الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Osmotic stress is a serious physiological disorder that affects water movement within cell membranes. Osmotic stress adversely affects agricultural production and sustainability and is largely caused by soil salinity and water stress. Using biostimulants for improving plant growth of medicinal plants grown under stress condition is a critical issue. This experiment was carried out at the Experimental Farm of Agriculture Faculty, Tanta University, Tanta, Egypt, (30° 472 183 N: 31° 002 063 E) and 8 m elevation above sea level during the summer seasons of 2021 and 2022 to assesses the influences of integrated nitrogen fixing bacteria (NFB) soil amendment (NFB0; un-inoculated, NFB1; Bacillus polymyxa, NFB2; Azotobacter chroococcum, and NFB3; Azospirillumlipoferum) and exogenous foliar application of Aloe vera (ALE) and moringa leaf (MLE) extracts on the growth, calyx yield, secondary metabolites, and tolerance to osmotic stress of roselle (Hibiscus sabdariffa L.) cultivated in salt-affected soil. The experiment arranged in split plot design with 12 treatment each one replicated three times. Osmotic stress markedly decreased above-and below-ground growth of the roselle plant, but integrated NFB soil amendment with ALE or MLE foliar application significantly alleviated its negative impacts. Broadly, all applications used decreased chlorophyll and carbohydrates reduction, and enhanced protein content. Also, all applications significantly enhanced the activities of antioxidant machinery (total phenols, ascorbic acid, and FRAP), which positively maintained the oxidative damage (lower MDA and H2O2 accumulation), causing greater salt stress tolerance in plants. Under osmotic stress, the roselle calyx revealed the highest anthocyanin levels, which declined following NFB soil amendment and foliar extracts application. Additionally, an enhancement in N, P, and K contents, and the K/Na+ ratio, along with a depression in Na+ content, were noticed. The integrated application of NFB3×ALE exhibited the best results in terms of enhancing the above-and below-ground growth and recorded the highest calyx yield for both seasons (1406 and 1425 kg ha-1 as compared with 495 and 523 kg ha-1 for control plants). Subjected plants to the treatment of NFB3×ALE revealed the highest antioxidant activity as showed greatest levels of total phenols, ascorbic acid, and FRAP. The highest total chlorophyl, protein, and carbohydrates content was observed by NFB3×ALE treatment. Therefore, it could be recommended that, integrated Azospirillumlipoferumsoil supplementation with ALE or MLE foliar application at 1:30 maximized the growth, productivity secondary metabolites, and increase the tolerance to osmotic stress of roselle plants cultivated under salt-affected soil conditions.