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Project Profile

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Northern R&D

Response of fruit trees to severe water stress and different crop loads

Background: Tel Hai College

Water shortage in the Northern part of Israel is more pronounced relative to other regions as the availability of reclaimed water is limited due to the low population density and because no such water will be imported to the Sea of Galilee basin.

Deficit irrigation affects the current season production and if it is severe the recovery process may require a few seasons. In order to optimize irrigation regimes under water shortage, the effect of different deficit irrigation levels should be examined and the development of thresholds of water stress indicators for irrigation scheduling.  It should include a better understanding of how water stress affects stomatal aperture, photosynthesis and the accumulation of carbohydrate reserves - the deeper the understanding the more generalized the results are and the wider and faster the implementation of the research outcomes.

In order to conduct the studies properly one needs to use portable gas exchange system that allows the measurement of stomatal conductance and photosynthesis in the field as well as responses to temperature and CO2 concentrations. In addition water stress indicators (pressure chamber, dendrometers, leaf thickness and tensiometers) will have to be purchased.

Program: It is intended to use the new portable gas exchange system and the water stress indicators in experiments in almond, olive, banana, dates, apple, and avocado. All the experiments are conducted in commercial plots.

Justification: Currently, only minimal measurements of gas exchange are taken because we have to borrow the gas exchange system – the new gas exchange system to be purchased will improve dramatically the volume of measurements and the depth of research and will clearly improve the outcomes of the many irrigation studies that are performed.



The main objectives of the project are:

To provide growers with irrigation and thinning protocols to minimize water deficit damage and to increase water use efficiency in fruit trees and specifically:

To better understand the combined effect of irrigation level and crop load on crop yield and fruit size and the long term productivity by studying the role of water stress and crop load in gas exchange and the accumulation of carbohydrate reserves.

Dr. David Cohen