Using Soil Improvement Materials for Enhancing Drought Tolerance of Rubber Plant

抄録

A study on the effects of applying a type of clay minerals on drought tolerance of rubber plant was carried out by incorporating bentonite at 0, 2, 4, and 8 percent w/w into loamy sand soil (Roi-et series). Factorial arrangement in CRD (complete randomized design) with 3 replications was performed in this research study. It was found that mixing bentonite 0-16 percent w/w with sugarcane bagasse, coconut fluff, peanut husk, black-burned rice husk, and fresh rice husk caused the water holding capacity to be in the ranges of 41.50-58.88, 44.3-105.0, 9.1-20.4, 128.6-154.2, and 3.1-21.3 percent, respectively. After 14 days of application for rubber varieties RRIM600 and RRIT251 grown on loamy sand, using bentonite 0, 2, 4, and 8 percent w/w caused the drought tolerance without irrigation to be 31-35 and 29-47 days, respectively. It was also found that small and medium sizes of rubber seedlings showed higher drought tolerance than those of big sizes because they still survived without irrigation 40-48, and 38-43 days, respectively. All sizes of RRIM600 seedling started wilting at moisture contents 4.9-5.9 percent and then showed permanent wilting at 3.30-3.39 percent w/w. Clay minerals used as basal application under field experiment significantly increased drought tolerance of young RRIM600 to be 158 days after planting whereas no application on the rubber tree could stand by the age of 92-135 days or averagely 111 days after planting. Increasing 15-15-15 concentration as basal fertilizer by the rates 100, 200, 400, and 600 g/plant significantly accelerated the termination of rubber tree. According to this, the rubber tree died at the age of 166, 149, 107, and 102 days after planting. Chemical fertilizer associated with clay mineral as basal application showed a trend of extending rubber age.