Different Liriodendron Chinense Liriodendron Hybrid Response To Waterlogging Stress

Uuder the condition of waterlogging stress, the growth, photosynthetic characteristics, physiological characteristics and changes of the intra-structures of the different provenances of Liriodendron chinense and hybrid tulip-tree were analyzed, some results had been gained as the following.(1). After the waterlogging stress for two days, both high growth and survival rate decreased for different provenances of L.chinense and hybrid tulip-tree. Coefficient analysis indicated that, between the stress time and height growth, there was obvious negative correlation for materials from Zhejiang. When waterlogging stress time was longer, the high growth was restrained more seriously, which was similar to the survival rate. Variance analysis showed that, after one- day treatment of waterlogging stress of L.chinense from Zhejiang, there was no significant difference between the control and the treatment in the high growth. But after waterlogging treated for two or three days, there was significant difference between the control and the treatment, the high growth had been restrained obviously.(2). During the process of the waterlogging stress, the stomata conductance, the net photosynthetic rate (Pn) and'the transpiration rate, deceased markedly of different provenances of L.chinense and hybrid tulip-tree. But the opposite result occurred of intercellular CO2 concentration. The intercellular CO2 concentration increased obviously after 48h waterlogging treatment. Coefficient analysis indicated that, between Pn and the stomata conductance, between the transpiration rate and the stomata conductance, there was obvious positive correlation. With different waterlogging time treatments of L. chinense from Zhejiang, the results showed that the stress time was much longer, the restraint to the photosynthesis and the transpiration were more serious.(3). During the course of waterlogging stress, a series of change occurred in the substances and the protective enzymes related with the adversity. The chlorophyll contents decreased continually of L. Chinense and hybrid tulip-tree. But the membrane permeability, protein contents (except for L.chinense from Zhejiang), MDA (malonaldehyde) and the proline contents showed a trend of increasing. The SOD and POD activity both showed increasing trends of L.chinense from Zhejiang and hybrid tulip-tree, different result were in four provenances of L.chinense from Hunan: the SOD activity increased, while POD activity decreased. The stress time was longer, the effects to all kinds of materials and the protective enzymes were more grievous.(4). Under submergence stress, the leaves became faded, yellow, withered andfell down finally. In addition, terminal bud withered and drooped, and a few of terminal bud dried up and died. The aerenchyma was no observed in the cortex of root of L.chinense after waterlogging treatment and control. Under submergence condition, the chloroplast changed from spindle shape to circular shape. The number of chloroplast decreased in the polisade tissue and spongy tissue, the polisade tissue cells became shorter. Meanwhile the cell clearance broadened, cell wall draped. When the leaves became yellow, the polisade tissue cells became much shorter, most chloroplast became circular shape. The number of chloroplast was much less, especially in spongy tissue, chloroplast hardly could been observed.(5). With the treatment of waterlogging, stomata had response to adversity stress at first. Stomata opening degree minished to some degree when leaves withered or lost green. During the process of waterlogging treating, the ultrastructure of chloroplast was damaged to certain degree. At first stroma lamellae and grana lamellae became blurry. With the damage aggravated, the number and cubage of starch grain, osmiothilic material and protein in chloroplast increased, holding most space of the chloroplast, almost the chloroplast was swollen up. Finally, chloroplast disintegrated absolutely. Under waterlogging stress, compared to chloroplast, the structures of mitochondria and nucleus were relat...