Effects of different boron concentration on the growth and physiological characteristics of two olive cultivars

This study investigated the effect of different boron concentrations on growth and physiological characteristics of olive plants. The absorption of some macronutrients and distribution of boron were also examined. This research was carried out in a completely randomized design with factorial arrangements including six boron levels (0.2, 10, 20, 30, 40 and 50 mg L^?1) and two cultivars (Amygdalolia and Konservolia), with four replications for each treatment. Two-year old seedlings were treated with Hoagland nutrient solution containing different boron (B) concentration for 4 months. Chlorophyll fluorescence, fresh and dry weight of leaves, stems and roots as well as absorption of macronutrients decreased in both cultivars as the boron level were increased. Diagnostic symptoms of boron toxicity appeared 45 and 75 days after planting for Amygdaloila and Konservolia at 30, 40 and 50 mg L^?1; and 40 and 50 mg L^?1 of boron, respectively. Our results showed that at a higher level of B, the Konservolia cultivar maintained more B concentration in its root than Amygdalolia cultivar; however, B content in young leaves of Amygdalolia was higher than Konservolia. It seems that Konservolia cultivar could accumulate B in its roots and prevents its translocation to the leaves through an internal tolerance mechanism; therefore, Konservolia shows greater tolerance to high concentrations of boron compared to Amygdalolia.