Nut crops are in limited supply within the European Communities (EC) but there is a need to reduce the costs of European nut production if it is to compete with other nut production areas in the world. Irrigation is one of the agricultural practices that has most effect on production but water is a limited resource in European nut producing areas and is costly. Work is being done to reduce production costs by inceasing the efficiency of water utilization by nut trees and particularly to find an appropriate controlled deficit irrigation (CDI) schedule that will give greater yields using reduced amounts of water.
On almond, the effect of drought sensitivity is being investigated by withholding irrigation water at the most important periods of vegetative growth, fruit growth, kernel growth and after harvest. Water balance experiments are being conducted on a commercial almond orchard of 1 hectare, with 4 different irrigation treatments.
On hazelnut, experiments have been initiated on drought sensitivity, similar to those described for almond. Also under investigation are the effects of localized irrigation, which introduces a differentiated water supply to different parts of the root system, with effects on the physiological and hormonal behaviour of the whole plant. Pot experiments are being conducted on the influence of water levels on assimilation and water use efficiency. In another orchard trial on hazelnut, trickle irrigation is used to compare 3 different levels of irrigation with dry cultivation.
On walnut, experiments have been set up to characterize the daily course of water state of trees subjected to different water regimes. Measurements are being made of sap flow in the trunk and changes in stem diameter.
On pistachio, experiments have been set up using drip irrigation to compensate for various levels of potential evapotranspiration. Measurements will be made of vegetative, fruit and seed growth.
Modern European nut production requires to reduce costs in order to be competitive with other nut production areas in the world. Since tree nuts are not in surplus within the EC, a way to reduce "cost/unit of product" is to increase yields and reduce or optimize input utilization.
Irrigation is one of the agricultural practices that has more effect on production, but water is normally a very limited resource in the European nut producing areas. Therefore, the project will be based on experiments to reduce production costs by increasing efficiency on water utilization in nut trees. This requires : to determine water consumption of these species (Action I) and their physiological responses to water stress situations (Action II) in order to analyze, understand and modify the treatments, if necessary, of controlled deficit irrigation (CDI) field-trial strategies (Action III), which is the main goal of this project. To improve CDI strategies, new methodologies (Action IV) of plant-based measurements will be tested.
The expected benefits are :
A. to improve the competitiveness of the EC nut production by reducing the costs due to improved water utilization efficiency;
B. to contribute to the valorization of some natural resources (soil, water) under marginal conditions. In fact, some of the nut tree species have a good capacity to yield under dry conditions, with a very good productive response to limited amounts of irrigation water supply;
C. to improve alternatives for the surplus crops, since nut crops can substitute other species into the Mediterranean region, under dry or irrigation conditions (almond or pistachio could be alternatives to the olive tree or grapes; walnut or hazelnut can be alternatives to some surplus fresh fruits, ...);
D. since water availability is a very important constraint in large areas of the EC, the optimization of reduced amounts of water should have important social and economic benefits in these regions.
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38206 La Laguna