Citric Acid and Hydro-Priming and Exogenous Application Alleviate Salt-Inhibited Seed Germination and Seedling Growth of Chilli (Capsicum annuum L.)

Abstract

Salinity is a major barrier for seed germination, plant growth and production. Seed pre-treatment and exogenous chemical usage can effectively confer salt tolerance. We evaluated the potential of citric acid (CA) as priming and exogenous agents to ameliorate salt-inhibited germination and growth of Chilli (Capsicum annuum L.) in this study. The seeds were primed with 0.5 mM and 1 mM CA, and soaked in distilled water (hydro-priming) for 30 min. In addition, untreated seeds were used for the control experiment. Finally, primed seeds were subjected to 100 mM NaCl stress. Our results demonstrated that salinity significantly reduced the germination percentage (GP), germination index (GI), germination energy (GE), seed vigor index (SVI), root length (RL), shoot length (SL), shoot–root fresh and dry weight, and plant height and increased mean germination time (MGT). The results also indicated that salinity stress considerably decreased the relative water content (RWC) and photosynthetic pigments such as chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids, and increased relative water loss (RWL). The CA- and hydro-priming improved the GP, GI, GE SL, RL, SVI, and growth of seedlings, and reduced MGT under salt stress. Data also demonstrated that the supplementation of CA enhanced RWC and photosynthetic pigments and lowered RWL in the state of saline condition. When compared to other treatments, pretreatment, and exogenous use of 1 mM CA was determined to be comparatively more effective at imparting the salt tolerance of Chilli.