Document Type : Research Paper

Authors

1 Ph.D. student, Department of Horticulture, University of Bu-Ali Sina

2 Associate Professor of Department of Horticulture, University of Bu-Ali Sina,, Hamedan

Abstract

In this study, the drought tolerance threshold and relationships between some biochemical and physiological responses of two stone fruit rootstocks, Cadaman and GF677, were investigated. For this purpose, an experiment has been done using factorial trial based on a completely randomized design with three replications. One-year-old rooted cuttings of two rootstocks were exposed to drought stress (-0.1 (control), -0.6, -1.1, -1.6 MPa) by adding different amounts of polyethylene glycol-6000 to Hoagland nutrient solution. Significant increase in electrolyte leakage and decrease in leaf relative water content of Cadaman and GF677 rootstocks occurred at -0.6 and -1.1 MPa, respectively. Concentration of photosynthetic pigments and quantum yield of photosystem II (FV/FM) were less affected by drought stress and decreased significantly in Cadaman and GF677 rootstocks at -1.1 and -1.6 MPa, respectively. Under severe drought stress, photosynthesis, transpiration, intercellular CO2 concentration and stomatal conductance in Cadaman rootstock were more considerably decreased, compared to GF677. Moreover, at drought stress of -1.6 MPa, GF677 did not significantly reduced its photosynthesis, despite a substantial decrease in transpiration; however, the relative decrease in photosynthesis of Cadaman at -1.6 MPa was much greater than the relative decrease in its transpiration and intercellular CO2 concentration, which, in turn, resulted in a decrease in water use efficiency and mesophilic conductance of Cadaman leaves, compared to GF677. It seems that considerable reduction in photosynthesis in Cadaman rootstock, along with stomatal limitations, is largely due to non-stomatal constraints such as loss of cell membrane intact and reduction of chlorophyll, carotenoids and chlorophyll fluorescence

Keywords