Sustainable Rubber Production Intercrop with Mixed Fruits to Improve Physiological Factors, Productivity, and Income

This study investigated the impact of various rubber intercropping models on productivity, income, and physiological factors, compared to rubber monocropping in Tamod subdistrict, Phatthalung province, Thailand. Three intercropping models from rubber smallholder farms with mature Hevea trees were evaluated: rubber with timber trees (RT), rubber with timber and fruit trees (RTF), and rubber with timber, fruit, and shrub trees (RTFS). The rubber monoculture served as the control treatment. Data was collected from May 2021 to April 2022. Results revealed that intercropping had an 11.3% lower Tapping Panel Dryness incidence than monocropping (88.7%). The RTFS model had the highest latex yield at 1,866.31 kg/ha/year and dry rubber content at 40.11%, outperforming the other models. In the RTF model, fruit yields were 809, 92, 458, and 61 kg/ha/year for Durio zibethinus L., Lansium domesticum, Garcinia mangostana, and Nephelium lappaceum L. The RTFS model had a Salacca zalaca fruit yield of 1,220 kg/ha/year. Environmentally, the RTFS model had the lowest average temperature (30.5°C), highest humidity (68.8%), and lowest light intensity (2,955 lux) compared to the other models. Soil moisture tension was also least negative in RTFS at -5.7 kPa and -5.3 kPa at 30cm and 50cm depths. Economically, the RTF model had the highest net profit at 4,892 USD/ha/year with a benefit-cost ratio of 2.75 and a return on investment of 176%. Sensitivity analysis showed RTF maintained the highest profits even with ±10% changes in revenue and costs. Rubber intercropping, particularly the RTFS model, improved productivity, income, and environmental conditions compared to monocropping.