Pistachio rootstocks influence scion growth and ion relations under salinity and boron stress

Performance of 'Kerman' pistachio (Pistacia vera L.) trees on three rootstocks (P. atlantica Desf.,P. integerrima Stewart and IUCB-1', a A atlantica X A integerrima hybrid) was evaluated with 2-year-old trees grown in sand-tank lysimeters under combined SO42- and Cl- salinity and boron (B) stress for 6 months. Four salinity treatments were imposed by irrigating the plants with water at electrical conductivity (ECiw) of 3.5, 8.7,12, or 16 dS.m(-1) each containing B at 10 mg.L-1. Growth of 'Kerman' was evaluated based on increase in total leaf area, increase in trunk diameter, and total above-ground biomass production. All growth parameters decreased as salinity increased, but were not significant until ECiw exceeded 12 dS.m(-1). However, growth of 'Kerman' on A atlantica and 'UCB-1' was considerably better than on P. integerrima at 16 dS.m(-1). The onset and severity of foliar injury differed among scions and treatments and was attributed primarily to B toxicity, rather than the effects of salinity. Concentrations of B in injured leaf tissue ranged from 1000 to 2500 mg.kg(-1). Leaf injury decreased with increasing salinity, although leaf B was not significantly reduced suggesting an internal synergistic interaction between B and other mineral nutrients. However for A vera on A integerrima, the highest level of salinity produced the greatest injury, possibly as a combination of B plus Cl- and/or Na+ toxicity. Leaf transpiration, stomatal conductance, and chlorophyll concentration of A vera, determined by steady-state porometry, were also reduced to a greater degree by combined salinity and B when budded on A integerrima than on the other two rootstocks.