Partial rootzone drying: who is being tricked?
Spreer W., Köller K.
Author Affiliation: Universität Hohenheim, Institute for Agricultural Engineering in the Tropics and Subtropics, Garbenstr. 9, 70593 Stuttgart, Germany.
Landtechnik 60 : 26-27
Abstract : The University of Hohenheim conducted a comparative experiment in Thailand to clarify whether the plant can be tricked by employing partial root zone drying (PRD), or whether the effect is only controlled deficit irrigation (CDI) and placed irrigation is a useless effort. A total of 350 ninety-year old mango trees (cv. Choak Anan) were planted on 0.56 ha experimental plot. Stress symptoms and yield have been controlled in four different irrigation treatments: control with sufficient irrigation (Con), CDI, PRD and a non-irrigated control (0V). During the same application time the PRD plots received approximately half of the irrigation water as the rest of the irrigated plots. To investigate drought stress symptoms in the PRD treatment the stomatal resistance in the course of the day was measured. During the dry season stomatal resistance was higher in all treatments than during the rainy season. At harvest the fruit weight as well as the average number of fruits per tree have been measured. The yield in the PRD treatment did not show significant differences to the completely irrigated control, while the CDI treatment had a much lower yield. Regarding size class distribution CDI and 0V treatment turned out to produce a high amount of fruit which are not useful but for processing (300 g). The absolute number of big fruits is however lower than under full irrigation and PRD. As both treatments PRD and CDI only half of the irrigation water has been applied, water use efficiency in those treatments was high.