Effects of Controlled Soil Temperature on Dry Matter Production and Tuber Growth of Eddoe Plants (Colocasia esculenta (L.) Shott).

Abstract

Effects of soil temperature on dry matter production and tuber growth of eddoe plants were examined. Potted plants were grown under non-controlled (N, 25.0-35.8°C), and controlled soil temperatures: low (L, 14.0-17.3°C), medium (M, 19.5-26.3°C) and high (H, 32.5-36.1°C) . Total dry matter and leaf area were the highest in plot N, followed by plot M, whereas those in plots H and L were low. Growth rate of a plant and tuber growth rate were positively correlated with leaf area. Leaf photosynthetic rates showed the maximum value of 12.8 μmol CO2 m-2 s-1 at a root temperature of 27°C, and decreased by about 20% at 17 and 37°C. The tuber yield (daughter tubers) of plots M, H, and L was 74.6, 17.1, and 6.2% of plot N, respectively. Development of leaf area and growth of daughter tubers were promoted under soil temperature of around 25°C in the early period of growth. Increasing the soil temperature by means of mulching is effective in promoting the initial development of leaf area, and hence the growth of daughter tubers in eddoe plants.