Guangxi Zhiwu (Mar 2023)
Variation and correlation of photosynthetic traits of eight adaptive plants in karst region of Southwest Guangxi
Abstract
In order to explore the photosynthetic physiological adaptation mechanism of karst plant, the leaf photosythetic parameters of eight karst adaptable plants in Pingguo City, Guangxi were detected and analyzed, including net photosynthetic rate (Pn), stomatal conductivity (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), water use efficiency (WUE) and stomatal limitation value (Ls), by using Li-6400XT portable photosynthesis system. Statistical methods, such as Pearson correlation analysis, principal component analysis (PCA), and permutational multivariate analysis of variance (PERMANOVA) were also used in this study. The results were as follows: (1) Six photosynthetic parameters had different variations within and between species, and all the intraspecific variations were greater than the interspecific. (2) Change of Gs and Tr mainly originated from interspecific variation (46.72% - 49.76%), while that of Pn, Ci, WUE and Ls mainly from intraspecific variation (48.66% - 64.50%). At the life form level, the intraspecific variations of Pn, Gs and Tr of evergreen plants were less than those of deciduous plants, but the intraspecific variation of Ci, WUE and Ls of evergreen plants was higher. (3) Interspecific variations of all the parameters of deciduous plants were greater than those of evergreen plants. (4) Gs variation was the greatest both at the intraspecific and the interspecific levels, followed by Tr and Pn, then Ls and WUE, and Ci variation were the least. There were significant positive correlations among Pn, Gs and Tr (P<0.01). Ls was significantly positively correlated with WUE (P<0.05), but negatively with Gs and Ci (P<0.05). The correlations among these photosynthetic parameters are basically consistent with the global scale, which reflects the diverse trade-off strategies of plants to environment resources. The results also verified the leaf economics spectrum (LES) of karst plant. (5) Evergreen plants were located at the slow investment-return end of the LES with high values of Ls, WUE and low values of Gs, Tr, Ci and Pn. On the contrary, deciduous plants were located at the quick investment-return end of the LES with low value of WUE and high value of Pn and Tr. The results reflect karst plant adapt to changing environment with different adaptation strategies by trade-offs or co-ordinations among traits, and provide scientific basis for selecting adaptive tree species and accelerating the succession process of vegetation restoration in the karst area.
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