Regulated deficit irrigation (RDI) and partial root drying (PRD): The effects on tomato growth and functional fruit anatomy

Abstract

The experiment was carried out to study the theoretical BACKGROUND: of the effects of new deficit irrigation methods (regulated deficit irrigation -RDI and partial rootzone drying - PRD) on tomato plant and fruit growth. The RDI treatment was 50% of water given to fully irrigated (FI) plants and the PRD treatment was 50% of water of FI plants applied to one half of the root system while the other half dried down, with irrigation shifted when soil water content of the dry side decreased to ca. 20%. Plant and fruit growth parameters were measured as well as functional anatomy parameters (xy-lem and phloem areas in fruit pedicels). RDI significantly reduced plant and fruit growth, though PRD reduced shoot growth while having no significant effect on fruit growth. Anatomy data showed that PRD treatment increased phloem area and reduced xylem area in earlier stages of fruit development, although RDI reduced xylem area at the abscission zone in all phases of fruit development. This could lead to hydraulic and chemical isolation of fruits. Greater hydraulic isolation of PRD fruits from the rest of plant could be theoretical explanation why PRD treatment did not significantly influenced tomato fruit growth and yield.