光照强度驱动典型阴生植物三七的生理生态响应特征

为探究阴生植物三七(Panax notoginseng)对不同光照强度的生理生态响应特征,研究5种透光率(46.5% LT、21.8% LT、9.70% LT、5.10% LT、2.80% LT)下三七生理、形态和生长等各项指标的变化特征,并对其相关指标进行相关性、可塑性和主成分分析。结果表明:三七在高光(46.5% LT和21.8% LT)和低光(5.10% LT和2.80% LT)条件下各形态特征(株高、茎粗、单株叶面积)、生物量及相对生长速率(RGR)均有所降低;随着光照强度的降低,根生物量比(RMR)、最大净光合速率(P_n-max)、气孔导度(G_s)、光补偿点(LCP)和暗呼吸速率(R_d)都随之下降,而叶面积比(LAR)、比叶面积(SLA)、茎生物量比(SMR)和叶生物量比(LMR)却呈现升高的趋势。这些变化能够减少三七在高光下的光能捕获及消耗,而低光下的光能捕获和消耗则会得到加强。此外,阴生植物三七的形态特征表型可塑性指数均小于0.5,而光合生理(P_n-max、G_s、LCP、R_d)、LAR和根部生物量的表型可塑性指数则大于0.5,其可塑性较强,且P_n-max、G_s、LCP与RGR的相关系数分别高达0.581、0.558、0.574,这些结果表明光照强度驱动三七的响应特征主要为光合生理特性、LAR和根部生物量的变化。研究还发现三七在10%左右的透光率下生长发育较好。而在低光条件下,三七主要采取保守策略进行缓慢的碳获取和碳消耗,高光条件下则主要采取快速碳获取和碳消耗的冒险策略。研究阐明了三七对不同光照环境的响应策略,为三七的优质高效种植提供理论依据。

Ecophysiological characteristics of a typically shade-tolerant species Panax notoginseng in response to different light intensities

This paper aims to explore the ecophysiological characteristics of a typically shade-tolerant species Panax notoginseng in response to different light intensities. Different light levels were applied to P. notoginseng. The physiological traits, morphological traits and growth indicators were comparatively analyzed in the plants grown under 46.5% light transmittance (LT), 21.8% LT, 9.70% LT, 5.10% LT and 2.80% LT. Correlations among the ecophysiological characteristics, plasticity indices and principal component analysis (PCA) were conducted in the study. The results showed that morphological characteristics (plant height, stem thickness, leaf area per plant), biomass and relative growth rate (RGR) of P. notoginseng were decreased under high light condition (46.5% LT and 21.8% LT) and low light condition (5.10% LT and 2.80% LT). With the decrease of light intensity, root biomass ratio (RMR), maximum net photosynthetic rate (P_n-max), stomatal conductance (G_s), light compensation point (LCP) and dark respiration rate (R_d) declined, while leaf area ratio (LAR), specific leaf area (SLA), stem biomass ratio (SMR) and leaf biomass ratio (LMR) showed an increasing trend. These changes were able to reduce light energy capture and light energy consumption of P. notoginseng in high light condition, while light energy capture and consumption in low light condition were enhanced. In addition, the phenotypic plasticity indices of morphological characteristics of shade-tolerant species P. notoginseng were less than 0.5, while the phenotypic plasticity indices of photosynthetic physiology (P_n-max, G_s, LCP, R_d), LAR and root biomass were greater than 0.5, and the plasticity indices were 0.581, 0.558 and 0.574 for P_n-max, G_s and LCP, respectively. The results indicated that photosynthetic physiological characteristics, LAR and root biomass were most responsive to light intensity. Moreover, studies have found that approximately 10% LT was suitable for the growth of P. notoginseng. In a word, under low light conditions, P. notoginseng mainly adopts a conservative strategy for decelerating carbon acquisition and carbon consumption, while under high light conditions, P. notoginseng mainly adopts an adventurous strategy for rapid carbon acquisition and carbon consumption. The study elucidates the adaption strategies of P. notoginseng in response to different light intensities and provides a theoretical basis for the high-quality and efficient cultivation of P. notoginseng.