Growth and Osmotic Adjustment in Two Almond Rootstocks under Water Stress Conditions

A greenhouse experiment was conducted in 2010 to evaluate the response of seedlings and cuttings of GF677 hybrid (Prunus persica and P amygdalus) rootstock and bitter almond seedlings (P. dulcis) to water stress. After determination of field capacity (FC) of the soil used for potting, irrigation treatments were imposed by daily irrigation to FC and 2, 4 or 8 day intervals for 96 days. Delaying irrigation had no significant effect on shoot growth and diameter, but decreased leaf production. Root number and length and root to shoot ratio in GF677 seedlings and cuttings increased with increasing frequency of irrigation. In GF677 seedlings and cuttings, delaying irrigation from 0 to 8 days increased leaf sugar, potassium and proline concentrations significantly, and potassium had a significant role in reducing osmotic potential. GF677 seedlings and cuttings had a greater ability to withstand water stress than bitter almond seedlings. It was concluded that conventional bitter almond rootstocks currently considered most tolerant to drought can be replaced by cuttings of GF677 rootstock.