Sap flow in mango and guava seedlings irrigated with treated waste water in Jericho City, Palestine
We conducted a small-scale experiment to establish a technique for using treated waste water for the cultivation of mango in Jericho, Palestine. Mango and guava seedlings (n=16 each) were transplanted in December 2014 and irrigated with treated waste water using a drip irrigation system that was automatically controlled by tensiometers. Sap flow in the seedlings was then measured using the heat ratio method from July 2015 until the present. The diurnal curve of sap flow in the mango stems indicated that the plots were experiencing low levels of water stress and this was verified through a water stress experiment. However, sap flow remained at a constant level during the hot summer of 2015 despite difficulties with water transport, indicating that the use of treated waste water may be viable for the outdoor cultivation of tropical fruits. Some data were missing from the long-term dataset due to power outages and the mango seedlings were damaged by an unexpected chilling stress during the following winter. Therefore, to supplement these missing data and convert them into transpiration rates, we conducted calibration experiments using similarly sized potted mango plants in a greenhouse and measured water uptake using heat pulse velocity. The calibration results showed that it is important to consider the location of the sensing point in the stem as seedlings grow rapidly. From these experiments, we estimated that the maximum daily transpiration rate was 1.2 L. We also assessed the automatic irrigation system by measuring sap flow in potted mango plant supplied with saline water and used the relatively high heat pulse velocity that was measured to establish criteria for three levels of irrigation. Overall, we found that this automated irrigation system works well and will be valuable for conducting field tests in the future.
Takeuchi, S., Fujimaki, H., Aoki, H., Maaba, H., Alary, R. and Bsharat, M. (2018). Sap flow in mango and guava seedlings irrigated with treated waste water in Jericho City, Palestine. Acta Hortic. 1222, 121-126
sap flow, treated waste water, calibration, mango, guava