Biological green synthesis of silver nanoparticles (AgNPs) from silver salts is a growing advanced approach to
avoid the requirement of costly instruments and involvement of hazardous chemicals as well. However,
increasing use of AgNPs raises potential toxicity level in the environment. In this investigation, leaf extract of
rosemary (Rosmarinus officinalis) used as a reducing and stabilizing agent for biosynthesis of AgNPs. The
biosynthesized AgNPs were authorized by UV-vis spectrophotometer and X-ray diffraction (XRD) analysis. The
shape and size of the biosynthesized AgNPs were studied using high resolution transmission electron microscope
(TEM). The toxicity of the biosynthesized silver nanoparticles on wheat and tomato plants was studied by
soaking wheat grains and tomato seeds in 100 mg/L AgNPs and follow its effect on seedling growth of wheat (at
10 days) and on vegetative growth of tomato and wheat plants (at 35 days). Some physiological parameters as
germination percentage of wheat seedling, length of seedling, dry weight, pigment fractions (chl.a, chl.b and
caroteinoids), soluble proteins, lipid peroxidation (MDA) and antioxidant enzymes (catalase and peroxidase) of
two plants were measured. AgNPs has a non-significant inhibitory effect on germination percentage of wheat,
dry weight and pigment fractions. The biosynthesized AgNPs has a noticeable stress effect on tomato plant as
reduced chlorophyll a and dry weight. Generally, AgNPs stimulate MDA accumulation in tomato and wheat
plants. There was a noticeable different effect of AgNPs on soluble proteins and antioxidant enzymes as catalase
and peroxidase among tomato and wheat plants.

The ability of thiamine (vitamin B1) and ascorbic acid to induce resistance against root rot and wilt disease in safflower cultivar Giza1 infected with Fusarium verticillioides was studied under laboratory and greenhouse conditions. Infection with F. verticillioides caused clear reduction in growth parameters (fresh and dry weight of plants, total photosynthetic pigments), soluble sugars and free amino acids comparing with healthy plants. In addition, it induced the highest accumulation of proline content. On the other side, soaking with two levels of thiamine and ascorbic acid caused reduction in the infected safflower plants and increased dry and fresh weight contents especially in shoots than roots comparing with the infected plants with F. verticillioides. Thiamine concentrations (1,3mM) induced the highest stimulating effect on total pigments. The induction of resistance by ascorbic acid and thiamine was associated with some biochemical changes in safflower cultivar by reduction of proline content, enhancement of soluble sugars and free amino acids, this may be relate to reduce the disease and increase plant growth.

The ability of thiamine (vitamin B1) and ascorbic acid to induce resistance against root rot and wilt disease in safflower cultivar Giza1 infected with Fusarium verticillioides was studied under laboratory and greenhouse conditions. Infection with F. verticillioides caused clear reduction in growth parameters (fresh and dry weight of plants, total photosynthetic pigments), soluble sugars and free amino acids comparing with healthy plants. In addition, it induced the highest accumulation of proline content. On the other side, soaking with two levels of thiamine and ascorbic acid caused reduction in the infected safflower plants and increased dry and fresh weight contents especially in shoots than roots comparing with the infected plants with F. verticillioides. Thiamine concentrations (1,3mM) induced the highest stimulating effect on total pigments. The induction of resistance by ascorbic acid and thiamine was associated with some biochemical changes in safflower cultivar by reduction of proline content, enhancement of soluble sugars and free amino acids, this may be relate to reduce the disease and increase plant growth.

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