Chloride reduces plant nitrate requirement and alleviates low nitrogen stress symptoms

• Published in: Plant physiology and biochemistry Vol. 212; p. 108717
• Main Authors: Lucas, Marta, Diaz-Espejo, Antonio, Romero-Jimenez, David, Peinado-Torrubia, Procopio, Delgado-Vaquero, Alba, Álvarez, Rosario, Colmenero-Flores, José M., Rosales, Miguel A.
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01-07-2024
• Subjects: Antioxidants; Antioxidants - metabolism; Chloride; Chlorides - metabolism; Nitrate; Nitrates - metabolism; Nitrates - pharmacology; Nitrogen - metabolism; Photosynthesis; Photosynthesis - drug effects; Plant Leaves - drug effects; Plant Leaves - metabolism; Solanum lycopersicum - drug effects; Solanum lycopersicum - growth & development; Solanum lycopersicum - metabolism; Stress; Stress, Physiological - drug effects; Tomato; Water - metabolism; Water status; Antioxidants; Water status; Chloride; Nitrate; Photosynthesis; Tomato; Stress
• ISSN: 0981-9428; 1873-2690; 1873-2690
• DOI: 10.1016/j.plaphy.2024.108717

Chloride (Cl−) is traditionally categorized as an antagonist of nitrate (NO3−) because Cl− hinders plant NO3− transport and accumulation. However, we have recently defined Cl− as a beneficial macronutrient for higher plants, due to specific functions that lead to more efficient use of water, nitrogen (N) and CO2 under optimal N and water supply. When accumulated in leaves at macronutrient levels, Cl− promotes growth through osmotic, physiological, metabolic, anatomical and cellular changes that improve plant performance under optimal NO3− nutrition. Nitrate over-fertilization in agriculture can adversely affect crop yield and nature, while its deficiency limits plant growth. To study the relationship between Cl− nutrition and NO3− availability, we have characterized different physiological responses such as growth and yield, N-use efficiency, water status, photosynthesis, leaf anatomy, pigments and antioxidants in tomato plants treated with or without 5 mM Cl− salts and increasing NO3− treatments (3–15 mM). First, we have demonstrated that 5 mM Cl− application can reduce the use of NO3− in the nutrient solution by up to half without detriment to plant growth and yield in tomato and other horticultural plants. Second, Cl− application reduced stress symptoms and improved plant growth under low-NO3− conditions. The Cl−-dependent resistance to low-N stress resulted from: more efficient use of the available NO3−; improved plant osmotic and water status regulation; improved stomatal conductance and photosynthetic rate; and better antioxidant response. We proposed that beneficial Cl− levels increase the crop ability to grow better with lower NO3− requirements and withstand N deficiency, promoting a more sustainable and resilient agriculture.
•This study focuses on the study of the physiological responses of plants to chloride and nitrate nutrition.•Chloride can partially replace nitrate application maintaining growth and yield in several horticultural plants.•Symptoms of low nitrogen stress are alleviated by chloride nutrition at macronutrient levels.•The better chloride-dependent water status sustains plant growth and photosynthesis under low nitrogen stress conditions.