Mineral Nutrients and Plant-Fungal Interaction in Cocoa Trees (Theobroma cacao L.)

An infection of the fungus Moniliophthora perniciosa in cocoa trees reduces productivity of the plant. In this study, the concentrations of mineral nutrients in healthy leaves and in leaves of vegetative broom of the cocoa plant were determined, and the relationship between the disease and the nutritional composition of the leaves was assessed. The samples were analyzed using the wet digestion method and the concentrations were determined by inductively coupled plasma optical emission spectrometry and the Kjeldahl method. Results indicate that leaves of vegetative broom have lower concentrations of Ca, Mg, S, Fe, Mn, and Ni than healthy leaves. Concentrations of P and Cu were lower in healthy leaves and higher in leaves of vegetative broom. In contrast, concentrations of K, N, and Zn were the same for both types of leaves. In short, plant-fungal interaction was reflected in the nutritional composition of the leaves, demonstrated by the differences in nutrient concentrations between healthy and infected leaf tissue.可可植株被真菌可可瘤顶孢霉(Moniliophthora perniciosa)侵染后，会降低其生产能力。本研究测定了可可健康叶片与营养丛枝(vegetative broom)叶片的矿质养分浓度，并评估了该病害与叶片营养组成之间的关联。样品采用湿消解法(wet digestion method)进行前处理，通过电感耦合等离子体光发射光谱法(inductively coupled plasma optical emission spectrometry)与凯氏定氮法(Kjeldahl method)测定养分浓度。研究结果显示，营养丛枝叶片的钙(Ca)、镁(Mg)、硫(S)、铁(Fe)、锰(Mn)及镍(Ni)浓度均低于健康叶片；磷(P)与铜(Cu)的浓度则在健康叶片中更低，在营养丛枝叶片中更高。与之相反，钾(K)、氮(N)与锌(Zn)的浓度在两类叶片中保持一致。简言之，植株与真菌的互作可通过叶片的营养组成体现，健康叶片与侵染组织间的养分浓度差异即为有力佐证。