Physiological water strategy of Artemisia ordosica around soil threshold of drought |
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Authors: | Pingping Xue and Xingdong He |
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Institution: | (1) College of Life Sciences, Nankai University, Tianjin, 300071, China |
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Abstract: | The mechanism for plants around the soil threshold of drought (close to the soil wilting water content) is a problem that
needs to be further explored. In this paper, Artemisia ordosica, which grows in the Tengri Desert, was selected to analyze the changes in the plant water potentials in the soil-plant-atmosphere
continuum (SPAC), the water contents in the roots, shoots and leaves of A. ordosica, and the indices in enzymatic and non-enzymatic systems. Based on the statistics, we discussed the water physiology mechanism
around the soil drought threshold. The results show that, around the soil drought threshold, besides absorbing and transporting
water, the roots could serve as temporary water reservoirs that enable A. ordosica to continue to transport the SPAC water and survive severe drought. As drought becomes more severe, the activity of superoxide
dismutase (SOD) and catalase (CAT) increases and they have significant correlations with the tissue water content. The activity
of peroxidase (POD) decreases and it has no significant correlation with the tissue water content. During daytime, when temperature
is high, the soluble sugar does not participate in the osmotic adjustment but eliminate the active oxygen free radicals. Thus,
around the soil threshold of drought, A. ordosica maintains a physiological water metabolism by harmonizing water itself and eliminate the active oxygen and the free radicals
by the joint efforts of enzymatic and nonenzymatic systems. |
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Keywords: | Artemisia ordosica soil drought SPAC water potential protective enzyme water physiology |
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