Influence of Salicylic and Succinic Acids on the Indicators of Growth and Photosynthesis and the Content of Chlorophyll in Wheat Plants Grown under Water Deficiency

In the conditions of climate warming, the frequency and intensity of droughts have increased, therefore, the development of methods that increase the resistance of crops to water scarcity is of great importance. The aim of the work is to study the effect of salicylic and succinic acids on growth indicators, photosynthetic activity indicators and on the content of pigments in the leaves of plants grown under conditions of irrigation and water scarcity. Wheat plants were grown under laboratory conditions. The seeds were pre-soaked in distilled water (control), in a solution of 0.05 mM salicylic acid or in a solution of 0.05 mM succinic acid. After the appearance of the first roots on the 3rd day, the germinated seeds were transferred to 200 ml vegetative vessels filled with soil and grown at 22-24°C in natural light and daily watering. On day 5, the plants were divided into groups “watering” and “water shortage”. The “water shortage” group was stopped watering until the end of the experiment. On day 11, the indicators of the maximum and effective quantum yield of photosystem II, photochemical and non-photochemical quenching and electron flux density were determined using a FRAME-fluorimeter. On the 16th day of growing plants, the quantitative content of chlorophyll a and b and carotenoids was determined, the relative water content in shoots and roots was calculated. The relative water content in plants hardly changed when treated with acids under irrigation conditions, but in case of water deficiency, treatment with succinic acid reduced the water content in the root by 6%. In conditions of lack of moisture, acid treatment increased the effective quantum yield of photosystem II, the photochemical quenching coefficient of chlorophyll and the electron flux density by an average of 17-20%. Under irrigation conditions, treatment with salicylic and succinic acids caused a decrease in the content of chlorophyll a (by 11 and 32%, respectively), carotenoids (by 57 and 32%) and an increase in the content of chlorophyll b (by 49 and 23%). When treated with succinic acid, the total content of chlorophyll a + b decreased by 14%. In conditions of water deficiency, treatment with salicylic acid increased the relative content of chlorophylls and carotenoids by an average of 2.6 and 3.3 times, when treated with amber - by 3.5 and 2.0 times, respectively, compared with the control in terms of raw weight. The use of the studied acids can be recommended for potential use in agriculture.