The Effect of Phytohormonal Steroids in Combination with Succinic Acid on the Resistance of Hordeum Vulgare L. to Helminthosporium teres Sacc.

The aim of this investigation is study the BS effect on the growth of Helminthosporium teres Sacc. and to elucidate the protective effect of brassinosteroids and their tetrahemisuccinates on spring barley (Hordeum Vulgare L.) exposed to biotic stress caused by this phytopathogenic fungus.

Brassinosteroids and their tetrahemisuccinates are considered as protectors of the fungal infection caused by H.teres.

Evaluation of the effect of brassinosteroids, their mixtures and conjugates with succinic acid against the pathogen H.teres, as well as in spring barley crops against a natural infectious background.

The fungistatic activity of brassinosteroids and their tetrahemisuccinates was evaluated in relation to the phytopathogenic fungus H.teres. The effect of BS and their derivatives on the processes of adaptation of spring barley plants to the pathogen of net spotting of the phytopathogenic fungus H.teres was studied on a model pathosystem and in the agrocenosis.

A fungistatic activity of the synthesized substances was revealed, which consists in inhibiting the growth of the phytopathogenic fungus H.teres on a solid nutrient medium by 35-40%. Succinic acid can enhance the fungistatic effect of brassinosteroids, which is more noticeable when using conjugates with succinic acid than in mechanical mixtures. In field experiments, it was shown that the studied compounds and their mixtures applied as a single spraying in the beginning of tubing phase reduced the development of leaf spots caused by phytopathogenic fungi.

The results obtained indicate that brassinosteroids with succinic acid both in the form of conjugates and mechanical mixtures show fungistatic activity.