Appropriate stimulant application to determine latex physiology character and production of clone RRIM 921 in Regency of Deli Serdang

Physiological characteristics of rubber trees are closely related to the ability to form latex. Sucrose, inorganic phosphate, and thiol levels in latex are physiological characters. The purpose of this study was to determine the correlation between physiological characters and latex production of clone RRIM 921 and proper stimulant application without disturbing the health of rubber trees. This research was conducted at PT. Perkebunan Nusantara III (Persero), Sei Putih Farm, and Physiology Laboratory of Sungei Putih Research Institute in 2018. The clones tested in this study were 17 years old of clone RRIM 921. This study uses correlation statistical analysis and regression test. Correlation analysis show that Pi level has negative significant correlation with Thiol latex, where high level of Pi will be followed by low level of thiol and vice versa. Latex production of clone RRIM 921 in May, June and July were not affected by latex physiology. The right stimulant application after leaf fall for RRIM 921 is in May.