Foliar application of alpha-ketoglutarate plus nitrogen improves drought resistance in soybean (Glycine max L. Merr.).

The aim of the present research was to understand the impacts of foliar nitrogen and α-oxoglutarate on proline accumulation, photosynthesis, and ammonium assimilation of soybean seedlings subjected to drought stress. The data in the present study demonstrated that foliar α-oxoglutarate and nitrogen significantly enhanced leaf glutamine synthetase (GS) activity, glutamate dehydrogenase (GDH) activity, glutamate content, proline content, relative water content (RWC) and photosynthesis of soybean seedlings exposed to drought stress at each stage. Accordingly, the ammonium content was significantly reduced by foliar α-oxoglutarate and nitrogen. These results suggested that a combination of foliar nitrogen plus α-oxoglutarate had an advantage over either foliar nitrogen or foliar α-oxoglutarate in increasing the proline accumulation under drought stress and a combination of foliar nitrogen plus α-oxoglutarate could better mitigate the adverse impacts of drought stress.