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Drought-tolerance mechanisms in foxtail millet (Setaria italica) and proso millet (Panicum miliaceum) under different nitrogen supply and sowing dates

Nematpour, Afsaneh, Eshghizadeh, Hamid Reza, Zahedi, Morteza
Crop & pasture science 2019 v.70 no.5 pp. 442-452
Panicum miliaceum subsp. miliaceum, Setaria italica, adverse effects, antioxidant activity, biochemical pathways, carotenoids, chlorophyll, drought tolerance, enzyme activity, evaporation, fertilizer rates, grain yield, hydrogen peroxide, irrigation management, lipid peroxidation, malondialdehyde, millets, nitrogen, nitrogen fertilizers, nutrition, osmoregulation, planting date, proline, soil water, sowing date, temperature, water stress, water supply
Drought stress is one of the main limitations to crop growth and yield. Efficient nitrogen (N) nutrition may moderate the negative effects of drought stress on plants through retention of metabolic activities. The present study was conducted to investigate the biochemical responses of two millet species, foxtail millet (Setaria italica (L.) P.Beauv.) and proso millet (Panicum miliaceum L.), under two irrigation regimes (based on 55% and 85% soil-water depletion) and two N fertiliser levels (0 and 112.5 kg N ha–¹) at four sowing dates (22 June and 6 July 2015, 14 and 30 June 2016). Drought stress increased hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and other aldehyde contents of the plants, ultimately leading to 52% and 55% reductions in grain yield in foxtail millet and proso millet, respectively. Antioxidant activities showed significant increases under drought stress. Nitrogen application decreased H₂O₂, MDA and other aldehyde contents and activities of antioxidant enzymes, whereas it increased chlorophyll, carotenoid, phenolic compound and proline contents as well as grain yield. Higher grain yields were obtained with early planting dates under sufficient water supply, whereas superior yields were obtained with delayed planting dates under water stress owing to lower temperatures and evaporation rates. The results suggest that N application could mitigate the adverse effects of drought stress on millet plants by promoting osmoregulation, alleviating lipid peroxidation, and improving plant physiological traits. Foxtail millet had higher antioxidant potential than proso millet, resulting in greater capacity to inhibit production of free oxygen radicals and making it the more drought-tolerant species.