Effect of seed germination and functional activity of pectin-silver nanocomposites against the barley net and spot blotches in a model experiment
The pectin-silver (Ag) nanocomposites were obtained in a mass ratio of 10:1 or 25:1 by silver nitrate chemical reduction by Citrus and Classic pectins with molecular weights of 141 and 89 kDa and the degree of etherification of 80 and 38%, respectively. The barley seed germination, growth parameters of 7th day seedlings and the fungicidal effect of the initial concentration and dilutions of 10, 50 and 100 times were determined. The infection process on the 3rd (onset of the disease) and 6th days (intensive development of the disease) was evaluated on leaf segments placed in the studied nanocomposite solutions. They were inoculated by conidia suspension (3-5 thousand/ml) pathogens of net and dark brown spots of barley (Pyrenophora teres and Bipolaris sorokiniana). Seed treatments with nanocomposites did not cause a significant effect on seed germination. The nanocomposites Citrus-Ag pectin in a ratio of 10:1 increased the length and weight of seedlings, Classic-Ag pectin (10:1) undiluted and diluted 10 times increased the shoots length. The nanocomposites in a ratio of 25:1 in all concentrations caused an increase in the length and mass of seedling shoots. On the 6th day the necrotic damage area of leaf segments decreased almost 2 times in 10:1 pectin-silver nanocomposites at initial concentrations and diluted by 10 times compared to the control. During this period the photosynthetic pigments content in the barley leaf segments remained 1.8 - 2 times higher than in the infected control. Incubation on solutions of nanocomposites pectin-silver 10:1 led to a decrease in the oxidative processes’ intensity caused by necrotrophic pathogens at the initial stage of disease development, that contributed to slowing necrosis and preserving the barley leaf segments viability in the model experiment.