Evaluation of kiwifruit performance under stress caused by regulated deficit irrigation (RDI) and partial root zone drying (PRD)

Awareness of the impact of water deficit stress on kiwifruit quantity and quality is essential for irrigation management and production. To evaluate the performance of kiwifruit under water deficit stress, this study was conducted in Sari Fajr Company in a completely randomized design with three treatments and three replications in 2011. Treatments included full irrigation (FI), partial root zone drying (irrigation alternating between two sides of the root) (PRD) and regulated deficit irrigation (RDI) at 75% level. The root zone moisture was measured by TDR moisture sensors. The amount of irrigation water was determined from difference between soil moisture within the root zone and moisture at field capacity point. Evaluating the fruit performance was conducted by measuring the fruits quantitative and qualitative traits including fruit volume, size in different directions, fresh and dry weight, moisture, titratable acidity (TA) and total soluble solids (TSS). Depth of irrigation water for FI applied during plant growth and deficit irrigation treatments were 235.60 and 137.60 mm respectively. The amount of water-saving of deficit irrigation treatments compared to FI during vegetative and applying deficit irrigation treatments were 14.60% and 25% respectively. Comparison between treatments according to Duncan's test showed that effect of treatments on fresh and dry weight, volume, y and z dimensions was significant, but not significant for characters x, TSS, moisture and TA. The highest amounts of TSS were at RDI. The results showed that applying deficit irrigation treatments caused to improve the quality of fruit and saving water at water deficit condition.