Silicon alleviates salt stress in pistachio plants

Abstract

In this work, the effects of silicon (Si) supplementation were studied in pistachio (Pistacia vera<br />L. cv Ahmadaghaii) plants exposed to high salinity stress. Plants were grown in pots under<br />control and salt (EC=15 dS m-1) conditions without or with Si treatment (0.35 g Na2SiO3 Kg-1<br />soil) under field conditions. Salt stress reduced the plants' growth significantly in both –Si and<br />+Si plants; however, Si-supplied plants had a higher root and shoot dry weight as compared to<br />those without Si supply under salinity conditions. Salt stress caused a significant reduction of<br />leaf photochemical activities; however, Si application ameliorated these effects. The reduction<br />of the net CO2 assimilation rate under salinity stress was alleviated by Si application,<br />accompanied by an increase in water-use-efficiency. The concentration of Na in the leaves and<br />roots was significantly reduced by Si, while root K and leaf Ca concentrations were higher in<br />Si-treated plants under salt stress compared with –Si ones. The activity of antioxidative<br />enzymes increased under salt stress and Si application caused a further increase, being<br />significant for superoxide dismutase (SOD). Salt stress induced membrane damage, as was<br />indicated by a higher malondialdehyde (MDA) concentration. In Si-supplemented plants,<br />however, the MDA amount did not increase under salt stress. The results indicated that the Simediated<br />alleviation of salt stress in pistachio plants is related to higher photosynthesis and<br />water-use efficiency, a reduction of Na uptake and transport, and the stimulation of the plant's<br />antioxidative defence capacity.<br />