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The aim of the investigation was to study the effect of colloidal solution of Cu2+ and Zn2+ nanoparticles on the pro/antioxidant balance, the content of photosynthetic pigments (chlorophylls a, b and carotenoids), the chlorophyll a/b ratio and the morphometric parameters (relative leaf water content, leaf area) of winter wheat Triticum aestivum L. varieties Acveduc (steppe ecotype, resistant to drought) and Stolichna (forest-steppe ecotype, sensitive to drought) under conditions of simulated drought. The drought was created by stopping of watering on the 8th day after emergence and maintaining the soil moisture at 30 % of the total moisture capacity for 3 days. Pre-sowing treatment of seeds with Cu2+ and Zn2+ nanoparticles was carried out by soaking of seeds in experimental solution (1 part of the mother colloid solution: 100 parts of water) for 4 hours. The control variant was soaked in distilled water. Then the seeds were washed and planted in a sand culture. The varietal specificity of the influence of a colloidal solution of metal nanoparticles on seedlings of the Acveduc and Stolichna varieties was revealed. Presowing treatment of seeds with Cu2+ and Zn2+ nanoparticles led to significant changes in the pro/antioxidant balance in leaves of seedlings, reducing the level of accumulation of TBARS, increasing the activity of key antioxidant enzymes (superoxide dismutase and catalase), stabilizing the content of photosynthetic pigments, increasing the relative water content in leaves and leaf area under simulated drought conditions. In general, under drought conditions, presowing of seed treatment with a colloidal solution of nanoparticles had a positive effect on the proantioxidant balance of plants and the morphometric parameters of leaves to a greater extent in seedlings of the steppe ecotype variety (Acveduc) and less in seedlings of the forest-steppe ecotype variety (Stolichna). [ABSTRACT FROM AUTHOR]

It is established that under natural drought conditions starch was accumulated in the central part of chloroplasts of mesophyll cells and chloroplasts were localized on the periphery of cells at plasmalemma. After treatment wheat plants by nitric oxide donor the decreasing of starch deposits number and close contacts between chloroplasts were indicated, elongated nucleus was localized in the centre of cells. After treatment wheat plant by mercury chloride chloroplasts in the cells lost their oval shape and contacts, increased eventually deposition of starch, indicating the acceleration of aging tissues. Thus, nitric oxide in drought conditions reduced the destructive effect of drought on mesophyll cells, and mercury chloride caused deformation of the membrane cell. [ABSTRACT FROM AUTHOR]