Changes in the pigment composition of barley leaves during adaptation to water deficiency after super-high frequency treatment

Abstract

Drought affects the most important metabolic reactions in the plant body and triggers a cascade of adaptive reactions. Adaptations to water deficiency refer to various life-supporting processes, for example, the assimilation apparatus. Super-high frequency electromagnetic field may be used as a stressor that triggers preliminary adaptation reactions. The research goal is to study the peculiarities of changes of the pigment composition of barley leaves during adaptation to water deficiency after super-high frequency treatment. In order to achieve the research goal, a vegetation experiment was carried out. After electromagnetic treatment (power modes: 420 and 700 W), the seeds were sown in pots with a soil mixture. Starting from the 15th day, watering was stopped in the variants simulating drought conditions. At the age of 1 month, the aboveground herbage was cut off and the pigment content was determined by photometric method without their preliminary separation from the total acetone extract. Under normal moisture conditions, the high power of electromagnetic treatment leads to a dramatic decrease of the amount of chlorophyll a - 1.70 times. Water deficiency leads to decreased amount of green pigments and a slight increase in the content of yellow ones relative to plants that developed under normal moisture conditions. At the same time, the sum of all photosynthetic pigments decreases by 5.99%. Water deficiency leads to significant imbalance of the assimilation apparatus - the ratio between chlorophylls and carotenoids decreased 1.59 times. Even more severe violations of the pigment apparatus of barley are found when two factors are applied - osmotic stress and high power of super-high frequency energy. In this combination, the treatment does not compensate for the disorders that develop under the influence of water deficiency but exacerbates them. On the contrary, the medium-power super-high frequency treatment mode is able of leveling the negative effects of osmotic stress by enhancing the synthesis of photosynthetic pigments. Moreover, the sharpest increase was found for carotenoids which in addition to their actual participation in photosynthesis perform an antioxidant role. The obtained data will allow to purposefully influencing the pigment composition of barley.