Improvement of drought tolerance in five different cultivars of Vicia faba with foliar application of ascorbic acid or silicon

Aim of study: To explore the role of ascorbic acid (AsA) or silicon (Si) in improving drought tolerance in five faba bean cultivars under irrigation water deficit (IWD). Area of study: The experimental farm; 30 degrees 36' N, 32 degrees 16' E, Egypt. Material and methods: Three drip irrigation regimes (WW, well-watered, 4000 m(3) water ha(-1), MD, moderate drought, 3000 m(3) water ha(-1), and SD, severe drought, 2000 m(3) water ha(-1)) were applied to plants, which were sprayed 25, 40, and 55 days after sowing with 1.5 mM AsA or 2.0 mIVI Si vs distilled water as a control. Main results: TDrought negatively affected physiological attributes (photosynthetic pigments, gas exchange parameters, relative water content, membrane stability index, electrolyte leakage (EL), and lipid peroxidation), which restricted plant growth and yields, and stimulated alterations in both enzymatic and non-enzymatic antioxidant activities. However, AsA or Si application mitigated drought effects on physiological attributes, improving growth, yields and water use efficiency by raising antioxidant activities and suppressing lipid peroxidation and EL in stressful cultivars. The mitigating effects of AsA and Si were more pronounced under MD. Research highlights: 'Nubaria-2', 'Giza-843', and 'Sakha-3' were more tolerant than 'Giza-716' and 'Sakha-4', suggesting the use of AsA or Si to ameliorate the IWD effects on stressful cultivars. Certain physiological traits exhibited positive association with growth and seed yield, demonstrating their importance in enhancing seed yield under irrigation treatments.