In Myanmar, natural rubber (Hevea brasiliensis) is mainly grown in the southern part of the country, where the rainfall is too high leading to suspension of tapping in the rainy season and intensive tapping after the rainy season. Rubber farmers face problems of uneven distribution of tapping days, low tapper productivity, high tapping cost, and shorter economical lifespan of the trees. Hence, a study was carried out to address the problems by conducting an on-farm experiment to assess performances of low frequency rubber tapping system (LFRTS) with rainguard in the area. Five treatments: (T 1 ) S/2 d2 (no tapping in the rainy season); (T 2 ) S/2 2d3 (no tapping in the rainy season); (T 3 ) S/2 (RG) d2 (tapping with rainguard in the rainy season); (T 4 ) S/2 d3 ET2.5% Pa (1) 3/y (m) (tapping without rainguard in the rainy season); (T 5 ) S/2 (RG) d3 ET2.5% Pa (1) 3/y (m) (tapping with rainguard in the rainy season) were evaluated. The cumulative yield in kilogram per tree of T 5 during the study period was comparable to that of T 1 , while its daily yield in gram per tapping per tree was 23% and 30% higher than that of T 1 and T 2 , respectively. Bark consumption of T 5 was 16% and 39% lower than that of T 1 and T 2, respectively. T 5 needed only 67% of tapper requirement by d2 frequency tapping. Tapping costs of T 5 were 17% lower than those of conventional tapping system, T 1. The study suggested that LFRTS with rainguard could be implemented to address the problems of the farmers in the area.Keywords: bark consumption; low frequency rubber tapping system; rainguard; tapping cost; tapper productivity; tapper requirement. Abbreviations: 2d3_ two tappings in three days; BO-2_ virgin bark at second basal panel; d2_ alternate tapping; d3_third daily tapping; ET_ethephon stimulation; LFRTS_ low frequency rubber tapping system; Pa_ panel application; RG_rainguard; S/2_ half spiral cut (length of tapping cut)

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The replanting practice of rubber monocropping in Southern Thailand has depleted soil fertility. Most rubber planted areas in the region were under intensive chemical fertilization resulting in less soil organic matters and root proliferation. With the instability of rubber prices, some rubber farmers converted from monocropping into intercropping. Integrated fertilization in which mixed organic-inorganic fertilizers are combined with organic soil amendments could be considered in a rubber-based intercropping system to increase land productivity with cost-saving fertilization by rehabilitating soil properties. A study was conducted at a rubber-salacca intercropping farm comprised of 14-year-old mature rubber trees associated with eight-year-old salacca palms to identify the consequences of the integrated fertilization combined with two organic soil amendments: humic acid (HSA); chitosan (CSA). Changes in soil organic matter (SOM), leaf area index (LAI), fine root traits, tree physiological status, and crop productions under the two integrated fertilization were compared against the controlled application of conventional chemical fertilizer. The CSA application increased the SOM in the topsoil layer by 80%. In the 21 – 40 cm soil depth, the rubber roots treated with HSA and the salacca palm roots treated with CSA showed greater fine root length density (FRLD). Under CSA, the physiological status of the rubber trees showed less stress. The treatments of HSA and CSA showed 145% and 72%, respectively, higher in total production of salacca palm than that of the chemical fertilization. Improvements in the soil fertility, the root’s function, the crops’ yields, and the tree physiological status were consequences as complementarity in the system under the integrated fertilizations.

Hevea rubber farm is viable for agroforestry systems since its canopy lessens extreme weather conditions and contributes to the adaptation of shade-tolerant plants. However, some limitations in the availability of soil water and shades vary with the age of rubber trees and affect the understorey plants’ acclimatization. Tropical palms are potentially associated plants for the rubber-based agroforestry systems because they are rainforest species adaptable to understorey environments. Two rubber farms, ages 12 and 25 years, intercropped with tropical palms were selected to investigate the acclimatization of the palms to the seasonal abiotic variations in the mature rubber farms. The studied palm species were Chrysalidocarpus lutescens and Rhapis excelsa in the 12-year-old rubber farm and Livistona speciosa and Licuala spinosa in the 25-year-old rubber farm, respectively. Leaf area, stomatal conductance, photosynthesis pigments, and leaf nitrogen content were identified as the palms’ morpho-physiological traits. The 12-year-old rubber farm had a marked soil water deficit in all soil depths at the beginning of the rainy season, reaching around 200 kPa at the 80 cm soil depth, while the 25-year-old rubber farm received greater light transmissions, ranging between 37 and 46% in the late dry season. All palms adjusted leaf area to balance the photosynthetic capacity. The Rhapis palm had greater acclimatization with significant responses of stomatal conductance. Other than the Licuala palm, all palms exhibited the allocation of chlorophyll pigments and nitrogen content significantly in their leaves in response to the different intensities of abiotic stresses in the understorey of the rubber farms.