Seed priming with hydrogen peroxide enhances tolerance to salt stress of hydroponic lettuce¹

Condicionamento de sementes com peróxido de hidrogênio melhora a tolerância da alface hidropônica ao estresse salino

HIGHLIGHTS:

Seed priming with H₂O₂ increase the salt tolerance in lettuce plants.

The H₂O₂ priming improves water status and increase the chloro-phylls concentration.

The dose of 0.1 H₂O₂ for 12 hours is recommended to decrease the negative effects of salt stress in lettuce plants.

ABSTRACT

Brackish waters has been increasingly used in hydroponic systems for the cultivation of vegetables. However, its use can cause significant losses in crop production. Therefore, new alternatives to enhance the tolerance of plants to salt stress are being studied, including seed priming with hydrogen peroxide (H₂O₂). Thus, this study aimed to assess the seed priming with H₂O₂ at different periods of exposure for enhancing the production, water status and pigments concentration of crisp lettuce grown under salt stress. The experiment was carried out under protected conditions, in a completely randomized design, with four replicates. The plants were cultivated in a floating hydroponic system, containing nutrient solution. Five treatments were tested: control (absence of H₂O₂ and absence of NaCl); salt control (absence of H₂O₂ and presence of 100 mM NaCl); 0.1 mM H₂O₂ (12 hours) + 100 mM NaCl; 0.1 mM H₂O₂ (24 hours) + 100 mM NaCl, and 0.1 mM H₂O₂ (36 hours) + 100 mM NaCl. In general, salinity reduced the height, production of the fresh and dry mass of the shoot, relative water content, and chlorophylls concentration of lettuce plants. However, the application of 0.1 mM H₂O₂ for 12 and 36 hours on the seeds, enhanced the growth, water status, and chlorophylls concentration of the plants. Seed priming with H₂O₂ at a 0.1 mM concentration for 12 hours can be recommended to increase tolerance of lettuce plants grown in a hydroponic system under salt stress.

Key words:
Lactuca sativa L.; H₂O₂; salinity; growth; hydroponics