Magnesium and organic biostimulant integrative application induces physiological and biochemical changes in sunflower plants and its harvested progeny on sandy soil

Magnesium (Mg) often leaches down in sandy soils due to high mobility and its foliar application proves to be beneficial. Organic biostimulants also prove to be helpful to affect plant physio-biochemistry and antioxidative defense system. The present study evaluated the beneficial effects of seed soaking in maize grain extract (MGE; 3%) in integration with or without foliar Mg (1 mM) in comparison to control (no treatment) on growth, yield performance, seed oil and fatty acid profile including physiological and biochemical basis of Hysun-336 sunflower hybrid grown on a sandy soil under greenhouse conditions. The integrative treatment (seed soaking in MGE + foliar spray with Mg) elevated growth traits, plant water status and membrane stability index, and reduced electrolyte leakage. Improved leaf contents of chlorophylls, carotenoids, total soluble sugars and proline, activities of non-enzymatic and enzymatic antioxidants were also observed. In addition, enhanced uptake of N, P, K including Mg and endogenous levels of plant hormones IAA, GA3 and zeatin were recorded with the integrative treatment. Seed yield and oil contents including oleic (mono-unsaturated) and linoleic (poly-unsaturated) fatty acids also increased; however, a decrease in other saturated, mono-unsaturated and poly-unsaturated fatty acids was noticed. Improved seed and seedling vigor traits were also observed in progeny of sunflower that harvested from the integrative treatment. In summary, improved plant performance by the integrative treatment may be attributed to improved activities of antioxidants contributing to improved plant water content, nutrient uptake and endogenous hormonal levels in sunflower plants grown under sandy soil conditions.