Effect of Silicon (Si) Application on Phoenix dactylifera L. Growth under Drought Stress Induced by Polyethylene Glycol (PEG) in Vitro

Abstract

This study was carried out to investigate the effects of silicon (Si) 3.6 mM (as calcium silicate) under drought stress induced by polyethylene glycol " PEG " at 15% (MW 8000), in addition to the control treatment on growth and some biochemical consti-tuents of date palm cv. Barhee cultured in vitro. Drought stress (15% PEG) depressed the growth of shoot and decreased protein content and chlorophyll concentration. Addition of 3.6 mM Si could improve the growth of shoot and increase the protein content and leaf chlorophyll concentrations of stressed plants. The inclusion of Si to the PEG containing medium significantly increased the catalase (CAT) and superox-ide dismutase (SOD) activity in regenerated shoot, compared to other treatments. As well as drought stress 15% PEG induced significant accumulation of shoots proline, which were decreased by added silicon. Moreover, the results were also supported by the observation that PEG stress-induced decrease the response percentage of root induction and root lengths was reversed by added silicon. Addition of Si obviously significantly increased the wax content in leaves, response percentage of root induc-tion and root lengths of plantlets under drought stress. The results of this study indi-cate that the application of silicon improved growth attributes, effectively mitigate the adverse effect of drought, and increase tolerance of date palm plants for drought stress during the course of date palm tissue cultures.