84 SALINITY AND WATER MANAGEMENT IN AVOCADO

What is distinctive about the avocado water and salinity relations? It may not be much ex-cept for the fact that avocado is the most salinity sensitive crop among fruit trees (especially chloride salinity) yet its response to water shortage is mild and it exhibits great variability in results. Indeed, the class A pan factor (Kp) ranges from 0.42 in June to 0.61 in October (Shalhevet et al., 1981). Similar results were obtained by Steinhardt et al,1993 were the mean Kp for the irrigation season was 0.5. For citrus, the mean Kp factor was 0.5 as well (Shalhevet et al., 1981). Water requirement of avocado The following production function curve (Fig. 1) was constructed using some mathematical manipulations (Steinhardt et al., 1991) and it looks good. The data points, on which it is based, are presented in Figures 2 and 3. The spread of the data is quite large resulting from year to year (weather), site to site (soil and climate), rootstock and variety, and cultural practices variations