Nitrogen supplement attenuates drought stress for non-leguminous hybrid plant fescue and does not affect nitrogen-fixing alfalfa

This work focuses on the investigation of forage crops hybrid fescue and legume alfalfa response to drought at different levels of nitrogen fertilization. Plants were grown in pots filled with a mixture of field soil, perlite and fine sand with three (N0, N60 and N90 kg/ha) levels of nitrogen fertilization in a greenhouse. Drought stress was applied by withholding watering for 1 week, after which plants were left for a recovery period of 1 week. In most cases, the morphological indices of alfalfa did not differ significantly between the treatments. In contrast, the above-ground biomass of fescue grown under well-watered conditions was largely enhanced by N addition. The main trend of JIP test parameters was that nitrogen fertilizer did not have a significant effect on alfalfa. Contrarily, additional nitrogen content increased energy fluxes (such as absorption, trapping, electron transport, reduction of end acceptors) and density of reaction centres not only in well-watered but also in drought-affected fescue plants. An increase in nitrogen fertilizers increased content of pigments and flavonoids in fescue leaves. In conclusion, the stress tolerance index of hybrid fescue increased along with the increase in N content due to more efficient use of light energy and increased antioxidative capacity, all of which led to significantly higher production of above-ground biomass at higher N levels and drought stress.

Automated summary

This study found that the effects of nitrogen fertilization on hybrid fescue and legume alfalfa plants were different, with nitrogen having little impact on the morphological indices of alfalfa but significantly increasing the above-ground biomass of fescue plants.