Lanthanum chloride enhances the photosynthetic characteristics and increases konjac glucomannan contents in Amorphophallus sinensis Belval

Lanthanum (La) has been used as agricultural inputs in order to enhance yield and improve crop quality. However, little is known about the effect of La on the photosynthesis and growth of Amorphophallus sinensis, a worldwide food source. The effects of La on the photosynthetic and chlorophyll fluorescence parameters, photosynthetic pigments, corm yield, and konjac glucomannan (KGM) of Amorphophallus sinensis were investigated via field experiments. The leaves were sprayed with different concentrations of LaCl3 (20, 80, 160, and 240 mg L-1). The results exhibited an increasing effect of LaCl3 on photosynthetic rate, stomatal conductance, intercellular CO2 concentration, chlorophyll fluorescence parameters, photosynthetic pigments, corm yield, and KGM, when concentration was between 20 and 240 mg L-1, and the most effective concentration was 160 mg L-1. Therefore, moderate LaCl3 concentration may increase yield of Amorphophallus sinensis by enhancing the photosynthetic efficiency, increasing the corm yield, and KGM contents.