Treatment of bell pepper (Capsicum annuum L.) seeds with chitosan increases chitinase and glucanase activities and enhances emergence in a standard cold test

Abstract

Pepper (Capsicum annuum), as a warm-season crop, germinates poorly under wet and cold soils due in part to seed fungal diseases. The objective of this study was to test whether seed treatment with chitosan improved low temperature germination by increasing chitinase and glucanase activities. Pepper seeds were imbibed in 0.01, 0.05, 0.1, 0.3, and 0.5 % chitosan solutions, 1 % acetic acid, 1 % Benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazole] fungicide, or hydroprimed in distilled water for comparison with dry-untreated seeds. After treatment, all seeds were slowly dried back to their original moisture content and evaluated for germination percentage, mean time to germination (MTG), seedling growth in a warm germination test and for seedling emergence in a standard cold test. Chitinase and glucanase activities were also measured for seeds after treatment and for germinating seedlings. Seeds treated with chitosan or hydroprimed germinated faster with decreased MTG compared to untreated seeds germinated at 25 °C and produced longer seedlings with greater fresh weights. Treatment of seeds with chitosan significantly improved final germination percentage by 8% in the second lab experiments (≥90 %). Seed treatment with chitosan or hydropriming improved seedling emergence in the cold test by 29 %. Seed treatment with chitosan increased chitinase and glucanase activities in both seeds and seedlings compared to untreated seeds. In conclusion, treatment of pepper seeds with chitosan improved seed germination under wet and cold conditions, which might be due to the induction of systemic acquired resistance in seeds by increasing chitinase and glucanase activities. Greater chitinase and glucanase activities in chitosan-treated seeds might protect seedlings from fungal diseases under cold conditions.