Pepper (Capsicum annuum) seed germination and vigour following nanochitin, chitosan or hydropriming treatments

Fast germination and vigorous early seedling growth are essential for establishment of pepper (Capsicum annuum), a warm season crop that germinates poorly under cold conditions. Three experiments compared effects of seed treatments on 'California Wonder' bell pepper seed germination percentage, mean time to germination (MTG), seedling emergence in a modified AOSA cold test (at 10°C for seven days before transfer to 25°C for 14 days), and germination in soil at 19, 22, 26 and 30°C on a thermogradient table. Seeds were treated by hydration for 24 hours in aqueous nanochitin suspensions or chitosan solutions (0.001, 0.01 and 0.05% w/v), 1% acetic acid, hydroprimed in distilled water, or treated with 1% Captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide, 50% wettable-powder) fungicide. All seeds were dried back to their original moisture content before germination testing. Treatments with nanochitin or hydropriming reduced MTG to 4.9-5.3 days compared with 5.4-6.7 days for other treatments or untreated seeds at 25°C on blotter paper. Nanochitin, chitosan, acetic acid or hydropriming treatments enhanced low temperature emergence compared with Captan-treated or untreated seeds. Treatments with 0.05% nanochitin or hydropriming improved seedling emergence at 19 to 30°C. Hydroprimed seeds germinated faster with improved emergence similar to nanochitin, but nanochitin also visibly reduced fungal growth.