Water and salt transport, water uptake, and leaf water potentials during regular and suspended high frequency irrigation of citrus

Abstract

High frequency irrigation of citrus was interrupted for up to 2 months to study the dynamics of salt and water transport in soil, water uptake distributions and leaf water potentials. Irrigation water was applied to less than half the surface area per tree. Water content profiles and chloride distributions indicated that of the water uptake below the irrigated area, about 80% took place above 0.60-m depth, and that considerable water was taken up from outside the irrigated area. The water for the latter was supplied by lateral flow, as evidenced by the hydraulic gradients, the relative extent of the lateral flow in summer and winter, and the fact that at 0.90-m depth water contents were uniform. In summer, the citrus showed signs of stress after about 4 weeks of suspended irrigation. At that time leaf water potentials did not recover any longer during the night. This study indicates that high frequency irrigation of citrus is not too vulnerable to temporary system breakdown and that deficit-irrigation could be practiced.