Seed Priming and Foliar Supplementation with β-aminobutyric Acid Alleviates Drought Stress through Mitigation of Oxidative Stress and Enhancement of Antioxidant Defense in Linseed (Linum usitatissimum L.)

Drought is one of the critical limitations to agricultural soils and crop plants. Scarcity of water is increasing due to climate change that lead to increasing threats to global food security. Therefore, ecofriendly and cost effective strategies are highly desirable for mitigating drought stress along with sustainable and smart agricultural production. The aim of the study was to mitigate DS using seed priming and exogenous supplementation of β-aminobutyric acid (BABA) in linseed (Linum usitatissimum L.). Different doses (0, 50, 100 and 150 µM) of BABA were used for seed priming agent and foliar spraying under three soil moisture levels viz., 25% (SM₂₅), 45% (SM₄₅) and 65% (SM₆₅). The response variables of both experiments included different agro-botanical traits and oxidative stress indicators such as melondialdehyde content, free proline accumulation, and antioxidant defense in plants. The linseed plants showed water stress at SM₂₅ that reduced plant height, number of branches per plant, time taken to flower initiation and heading, and root and shoot dry weights. Additionally, the number of capsules and seeds per capsule showed a significant decline at SM₂₅, which led to a drastic reduction in 100-seed weight yield in linseed plants in both experiments. However, seed priming and foliar supplementation with of BABA (50–100 µM) significantly improved these morpho-agronomical attributes in linseed plants under DS. The results revealed that the BABA was fully active in linseed plants at SM₂₅. Interestingly, the combination of SM₂₅ with BABA significantly improved the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) activity, which significantly enhanced DS tolerance in linseed plants. These findings might be useful to oil seed breeders and farmers linseed for breeding program in linseed plants as well as sustainable agricultural production of oil seed crop plants.