Effect of partial root drying on growth and photosynthesis of tomato (Lycopersicon esculentum L.)

Tomato plants were grown in commercial compost with the root system divided equally in two parts (PRD technique). At the end of vegetative and during generative stage of development, half of the root system was exposed to drought, while the remainder of the root system was irrigated. One PRD treatment took c.10 days and during this period the soil water content in the dry root side was reduced to 30%. After this, the treatment was reversed, allowing the previously dry compartment to be well-watered and the well-watered compartment to dry down. In control plants both compartments were watered daily to drip point throughout the experimental period. During experimental period the following measurements were done: plant height, leaf number and area, number of flower trusses, number and diameter of fruit leaf gas exchange (photosynthesis and transpiration), leaf water potential leaf apoplastic pH and water-use efficiency (WUE). Obtained results of plants height and leaf number and area showed that, as a consequence of PRD treatment, the growth of whole plants was reduced, but not fruit, although WUE was increased. These results pointed out that with PRD technique it is possible to reduce irrigation water without significant reduction effect on tomato yield