THE INFLUENCE OF REGULATED DEFICIT IRRIGATION (RDI) ON THE GROWTH AND PRODUCTIVITY OF PEACH TREES

The amount of water was calculated as follows:

• treatment 1: from the begining of irrigation until the shoots reached about 80% of their total estimated length, corresponding to about 25% of full fruit size, 12.5% of ETP was distributed: the total ETP (100%) was reached at the end of harvest. The amount of irrigation applied for the remaining period was again 12.5% of ETP;
• treatment 2: during the first and last period the coefficient used was double compared to treatment 1, while during the intermediate period, prior to harvest, the irrigation volumes were equal to the evaporate (100%);
• treatment 3: the coefficients used were the ones which gave the best results in previous trials with the same cultivar in the same field. This corresponds, for the entire irrigation period, until fruit set (A) to 66% of evaporation multiplied by 50%. These values were increased up to 100% for the last three weeks before harvest. After harvest the coefficient was reduced to the previous level (50%).

No significant differences appeared between treatment 1 and 3 on the yield per tree during the different years. The average fruit weight was pratically the same in all the three treatments.

On the contrary, pruning wood weight and trunk cross-sectional area, resulted proportional to the water used (higher in treatment 3 and lower in treatment 1). However the efficiency production index shows that no differences were found between treatments 1 and 3.

With the R D I method it is possible to save almost one third of the water amount (35.5%) under the conditions of our trial.

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