DRY MATTER PRODUCTION AND NUTRIENT CONTENT OF LONGAN GROWN ON AN ACID ULTISOL

Little is known about the adaptability of longan (Dimocarpus longan) to acidic soils high in aluminum (Al). A two-year field study was conducted to determine the effects of various levels of soil Al on dry matter production, plant growth and nutrient content in shoots of four cultivars of longan. Soil Al and cultivars were statistically different for all variables measured in the study. Total leaf, petiole, stem and root dry weights significantly decreased at soil Al concentrations ranging from 5.1 to 12.1 cmol kg−1 but this reduction was of a smaller magnitude in roots than in other organs. Increments in soil Al resulted in a significant reduction in the concentration of leaf Ca and a significant increase in leaf Al in all cultivars. Shoot content of N, P, K, Ca, Mg, Fe, Mn and Al declined with increase in soil Al. The result of this study demonstrates that longan is highly susceptible to acid soils.