Nitrogen Regulates Rice Seedling Growth, Antioxidants, and Metabolites Under Salt Stress

Area of Science:

• Agricultural Science
• Plant Physiology
• Biochemistry

Background:

• Nitrogen is crucial for rice growth, while salt stress is detrimental.
• Rice varieties exhibit varied responses to nitrogen and salt stress.
• The interaction between nitrogen management and rice salt tolerance is not fully understood.

Purpose of the Study:

• To investigate how different nitrogen levels affect the salt tolerance of diverse rice varieties.
• To analyze morphological, physiological, and metabolomic responses to salt stress under varying nitrogen availability.
• To determine if nitrogen management can be a strategy to enhance salt tolerance in all rice cultivars.

Main Methods:

• Hydroponic experiment with three rice cultivars (Hanyou73, Meixiangzhan2, Xiangyaxiangzhan).
• Treatments included two nitrogen levels (full and 75% reduction) and two salt levels (0 and 100 mmol/L NaCl).
• Evaluated morphological (weights), physiological (pigments, protein, H2O2, antioxidant enzymes), and metabolomic indicators.

Main Results:

• Nitrogen levels significantly influenced rice growth and salt tolerance, with variety-specific effects.
• Low nitrogen increased dry weight in Hanyou73 but decreased it in Xiangyaxiangzhan under salt stress.
• Nitrogen and salt affected photosynthetic pigments, protein content, and antioxidant responses; metabolic pathways like tryptophan and D-amino acid were altered.

Conclusions:

• Nitrogen availability differentially regulates salt tolerance in rice varieties.
• Low nitrogen levels can improve salt tolerance in specific rice cultivars by mitigating reactive oxygen species (ROS) and cellular damage.
• Nitrogen management strategies for salt tolerance must consider individual rice variety characteristics.