Applications of Xerophytophysiology in Plant Production - Tomato Fruit Yield and Quality Improved by Restricted Irrigations in Soil-Based Greenhouses

Plant can perceive environment changes and adjust itself internally to get ready to resist the coming adverse conditions. In the present research, drip infiltration, a kind of deficit irrigation, was imposed to tomato plants. This deficit irrigation was perceived by the tomato plants as a false stimulus of drought and made the plants stronger by internal physiological adaptation, such as osmotic adjustment and symplastic water compartmenting. Tomato plants under infiltration irrigation showed a higher osmotic concentration or lower osmotic potential in symplasm at fully turgid status and a consequent higher leaf turgor potential. Leaf symplastic water fraction was larger or apoplastic water fraction was smaller in tomato leaves under infiltration irrigation. Both osmotic potential and relative water content at the point of incipient plasmolysis were lower in tomato leaves under infiltration irrigation, suggesting a higher resistance to water stress. The higher leaf turgor potential and the larger symplastic water fraction might have supported the higher leaf photosynthesis in the treated plants. Soil microbial activities were also improved by infiltration irrigation. In conclusion, horizontal infiltration irrigation can improve plant physiology and consequently increase tomato fruit yield. The higher physiological activities might be resulted from xerophytophysiological responses under unwet or modest dry conditions.