| Eucommia ulmoides oliver.(Eulmoiaceae, Eueommia) is a economic tree species endemic to China It has not only graceful shape for greening ,but also high economic value .In this essay ,by taking the culture method of nutrient solution with different salt concentration (NaCI w/v) and Prunus persica Batsch as control , salt tolerance of E. ulmoides has been investigated in two aspects of microstructure and physiological indexes. The results of microstructure observation showed that E. ulmoides seedlings living in saline environment have the follow characteristics: (l)Thick cuticle ,obvious stomatic chamber and orderly arrangement of epidermal cells of the leaves are favorable for reducing water evaporation. There is vesicular structure in palisade cells. Some locate in the center of the cells, the others are in connect with plasmalemma directly , even blending with membrane and forming exoeytosis. (2) There are obvious ergastic substance in endodermis cells of stem, among which much of these substance may be starch grains that is useful in increasing cell osmotic pressure and improving obsotbing and keeping water ablities. The results of physiological indexes analysis of E. ulmoides and P persica under different salt stress demostrated that cell membrane permeability(MP) of both species increased with the increasing of NaCl concentration, contents of Na and C[ showed the same intendency, but the increasing degree of the three indexes is lower in E. Ulmoides than in P persica; Proline(Pro)content firstly increased rapidly but late decreased as the stress intensity extended, but Pro content of E. ulmoides is obviously higher than that of P persica; Soluble sugar (SS) of F. ulm aides is higher than that of control tree under low salt concentration ,but SS of P persica tends to increase and that of E. ulmoides tends to stable with salt stress increasing; Changes of chlorophyll (CHI) content and carotinoid (CAR) content appeared wavy line and both species are peak and trough corresponding. Malondialdegyde (MDA) content of both is opposite to each other and P persica is by far higher than E. u/mo ides ; Catalase (CAT) activity of E. ulmoides increased and changes of that of P. persica is not obvious; No distinct difference of KVNa~ under different salt stress. Though correlation analysis about physiological indexes, the results showed: MP increase was accompanied by the decrease of content of MDA and the increase of content of Pro; There was negative relationship between the increase of Pro content and MDA content, significant or extremely significant negative correlation between the increase of Pro and the degradation of CH]; There was significant or extremely significant positive relation between SS content and MP.The changes of the same physiological index in E. ulmoides and P. persica in different salt stress were determined: 1. Plants adapted the salt habitat in different ways, in exception of their heredities. Different plants resist the effect of saline by different ways at the same or different conditions. 2. Judging with physiological indexes comprehensively , E. ulmoides has not only salt-resistant abilities, but also higher salt resistance than P persica in many aspects.
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