Mohamed Nouri, Taoufik El Rasafi and Abdelmajid Haddioui
In this work three heavy metals: cadmium (as CdSO4), cobalt (as CoCl2) and zinc (as ZnSO4), were used to determine and compare their toxicity towards two subspecies of barley (Hordeum vulgare subsp. vulgare L. and Hordeum vulgare subsp. distichum L.), focusing on seeds germination, seedlings growth, and cytological parameters. The results indicate that the effect of these heavy metals depends on the metal kind, the metal concentrations and the plant subspecies. Generally, in the case of H. vulgare, the heavy metal salts understudy did not influence significantly seed germination and seedling growth parameters. However, these metal salts influence significantly these parameters for H. distichum. The cytological test showed significant decrease (p < 0.05) in the mitotic index among the increase of the heavy metal concentrations when evaluated with the control for H. vulgare and H. distichum. Consequently, H. vulgare seemed to be more tolerant of the increase of the three heavy metals concentrations than H. distichum.
Two field experiments were done at a private farm in Kalabsho and Zayian district, Dakhlia Egypt, throughout 2014/2015 and 2015/2016 seasons, to evaluate the promotive role of chitosan (Chi, 250 and 500 mg/l) and/or sodium metasilicate (Si, 125 and 250 mg/l) foliar application on barley growth, yield, and some physiological attributes in newly reclaimed soil. Application of Si or Chi concentrations showed an improvement in plant growth as: plant height, tiller number per plant, flag leaf area and shoot dry weight; photosynthetic pigments; organic osmolytes; ion percentage, as well as yield and its quality in both growing seasons. Generally, the application of Si gave higher values in most cases than Chi application in the experimental year. It was concluded that application of 125 mg/l sodium metasilicate twice at 50 and 70 days from sowing is advantageous to improving plant growth and productivity under newly reclaimed soils.