Stomatal Response To Drought Stress And Rehydration Of Four Caragana Species

Caragana species are widespread in northwest China. However, species in semiarid areas of Inner Mongolia experience summer and autumn rainfall, In the western region of Inner Mongolia continued in 200-500 mm annual rainfall. Whereas morphologically similar close relatives in arid areas in Xinjiang Province experience wet springs, but hot dry summer, the area continued in about 200 mm annual rainfall. Four seasons are basically uniform precipitation, winter snow, spring melt supply plant growth and persistent drought in summer and autumn in Inner Mongolia. So we speculate that the two distributions of Caragana plants adapt to drought stomatal behavior difference. We choose the four kinds of Caragana plants as the research object and via drought stress and rehydration means to revealed two types of precipitation distribution of Caragana genus stomatal behavior whether there is different. The results are as follows:(1) The leaf water potential decreased continuously in drought period. C. microphylla and C. intermedia have the lowest water potential than C. pruinosa and C. spinosa in Northern Xinjiang distribution.Which explain that Inner Mongolia distribution of species have a stronger ability to endure low water potential.(2) When encountered drought stress, the stomatal conductance and leaf hydraulic conductance of C. microphylla and C. intermedia decreased by 50%、80% corresponding to the water potential values were significant lowest than C. pruinosa and C. spinosa. which show that the Caragana of distribution of Xinjiang is more sensitive to drought than the Caragana of distribution of Inner Mongolia. Based on the differences in stomatal behavior, the photosynthetic rate and transpiration rate decreased with the decrease of water potential.(3) With decreasing of leaf water potential, the increase of proportion of the stomatal conductance closure due to endogenous ABA is more slowly in Inner Mongolia than Xinjiang area. The Caragana of Xinjiang area in order to adapt to the more arid environment through the endogenous ABA to adjust stomatal closure. Which can reduce the transpiration of leaves.(4) After rehydration in-4.0 MPa, The photosynthesis rate,stomatal conductance,transpiration rate of C. microphylla and C. intermedia restored to control level need the desired time were shorter than C.pruinosa and C.spinosa. After rehydration in-6.0 MPa, The photosynthesis rate,stomatal conductance,transpiration rate of C. microphylla and C. intermedia need longer time to recover than-4.0 MPa under four kinds of Caragana. But all can be recovered, which indicates that the plant recovery ability is prolonged with the increase of drought stress.