Responses of tomato plants in mixed-planting with rice during reproductive stage transient flooding

Tomato is a nutritionally rich and economically important crop in the Philippines. Its production is challenging in hot and humid lowland areas due to transient waterlogging during monsoon months. This study investigates the potential of mixed-planting of tomato and rice in attempt to mitigate the adverse effects of transient flooding during reproductive stage. The experiments used split-plot in a randomized complete block design (RCBD) where water treatments (continuous aerobic, flooded-aerobic, and continuous flooding) were the main plots, and plant culture (monoculture and mixed-planting) were subplots. Results showed that tomato and NSIC Rc 216 mixed-planting significantly improved the soil oxygen levels and tomato's physiological responses compared to the monoculture and mixed-planting with NSIC Rc 25. The robust root system of NSIC Rc 216 facilitated a better oxygen diffusion via the radial oxygen loss (ROL) phenomenon, which enhance soil oxygenation and support tomato root respiration under waterlogged conditions. Consequently, the mixed-planting of tomato with NSIC Rc 216 exhibited higher stomatal conductance, prolonged resistance to wilting, and increased root and shoot growth under transient flooding during reproductive stage. Moreover, the study showed a positive correlation between soil oxygen concentration and rice total root length, highlighting the crucial role of rice roots in the maintenance of soil oxygen levels. These findings underscore the importance of selecting rice varieties with strong ROL capabilities for mixed-planting systems aimed at mitigating transient flooding stress in tomato cultivation. Keywords: Tomato, ROL, rice, transient flooding, mixed-planting, reproductive stage