EFFECT OF SOIL APPLICATIONS OF KCL PLUS CACL2 ON TABLE GRAPES

Abstract

Plants have developed physiological mechanisms to adapt to high soil salinity, such as stomatal closure and osmoregulation. The latter allows maintenance of water flux because of an increased internal osmotic pressure. We carried out an experiment in a commercial 'Thompson Seedless' table grape vineyard in central Chile (34°20' S, 71°17' W) where concentrated solutions of CaCl 2 and KCl were applied to the soil regularly during December and January of the 2005/06 and 2006/07 growing seasons. Soil analyses showed that, where the salt solutions were applied, chloride (Cl) levels and electrical conductivity (EC) were higher, but K and Ca levels were similar to the control. Foliar and fruit analyses showed that Cl concentrations were higher in both seasons in leaves and fruits from vines exposed to the applied salts. Shoot, bunch and berry weight did not differ between treatments. Berry firmness at harvest and 30 days postharvest was higher in the salt treatment while berry dry matter percentage was lower. Cell area was measured in histological sections of berries from both treatments, and larger cells were found in fruit from the salt treatment. These results suggest that grapes have osmoregulation mechanisms that respond to high amounts of Cl in soil.