Plant biometric characterization and leaf micromorphometry of Talinum triangulare (Jacq.) Willd cultivated under shade

ABSTRACT Talinum triangulare (Jacq.) Willd, known as Ceylon spinach, Surinam purslane, or waterleaf, is cultivated for medicinal and food purposes. Among environmental factors, light is an important regulator of primary production, contributing to plant growth. However, the success of each plant species depends on its morphoanatomical responses to light. The aim of this study was to determine whether T. triangulare leaf micromorphometry is affected when grown in full sun and under shade, and if so, which plant biometric variables are affected. T. triangulare cultivation was tested in beds arranged in blocks under shade levels of 0, 18, 30, and 50%. Each bed was considered a basic experimental unit, totaling four replications per treatment. Plant height, stem diameter, leaf area, leaf fresh weight, stem fresh weight, specific leaf area, leaf area ratio, abaxial epidermis, and mesophyll thickness were higher as shade levels increased. However, there was a decrease in the number of leaves, root to shoot ratio, stomatal density on abaxial and adaxial surfaces, and palisade parenchyma thickness. Nevertheless, root length, leaf and stem dry weights, leaf weight ratio, adaxial stomatal index, adaxial epidermis, and spongy parenchyma thickness remained constant. Plants responded differently to shade, with morphological and anatomical changes, suggesting a phenotypic plasticity and raising the possibility of being grown both in shaded environments and in full sunlight.

摘要：土人参（*Talinum triangulare* (Jacq.) Willd.，别名锡兰菠菜、苏里南马齿苋或水叶菜）兼具药用与食用价值，常被人工栽培。在各类环境因子中，光照是初级生产力的重要调控因子，对植物生长具有显著促进作用。然而，不同植物物种的生长成效取决于其对光照条件的形态解剖学响应。本研究旨在探究：土人参的叶片微形态特征在全光照与遮阴环境下是否会发生改变；若发生改变，则哪些植物生物计量学变量会受到影响。本研究设置0%、18%、30%、50%四个遮阴梯度，采用区组设计搭建栽培床开展土人参栽培试验，每个栽培床为基本实验单元，每个处理设置4次重复。结果显示，随着遮阴梯度升高，植株株高、茎粗、叶面积、叶鲜重、茎鲜重、比叶面积（specific leaf area）、叶面积比（leaf area ratio）、远轴表皮（abaxial epidermis）厚度与叶肉厚度均显著提升；但与此同时，叶片数量、根冠比（root to shoot ratio）、上下表皮的气孔密度以及栅栏薄壁组织（palisade parenchyma）厚度均出现下降。而根长、茎叶干重、叶干重比、近轴表皮（adaxial epidermis）气孔指数、上表皮厚度以及海绵薄壁组织（spongy parenchyma）厚度则未发生显著变化。土人参对遮阴环境呈现出差异化响应，伴随形态与解剖结构的适应性改变，这表明其具有表型可塑性，同时也提示该物种既可在遮阴环境下栽培，亦可在全光照条件下种植。