Effects of available-water deficiency and silicon concentration in nutrients solution on some physiological, biochemical and growth characteristics of wheat

In order to investigate the effect of silicon concentration in substrtae on some physiological, biochemical and growth characteristics of wheat (Triticum aestivum L. cv. Chamran) under available-water deficiency, this experiment was conducted in Ramin Agricultural and Natural Resources University, Khuzestan, Iran, in 2012. The experiment was arranged as factorial, based on randomized complete blocks design with three replications. Treatments included available-water deficiency stress at three levels (non-stress (control), mild stress (-5 atm osmotic pressure) and severe stress (-10 atm osmotic pressure) by solving 175 and 230 grams of polyethylene glycol 6000 per liter of distilled water). The second factor was different levels of silicon (0, 1, 2 and 3 mM/L) in the form of potassium silicate (K2SiO3). Results showed that the effect of water-deficiency stress increased significantly the proline content (74.4%) and silicon concentration of shoots (69.1%) and reduced the soluble proteins content, stomatal conductance, membrane stability index and shoot and root dry weight by 18.6, 66.6, 24.2 37.8 and 51.9%, respectively, as compared to control treatment. Also, the effect of silicon concentration in the nutrients solution, except root dry weight, was significant on the other traits. Silicon had the greatest impact on shoots’ silicon content and led to a 53% increase in this index. The presence of silicon in non-stress treatment had no significant effect on the traits and its effect was enhanced with an increase in stress intensity. Application of 2 and 3 mM/L of silicon increased shoot dry weight by 18 and 21% in mild stress and by 25 and 31% in severe stress conditions, respectively, as compared to no-silicon treatment, and there was no significant difference between these two values