The effect of coarse and nano particles of silica on increasing drought resistancein seedlings of gall oak (Quercus infectoria Oliv.)

Silicon plays an important role in increasing plant resistance to drought-stress. In this study, the effect of silicon on drought-stress in seedlings of gall oak (Quercus infectoria Oliv.) was investigated. The seedlings were transferred from forest nursery of Marivan Natural Resources Office to Urmia University and were subject to an experiment as a factorial design based on complete randomized blocks in three replications. Seedlings were irrigated by two types of silicon (coarse and nanoparticles) in different concentrations (0, 50, 100 and 150 mg L-1) pre-treatment during a 30-day period based on field capacity. Then, drought stress was imposed on three levels, which consisted of control (based on field capacity), moderate stress (based on 50% field capacity) and severe stress (water withholding) for 21 days. The results showed significant and main effects of silicon type on the amount of silica, drought stress on proline and silicon concentration on proline and silica. However, the interaction effects of drought stress with silicon type and drought stress with silicon concentration were significant only on the proline. None of independent and interaction effects of the fixed factors on growth parameters and the amount of carbohydrate were significant. Generally, silicone application had only a significant effect on severe drought stress in reducing proline content, but there no difference was observed between coarse and nanoparticles. The absorption of silica was obviously higher in the nanoparticle type. Finally, the application of silicon at a concentration of 50 mg L-1 in severe drought stress conditions was concluded to enable increasing the tolerance of Q. infectoria seedlings against drought stress.