Subsequent drought and re‐watering events cause a shift in productivity and nutritive value of alfalfa and hybrid fescue plant

Abstract

Global climate change leads to increasing frequency of droughts, threatening the productivity and quality of forage plants. Therefore, this glasshouse experiment was conducted to investigate the effects of reoccurring droughts on productivity and nutritive value of alfalfa and hybrid fescue plants. Starting from 63 days after sowing, seedlings of plants were exposed to double drought‐recovery treatments, each separate period lasting for 1 week. At the end of each treatment, growth of above‐ and below‐ground dry weight, lipid peroxidation, total antioxidative capacity, content of polyphenols, soluble and insoluble carbohydrates and proteins, as well as elemental composition of shoots were investigated. The findings confirmed our hypothesis, as growth of both plant species were mostly insignificantly affected by subsequent drought events. Whereas effect on leave redox homeostasis and plant nutritive value was much stronger, highly depending on both plant species and the order of stress event. We found significant drought‐induced increase in the content of water‐soluble carbohydrates (WSCs), starch, soluble and insoluble proteins, and polyphenols. Water shortage tended to decrease and increase the content of most macro‐ and microelements in alfalfa and fescue, respectively. These effects were reversed by re‐watering with several exceptions, such as constant reduction of Ca content in alfalfa. To conclude, alfalfa was found to be more sensitive than fescue to the first drought, but able to recover after both stress events. The second drought‐initiated prolonged accumulation of WSC implies a shift in plants metabolism towards increased resistance and herewith nutritive value with respect to soluble sugars.