Exogenous Ca2+ alleviates nitrogen and water deficit, and improves growth of wheat ( Triticum aestivum) seedlings exposed to high temperature.

This study was designed to examine whether exogenous Ca²⁺ would improve nitrogen nutrition, water status and growth of high temperature (HT)-stressed wheat ( Triticum aestivum) seedlings. Wheat plants were exposed to 35/30 and 25/20°C as temperature control. Some of HT-stressed plants were simultaneously treated with 4 mM Ca²⁺. External Ca²⁺ could obviously improve growth of HT-exposed wheat seedlings indicated by the biomass. Compared with Ca²⁺-untreated plants, total nitrogen content showed a significant increase in Ca²⁺-treated plants under HT stress, this primarily resulted from enhanced nitrate reductase activity and depressed loss of ammonium through photorespiration. External Ca²⁺ application could also increase leaf relative water content and alleviate osmotic stress via increased K⁺ ion and water-soluble carbohydrates in HT-stressed plants. Whereas free proline content showed remarkable decline in Ca²⁺-treated plants at HT stress. [ABSTRACT FROM AUTHOR]