# Low-NaCl pretreatment promotes seedling growth of Chinese white radish under water deficit via osmotic and energy regulation

## TL;DR

Low salt pretreatment helps Chinese white radish seedlings grow better under drought by improving water and energy balance.

## Contribution

The study reveals how low NaCl pretreatment improves seedling growth under water deficit through osmotic and energy regulation.

## Key findings

- Low-NaCl pretreatment increased shoot height, fresh weight, and water content under water deficit.
- Pretreated seedlings showed higher CO₂ production and sugar contents, indicating improved energy status.
- Pretreatment elevated ATP/ADP and ATP/AMP ratios, suggesting better cellular energy homeostasis.

## Abstract

Pretreatment with sodium chloride (NaCl) has been reported to enhance plant tolerance to subsequent water deficit; however, the underlying energy-related mechanisms, particularly during early seedling development, remain insufficiently understood. This study aimed to (1) evaluate the effects of low NaCl and water-deficit conditions on growth, water status, chlorophyll and proline contents in Chinese white radish seedlings, and (2) investigate the influence of NaCl pretreatment on photosynthetic activity, respiratory CO₂ production, sugar accumulation, and cellular energy status under water-deficit condition. Seeds were germinated in sand culture and watered with 0, 10, or 20 mM NaCl for 4 days, followed by transferring the seedlings to 0, − 0.5, or − 1.0 MPa mannitol solutions for 3 days. Growth parameters, water status, chlorophyll and proline contents were assessed in 7-day-old seedlings. Low-NaCl pretreatment enhanced shoot height, fresh weight, yield, water content, degree of succulence and proline content under water deficit. The optimal conditions (10 mM NaCl and − 0.5 MPa) were subsequently used to evaluate Hill’s reaction activity, CO₂ production, sugar contents, and energy status. NaCl-pretreated seedlings exhibited increased CO₂ production; higher fructose, glucose, and sucrose contents; elevated ATP/ADP and ATP/AMP ratios; and a higher adenylate energy charge under water deficit. Overall, the findings demonstrate that 10 mM NaCl pretreatment enhances the growth of Chinese white radish seedlings under water-deficit condition by improving osmotic regulation and maintaining energy homeostasis.

The online version contains supplementary material available at 10.1186/s12870-026-08175-9.