Studies On The Ultra-Structure And Physiological Characteristic Of Citrus Under Water Stress

Citrus is one of the most important fruit crops for its rich nutrient and economic values. Citrus is mainly distributed over 135 tropical and subtropical countries. Water-stress which can disrupt crops' water balance and reduce production is a meteorological disaster that caused by long-term rainless or less raining. Even the area where rainfall is plentiful also easy involve in the drought disaster because of uneven rainfall and abnormal climate. Citrus is easier affected by water stress due to they mainly plant on hilly land. So far the basic and systematic research on mechanism of water stress in woody plant is very limited compared to that in other crops like maize, wheat and rice. Though, there are many researches which focus on some Physiological index of single variety, the mechanism of water stress is regulated by polygenes, the regulated mechanism of water stress is much different among different spices and the expression of plant resistance also variety in different space-time, it can not make a systematic analysis and clarify a drought-resistance mechanism. Hence, the root and leaf ultra-structure, photosynthesis, endogenous polyamines and phytohormones levels were systematically studied by using citrange[C. citrange S], Sha-tian pomelo[C.grandis (L) Osbeck], Yamasitaka[C.unshiu Marc], Newhall orange[C.sinensis (L) Osbeck], trifoliate orange[P. trifoliata (L) Raf] as materials to reveal the mechanism of water stress of citrus. The results are as follows.1. Water stress can significantly affect root, leaf and chloroplast ultra-structure. The damage degree of ultra-structure is increased by water stress. Under well water condition, the cell structure of root and leaf are in good shape, the typical convex lens composed of alternately arranged grana and stroma lamellae, the double outer envelopes and intima systems are observed clearly. But under water stress, a series of chloroplast configuration...