Rootstock and nitrate involvement in 'Ettinger' avocado response to chloride stress

The damage caused by excess chloride in 'Ettinger' avocado plants grown on the Mexican rootstock, Schmidt appeared mainly in the leaves and shoots, whereas the main toxic influence of chloride on the West Indian rootstock, Zriphin 99 rootstock appeared in the root system which showed a strong peroxidative activity. The dry weight of the roots of Zriphin 99 was also reduced and shoot/root ratio was increased, whereas the roots of Schmidt rootstock were much less affected. An increased level of chloride ion was detected in the leaves of 'Ettinger' /Schmidt compared with plants on Zriphin 99. The level of nitrate ion was higher in leaves of 'Ettinger'/Zriphin 99 than in those of plants grown on Schmidt. The activity of nitrate reductase was correlated with the damage caused by excess chloride level to 'Ettinger' cultivar grown on either rootstock. The study demonstrates and evaluates the parts played by rootstock and nitrate in avocado response to chloride stress.