The Physiology And Ultrastructure Of Five Species Under Drought Stress

The effect of soil drought stress on Quercus acutissma Carruth, Dalbergia hupeana Hance, Pistacia chinensis, Pinus elliottii and Celtis sinesis Pers was studied and observed in this paper, morphology indicator, photosynthetic indicator, fluorescence parameters, leave's anatomical structure are surveyed during the experiment, the results are as follows,Morphology indicators of the five species' relative growth rate and dry weight of the roots, stems and leaves decreased significantly. The results are as follows:Celtis sinesis Pers> Dalbergia hupeana Hance> Pistacia chinensis>Quercus acutissima Carruth> Pinus elliottii.With the aggravation of the drought stress, the Pn, Gs and Tr of the five species decreased significantly. The Ci first decreased, and then increased and accumulated. Photosynthetic capacities are as follows:Pinus elliottii and Quercus acutissima Carruth are the strongest. Dalbergia hupeana Hance and Pistacia chinensis are medium. Celtis sinesis Pers is the weakest.The florescence parameters of the five species are as follows:Fo increased while Fm, Fv /Fm, PSⅡdecreased. The result of the decreased is Celtis sinesis Pers> Dalbergia hupeana Hance> Pistacia chinensis> Quercus acutissima Carruth> Pinus elliottii.Anatomical structures of the five species' leaves are altered under drought stress. The stomatal densities of all species increased while the length and width decreased respectively. The sequence of the change is Pinus elliottii> Quercus acutissima Carruth >Pistacia chinensis> Dalbergia hupeana Hance> Celtis sinesis Pers.Under the condition of light drought stress, the ultra structure of Pinus elliottii was not damaged. The mitochondria of Quercus acutissma Carruth remain normal, but the chloroplasts expanded. For Celtis sinesis Pers, plasmolyses occurred and the mitochondria and the chloroplasts damaged. Under the condition of heavy drought stress, the mitochondria of Pinus elliottii and Quercus acutissima Carruth were degraded, and the chloroplasts were not adhered to the cell walls. For Pistacia chinensis and Dalbergia hupeana Hance, plasmolyses occurred and the mitochondria and the chloroplasts damaged severely. The results showed that the drought resistance of the five plants could be divided into three degree:the Pinus elliottii and the Quercus acutissima Carruth have strong drought resistance, the Pistacia chinensis and the Dalbergia hupeana Hance have moderate drought resistance while the Celtis sinesis Pers has the weakest drought resistance.According to the five species' survival rate and after evaluating all the indices of the drought resistance and physiological adaptation of the five species with membership function, the sequence of drought resistance of the five species is as follows, Pinus elliottii> Quercus acutissima Carruth>Pistacia chinensis> Dalbergia hupeana Hance> Celtis sinesis Pers.