Abstract
BACKGROUND: Seed priming is an affordable and effective method to enhance crop drought tolerance by improving seed germination and seedling vigor. However, whether seed priming alters cuticle formation, which could contribute to drought resistance in seedlings, remains unclear. MATERIALS AND METHODS: In this study, sweet sorghum seeds belonging to three varieties were primed with salicylic acid (SA) and the seedlings were exposed to drought stress. The seeds were primed with SA with concentrations of 50, 100, 150, 200, 250 mg L(-1). For drought treatment (35% field capacity, 80% of field capacity as the normal condition), both SA-primed and non-primed seeds were planted in a soil mixture. RESULTS: Under drought conditions, SA priming at 150 mg L(-1) significantly increased total wax content (12.3%-33.3%), primary alcohol content (42.0%-57.0%), proline content (70.9%-119%), leaf water content (9.8%-36.6%), water use efficiency (28.4%-120%), and biomass (25%-30%). Additionally, leaf water loss rate and chlorophyll leaching rate were significantly reduced. Correlation analysis revealed strong positive associations (r = 0.79-0.86, P < 0.001) between total wax content and water status as well as proline content. Furthermore, under both well-watered and drought conditions, SA priming at 150 mg L(-1) significantly increased leaf wax content and biomass in all sorghum varieties. CONCLUSION: Seed priming with salicylic acid at 150 mg L(-1) not only promotes normal growth under well-watered conditions, but also enhances sorghum's adaptability to drought stress, ultimately contributing to drought tolerance without penalizing growth.