Improving resistance against terminal drought in bread wheat by exogenous application of proline and gamma-aminobutyric acid

Scarcity of water is a severe constraint, which hinders the wheat productivity worldwide. However, foliage application of osmoprotectants may be useful in reducing the drought-induced yield losses in wheat (Triticum aestivum L.). In this study, potential of foliage applied osmoprotectants (proline, gamma-aminobutyric acid) in improving the performance of bread wheat against terminal drought was evaluated. Both proline and gamma-aminobutyric acid (GABA) were foliage applied at 50, 100 and 150 mg/L at anthesis stage (BBCH-identification code- 61), in two bread wheat cultivars viz. Mairaj-2008 and BARS-2009. After 1 week of foliage application of these osmoprotectants, drought was imposed by maintaining the pots at 35% water holding capacity. Imposition of drought caused significant reduction in the grain yield of both tested bread wheat cultivars; nonetheless, foliage applied osmoprotectants at either concentration improved the chlorophyll contents, accumulation of proline, glycinebetaine and total soluble phenolics and reduced the malondialdehyde contents, which resulted in better stay green, maintenance of grain weight and grain number under drought stress, thus resulting in better grain yield, water-use efficiency and transpiration efficiency in both wheat cultivars. However, foliage applied proline at 150 mg/L, and GABA at 100 mg/L was most effective than other concentrations of these osmoprotectants. Performance of cultivar Mairaj-2008 was quite better than cultivar BARS-2009. In crux, foliar application of proline and GABA at pre-optimized rate can be opted as a shotgun approach to improve the performance of wheat under terminal drought.