不同光斑环境对海南凤仙花叶片解剖结构及光合特性的影响OA

To investigate the response of the extremely small population species Impatiens hainanensis to different sunfleck environments,this study used six-month-old I.hainanensis as experimental materials.Based on the light environment thresholds of natural habitats,three treatments were established:20%light transmission(control),20%sunflecks,and 50%sunflecks environments.Growth parameters,leaf anatomical structure,and photosynthetic characteristics were comparatively analyzed.The results showed that:(1)The sunflecks environments significantly promoted both plant height and crown width growth of I.hainanensis,while the ground diameter remained unaffected.(2)The 50%sunflecks environment notably increased stomatal density.(3)After 40 days of sunflecks treatment,the leaf structure of I.hainanensis under the 50%sunflecks environment exhibited superior leaf thickness and mesophyll tissue development compared to the 20%sunflecks area,while other structural indicators remained stable.(4)Prolonged exposure to the 50%sunflecks environment was more conducive to maintaining photosynthetic pigment content in I.hainanensis,particularly in promoting carotenoid accumulation.(5)Sustained exposure to the 50%sunflecks environment consistently and significantly enhanced the net photosynthetic rate of I.hainanensis,demonstrating clear advantages in improving stomatal conductance and transpiration rate.(6)With the extension of sunflecks treatment duration,the MDA content exhibited an initial increase followed by a decrease.In later stages,no significant membrane lipid peroxidation damage was observed in I.hainanensis,indicating its ability to adapt to various sunflecks environments over extended periods without suffering oxidative stress.Research indicates that I.hainanensis adapts to different sunflecks environments by regulating leaf structure and photosynthetic characteristics.Under 50%sunflecks exposure,it can significantly optimize leaf anatomical structure and photosynthetic performance,achieving optimal growth status.This study provides critical illumination management guidelines for the introduction,domestication,artificial breeding,and population restoration of I.hainanensis.Simultaneously,it offers important scientific basis for in-depth understanding of sunflecks adaptation in limestone understory plants and the conservation and management of understory vegetation in tropical rainforests.