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Abstract [Objective] In order to explore the effects of phenolic acid self-toxic substances on the growth and photosynthetic characteristics of Pugionium cornutum (L.) Gaertn. and P .dolabratum Maxim., and to provide a theoretical basis for the protection, development, and utilization of wild resources of P . cornutum and P .dolabratum . [Methods] A pot experiment was conducted with P . cornutum and P .dolabratum seedlings. The experiment focused on two self-toxic substances, cinnamic acid and phthalic acid, and the seedlings were treated with varying concentrations of 0, 0.01, 0.1, 1, and 10 mmol/L. The aim was to observe the effects of these concentrations on seedling growth, chlorophyll content, chlorophyll fluorescence parameters, and gas exchange parameters. [Results] (1) Cinnamic acid and phthalic acid promoted seedling growth of P . cornatum at low concentrations and inhibited seedling growth at high concentrations. The growth of P . dolabratum was inhibited. 10 mmol/L cinnamic acid and phthalic acid treatment had the most significant growth inhibition effect on Pugionium Gaertn. (2) Chl a, Chl b, and Chl a+b content of these two species were decreased in different degrees after treatment with different concentrations of cinnamic acid and phthalic acid. (3) Pn, Tr, and Gs of these two species at 10 mmol/L were significantly lower than that of the control, while Ci had no significant change. The main cause for the reduction of photosynthetic rate was non-stomatal factors. (4) Fv/Fm, ФPSⅡ , and qP of these two species at 10 mmol/L were significantly lower than that of the control and NPQ was significantly higher than control. [Conclusion] The high concentrations of phthalic acid and cinnamic acid inhibited photosynthesis and reduced photosynthetic rate in seedlings, resulting in the impairment of PSⅡ reaction center activity and opening in leaves of these two species, which affected the growth of Pugionium Gaertn.. In addition, the effects of cinnamic acid and phthalic acid on photosynthetic characteristics of Pugionium Gaertn. were different, due to different plant and stress types. |
