Abstract

Althought safower is a tolerant crop against many environmental stresses, but its yield and performance reduce under stress. The aim of this experiment was to investigate the efect of silicon (Si) application on the possibility of increasing salinity resistance and related mechanisms in safower. A greenhouse experiment was conducted to investigate the efects of Si spraying (0, 1.5 and 2.5 mM) on safower plants grown under salt stress condition (non-saline and 10 dS m−1). Salinity reduced seedling emergence percent and rate, growth parameters and disrupted ion uptake but increased emergence time and specifc leaf weight. Spraying of Si increased plant height, fresh and dry weight, leaf area, relative water content (RWC), potassium, calcium and silicon content, while sodium absorption was decreased. As a result, the K+/Na+ and Ca2+/Na+ ratios were increased. Elevated ion contents and ratios indicate an enhanced selectivity of ion uptake following silicon application and may increase ion discrimination against Na+. Treatment with 2.5 mM Si showed the most positive efect on the measured growth traits. Decrement in leaf area ratio under salinity indicates a more severe efect of salinity on leaf area compared to biomass production. On the other hand, silicon reduced the specifc leaf weight under stress and non-stress conditions, which revalues the positive efects of silicon on leaf area expansion. Improvement of RWC may a reason for the icrease in leaf area and biomass production. Data shows that spraying with Si especialy with 2.5 mM can reduce salinity stress damage to safower and increase biomass production. Keywords Dry weight · Leaf area ratio · Relative water content · Specifc leaf area · Ionic relations