Fruit yield response of a mandarin (Citrus reticulata ) orchard to deficit irrigation, which was imposed either through conventional deficit irrigation (DI) or a newly evolving irrigation technique, called partial root drying (PRD), was investigated. | Turk J Agric For 31 (2007) 1-10 © TÜB‹TAK Mandarin Yield Response to Partial Root Drying and Conventional Deficit Irrigation Cevat KIRDA*, Fatih TOPALO⁄LU, Sevilay TOPÇU, Harun KAMAN Çukurova University, Faculty of Agriculture, 01330 Adana - TURKEY Received: Abstract: Fruit yield response of a mandarin (Citrus reticulata cv. Marisol) orchard to deficit irrigation, which was imposed either through conventional deficit irrigation (DI) or a newly evolving irrigation technique, called partial root drying (PRD), was investigated. The PRD practice simply requires wetting of one half of the rooting zone and leaving the other half dry, thereby utilising reduced amount of irrigation water applied. The wetted and dry sides are interchanged in the subsequent irrigations. Six irrigation treatments were tested: (1) TR, traditional farmers’ method of irrigation where irrigation management was left to the full control of a grower; (2) FULL irrigation where the full amount of irrigation water (60% Class-A pan evaporation) was applied to the both halves of tree-root zone; (3) 1PRD30 and (4) 1PRD50, 30 and 50% reduced amount of irrigation water, compared respectively to FULL irrigation, was applied alternately on each half side of the tree rows, and the irrigated side was changed every irrigation; (5) 2PRD50, 50% reduced amount of irrigation water was applied on each half side of the tree rows, and the irrigated side was changed every other irrigation; (6) DI50, conventional deficit irrigation where 50% reduced amount of irrigation water, compared to FULL irrigation, was applied to the both halves of the tree-root zone, similar to FULL irrigation. A randomised complete block experiment design with 6 replicates, 4 trees each, was used. The orchard had 6-year-old trees, planted in 5-m rows of a parallelogram arrangement. A drip irrigation system with 2 laterals, laid along the tree rows with trees located m midway -1 between the laterals, was used. The drippers with
