Adaptive reactions of wheat plants to drought conditions under the influence of salicylic acid

Background. Drought is one of the most important factors affecting plant growth and productivity. The study addressed the perspectives of usage of salicylic acid, a stress protective compound, to increase the adaptive potential of Triticum aestivum L. plants under drought conditions. The effect of salicylic acid on the photosynthetic apparatus of wheat plants under the conditions of drought with a subsequent gradual resumption of watering was investigated. Materials and methods. Plants of the Podolyanka variety of wheat (Triticum aestivum L.) were the objects of our study. Seeds were pre-soaked in a solution of salicylic acid (50 mM) for 3 h. First seeds germinated in an incubator, and on the 3rd day of growth were transplanted into plastic pots (d = 14 cm). Plants were grown on soil substrate, whose humidity was maintained at 60 % of full moisture capacity – the optimal water supply. The model of drought was created by the simultaneous cessation of irrigation (30 % of soil moisture capacity) for 12 days. Upon termination of the drought, soil moisture in the pots was adjusted to 60 % of its full capacity. The control plants were grown from the seeds not treated with salicylic acid under conditions of optimal water supply (60 %). Study samples were taken from the shoots of wheat on the 7th, 9th and 12th days of the drought period and on the first day after the resumption of irrigation (14 days). The concentrations of TBA-active products, chlorophyll, carotenoids, glucose, sucrose and chlorophyllase activity were determined. Results. The influence of salicylic acid on the content of chlorophyll, carotenoids and TBA-active products along with chlorophyllase activity in shoots of wheat under the drought conditions on the early stages of ontogenesis was determined. It was found that both drought and salicylic acid modify the content of chlorophyll and carotenoids in the shoots of Triticum aestivum L., apparently by altering their metabolism. Chlorophyllase plays an important role in the adaptation of photosynthetic apparatus to the drought conditions. Our results suggest that salicylic acid causes an increase in the content of photosynthetic pigments and a decrease in chlorophyllase activity in drought conditions. In addition, salicylate causes the accumulation of glucose and sucrose in the shoot tissues of wheat plants under stressful conditions. Conclusions. Our research suggests participation of salicylic acid in the plants’ adaptation processes under the conditions of moisture deficiency. It was also found that under the effect of salicylic acid the content of TBA-active products decreases in the plant shoots under the conditions of drought. Considering the fact that the content of TBA-active products is an important indicator of lipid peroxidation intensity, the decrease of this index reveals the reduced activity of free radical processes in plant tissues under the effect of salicylic acid. Thus, it can be assumed that SA has a positive effect on plant metabolism under drought conditions

Specific manifestation of enzymomycotic depletion of grain on crop losses

Background. Enzymomycotic depletion of grain leads to a significant decrease in the dry matter mass of the grain, as the intensity of respiration increases, protein substances break down, enzymes (in particular, α-amylase) pass from the adsorbed form to the water-soluble one, and their activity increases sharply. One of the consequences of this is the intensive amylolysis of starch, which means a significant deterioration in the technological indicators of the quality of grain and seeds. Materials and Methods. This study gives a thorough description of the process of enzymomycotic depletion of grain of soft winter wheat (Triticum aestivum L.), sowing rye (Secale cereale L.), winter triticale (Triticosecale Witt.) depending on abiotic factors and the sources of resistance to ear diseases 4, 8, 12 days after the onset of full ripeness in the conditions of the western forest-steppe of Ukraine (2019–2021). Research methods – general scientific, field, measurement and weight, mathematical and statistical. Results and Discussion. According to the obtained results, the dependence of enzymomycotic depletion of grain on abiotic factors was established. The development of ear diseases depended both on weather factors and on the ecological plasticity of the cultivar. The highest percentage of the distribution of ear sepsoria was observed on the 12th day after the onset of full ripeness: wheat – 3.3 %, rye – 2.4 %, triticale – 1.9 %, fusarium, respectively 2.4 %, 1.9 %, 1 %, 8 %. The loss of dry matter in the weight of 1000 grains depended on the ecotype of the cultivar and the duration of the grain stan­ding time 4, 8, and 12 days after full ripeness. Conclusion. The following cultivars were most resistant to EMDG: Oberih Myronivsky (wheat), Kobza (rye), Obrij Myronivsky (triticale); their base seed production profitability rates being 75.1 %, 116.6 %, and 146.8 %, respectively. The results of the study can be used in the selection of varieties of winter grain crops resistant to enzymomycotic grain depletion for the western forest-steppe and Polissya zones of Ukraine, where breeding work on these crops is not carried out and agricultural producers purchase seeds of new varieties from the originating institutions of the central forest-steppe to introduce them into production