METHOD AND TECHNIQUE OF IRRIGATION IN RELATION TO ROOT SYSTEM CHARACTERISTICS IN FRUIT GROWING.¹

A correct choice of irrigation method and technique presupposes knowledge of the soil volume explored by roots and their density and conformation. Water storage capacity depends on the volume of soil explored, while root density is inversely related to resistances met by water in the root-soil interface.

For four consecutive years, soil volume explored by roots and root system density and conformation were calculated for nectarine trees grafted on two rootstocks and for kiwifruit vines at two different planting densities.

Kiwifruit roots explored a limited soil volume, and differences between the two species increased with tree age. In nectarine, considerable differences emerged according to the rootstock: root system of trees grafted on "Missour" had explored all usable soil by the end of the second year, while those on "Mr.S.2/5" took four years to explore the total volume available.

The results indicate clearly that different methods and techniques of irrigation should be adopted for the two species considered.

Localized irrigation methods are more appropriate for kiwifruit, with frequent applications (daily or every two days in summer) of low volumes of water to the limited volume of soil explored by the roots.