaf relative water content, soluble protein content, MDA content and chlorophyll content, to observe the influence of calcium on the physiological characteristics under drought stress, and to compare the ecological impact of three ecotypes of Picea mongolica seedlings. According to the above indicators that calcium influence on Picea mongolica under drought resistance, and to gain a better concentration of calcium which can enhance the power of Picea mongolica resist drought. The study results show that:under drought stress, the appropriate concentration of Ca2+(below20mmol/L) can improve the leaf relative water content, soluble protein content and chlorophyll content of Picea mongolica seedlings, and reduce MDA content of Picea mongolica seedlings. These showed that the proper concentration of Ca2+can improve leaf water retention ability, enhance the photosynthesis, reduce the leaf membrane lipid peroxide level and maintain leaf physiological activities, so as to improve the drought resistance of Picea mongolica seedlings. The ability of drought resistant of three ecotypes of Picea mongolica is different, the drought resistance of P. mongolica f. purpurea is strongest, P. mongolica f. viridis is weakest, and P. mongolica f. rubrais is between them. The test also confirmed that a low concentration of Ca2+can improve the drought resistance of Picea mongolica significantly, the high concentration of Ca2+can’t improve the drought resistance significantly; even reduce its drought resistance because of hypertonic. This study provides scientific guidance for application calcium which has significance in theory and practice. |
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