Effects of Water Supply and Intercropping on Survival Rate and Growth of Para Rubber (Hevea Brasiliensis)
Para rubber is one of the most important economic crops in the Northeast of Thailand. However, hot and dry conditions in this area lead to low survival rate and growth of young rubber trees. In addition, under intercropping system, the competition between rubber trees and intercrops for limited resources may cause more water deficit and adverse effects to rubber trees. The objective of this study was to investigate the effects of water supply, intercropping and their interaction on survival rate and growth of para rubber. The experimental design was split plot in Randomized Complete Block Design (RCBD) with 3 replications. The main plots included 3 methods of irrigation (drip irrigation, mini sprinkler and no irrigation). The sub plots consisted of 2 methods of intercropping (cassava intercropping and no intercropping). The results showed low survival rate and growth of rubber tree in no irrigation treatment. Both survival rate and growth of rubber trees increased significantly by both irrigation methods. There was an interaction between irrigation and intercropping on growth of rubber trees. Under non-irrigated conditions, cassava intercropping significantly reduced growth of rubber trees compared to no intercropping, but under irrigated conditions, cassava intercropping had little effect on rubber tree growth. The growth reduction under intercropping without irrigation was the result of the competition for limited soil water between cassava and rubber tree. Water application to fulfill the requirement of both crops would relieve the competition effect.
Keywords - Para Rubber, Irrigation, Intercropping, Drip Irrigation, Mini Sprinkler