Evaluation of low frequency tapping systems with stimulation on hevea in traditional area Cambodia

In Cambodia, the common tapping system which was widely adopted by smallholders and agro-industry plantations was S/2 d3 for downward tapping and S/4 d3 for upward tapping. However, under the decline of rubber price and increasing labor shortage, the application of low frequency tapping systems (LFT) may be a choice to solve these problems. Hence, different low frequency tapping systems were tested in traditional area of Cambodia. An experiment was established using seven-year old rubber trees of RRIM 600 clone at the Cambodian Rubber Research Station located in Tbong Khmum province. The experimental design was Randomized Complete Block Design with four treatments: T0: S/2 d37d/7 ET 2.5% 4/y, T1: S/2 d4 7d/7 ET 2.5% 5/y, T2: S/2 d5 7d/7 ET 3.3% 6/y and T3: S/2 d6 7d/7 ET 3.3 % 10/y comprising three replications (12 elementary plots). There were 120 trees per treatment in each elementary plot. After 3 years of tapping, LFT system S/2 d6 with Ethephon application (T3) provided the highest dry rubber yield per tree per tapping (g/t/t) but the lowest yield in gram per tree (g/t) and kilogram per hectare (kg/ha). As compared to d3, LFT systems (d4, d5 and d6) caused dry rubber yield loss in kg/ha by respectively 3, 9 and 11% but resulted in increased labor productivity (g/t/t) by respectively 11, 28 and 48%. Therefore, the increase in labor productivity (g/t/t) was higher than the loss in land productivity (kg/ha). Girth increment was not significantly different between treatments. Sucrose and reduced thiol contents of all treatments were not significantly different but inorganic phosphorus content was significantly different depending on the tapping system. Tapping panel dryness was similar for all treatments after three years of tapping