Bio-priming mitigates detrimental effects of salinity on maize improving antioxidant defense and preserving photosynthetic efficiency

Salinity is an abiotic stress which seriously affects crop production over the world, particularly in arid and semi-arid regions, with harmful effects on germination, growth and yield. Maize (Zea mays L.), cultivated in a wide spectrum of soil and climatic conditions, is the third most important cereal crop after rice and wheat, moderately sensitive to salt stress. A saline level more than 250 mM NaCl damages maize plants, causing severe wilting. In this study, the effects of hydro-priming (distilled water) and bio-priming (Rosmarinus officinalis L. and Artemisia L. leaf extracts) on seed germination and seedling growth of maize, under 100 mM NaCl salinity were investigated. The factorial experiments were carried out in greenhouse under controlled condition (25 °C in 12/12 h day/night) based on a completely randomized design with three replicates. Results showed that both hydro- and bio-priming increased germination percentage and germination indexes in maize seeds. Rosmarinus extract was the most effective in inducing salt resistance in 30 days old seedlings, with beneficial effects in the strengthening of the antioxidant system and in the maintenance of a higher photosynthetic efficiency under salt stress condition.