Efecto del riego de verano sobre el crecimiento vegetativo en los cultivares de olivo Arbequina y Frantoio

In the last 20 years, olive growing in Uruguay has increased the production area, most of the cases do not have an irrigation system. Currently the main problem in the field is alternative bearing, irrigation being one of the tools to mitigate it. The objective of this work was to evaluate the vegetative growth as a function of the water supply from stone hardening to harvest. Three irrigation treatments (T0: 0% ETc; T50: 50% ETc and T100: 100% ETc) were carried out on 12 Arbequina and 12 Frantoio trees located in INIA LB, Canelones. Eight branches per tree were marked, 4 branches with high flower load and 4 with low flower load. During the growing season, xylem water potential and stomatal conductance were recorded. Every three weeks the number of new nodes generated and the number of fruits per branch were counted. The irrigation treatments were reflected in the evaluated water parameters (water potential and conductance), registering the lowest values for trees under T0 treatment and the highest values for trees under T100. However, the vegetative growth did not show differences from the applied treatments. Between 70 and 75% of the knots generated in the growing season developed prior to the installation of the experiment. The results show a more important effect of fruit load than irrigation treatments, both in Frantoio and Arbequina. The absence of response in our study variables is due to the fact that the range of water potentials in dry land was not within a range that affects the rate of photosynthesis. For future experiments it is recommended, in years of high flowering, to use the flower thinning technique in order to select homogeneous annual shoots.