Research On Drought Resistance Mechanism Of Amygdalus Pedunculata Pall.

A. pedunculata Pall. is a species of Amygdalus which is considered as a rare and sand-fixtation shrub in the nothswest china with high visual and medicine value. However, the studies on the mechanism of plant drought tolerance were not carried out for A. pedunculata Pall. In this study, the materials we used are leaves, seed and seedling of A. pedunculatus Pall. which were planted in the Maowusu desert, the anatomical structure of leaf, effects of PEG6000 osmotic stress on seed germination, and the physiological responses of seedling to water stress were researched.The results were showed as followed.1. Leaves of A. pedunculata Pall. possessed the traits of xeric morphology and anatomical structure: thicker cuticle, total-palisade tissue, developed vascular tissue, phloem with unique structure, deep stomata and low stomata density.2. Seed germination rate increased at the 100g·L-1PEG6000 stress (-0.2MPa), at -0.4MPa A. pedunculata Pall. can retain the radio of seed germination more than 68%, showing it has strong drought resistance. The high radio of seed germination and the low speed of it is its express of well adapted to water stress.3. Not only contents of chlorophyll, chlorophyll a, chlorophyll b and caroteniod but also the ratio of chla/b, chl/car of leaves increased under light degree soil water stress; The data above has not changed under middle degree soil water stress, all kinds of chlorophyll decreased obviously under heavy soil water stress, and the decrement is chla>chlb>car. Under the PEG stress the changes of the chlorophyll contents are similar to soil water stress.4. Water stress made free water content and relative water content of A. pedunculata Pall. leaves decreased, bound water content, water saturation deficiency and ratio bound water content to free water content increased, leaf water-holding abilities intensify, tissue total water contents kept steady under 10%～25%PEG stress, LWS and MWS.