| The deteriorating ecological environment in Yangtze River and Yellow River, and frequent waterlogging , had caused enormous economic losses. Currently, the lack of planting material of Waterlogging tolerance species leads to most of these wetlands being in the desert or semi-desert state and can not used. Quercus sp. is an excellent landscape tree species in urban and rural greening, and the current study of the oak tree has become a hot spot, but few studies on waterlogging tolerance, particularly in recent years,adaptive research on the foreign oak in China was deficient. Therefore, it's of great significances to research the waterlogging tolerance of Oak and to introduce the adaptive foreign Oak to our country, considering the specific south climate, and select fine Waterlogging oak provenances and clones to enrich plantation tree species and mitigate floods in our country. In this paper, we have studied the change of the external morphology, physiological and biochemical indexes in artificial waterlogging stress of the 6 Quercus species i.e. Q. virgin iana, Q. nigra, Q. shumardii, Q. nuttalli, Q. acutissima and Q. glauca, Q. acutissima and 6 provenances of Q. acutissima. Rongjiang Guizhou, Nanzhao Henan, Jiande Zhejiang, Chizhou Anhui, Lechang Guangzhou, Shangrao Jiangxi. The results showed that:1. Except for Q. glauca, to certain extent, the waterlogging stress improved the biomass accumulation of all the other oaks, and on the stem base there appeared enticel expansion. And to some degree, the leaf damage index can reflect the waterlogging tolerance of tree species.2. To a certain extent, under the waterlogging stress, in order to adapt to hypoxic environment in soil, plant organs changed the allocation of structural biomass, and the ratio of root to shoot, the ratio of leaf mass decreased significantly, while the ratio of stem mass significantly increased. To the perfect Waterlogged species, there was little change in root, but the stem quality were significantly increased, mainly because of the formation of well-developed aerenchyma.3. Proline content and soluble sugar content of leaves were closely related with the waterlogging resistance of Quercus sp. for those two indexes of Quercus sp. with perfect waterlogging resistance were not remarkable comparing with the control test, and in the late stage of the waterlogging they were almost equal to the value of the control test. However, for Quercus sp. which can not withstand waterlogging , the Proline and soluble sugar content of leaves increased as time went on.4. Under the waterlogged stress, the highest value of MDA content in different oak leaves occurred at different times compared to the control test. And the occurring time of Q. virginiana, Q. nigra, Q. shumardii were respectively 7th day, 14th day and 28th day after being treated with waterlogging , and in the late growth period the rate of the increase reduced. Q. acutissima, Q. glauca appeared in the late period and this fact could be used to judge the ability of waterlogging tolerance of tree species.5. Through the principal component analysis of Quercus sp. with 16 indicators, and the results showed that the growth and comprehensive morphologic factors such as biomass and the leaf damage index and physiological regulators such as soluble protein, soluble sugar, proline could be combined to establish an evaluation system for waterlogging tolerance. The descending order of Waterlogged tolerance of 6 tree species was: Q. nuttallii > Q. virginiana > Q. nigra > Q. shumardii > Q. acutissima> Q. glauca.6. According to the growth, physiological and biochemical changes of Q. acutissima provenances under waterlogging stress, the Q.acutissima in Shangrao and Jiande were initially proved to have a certain high waterlogging tolerance. |
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