Chemical root pruning by copper salts on vegetables: a possible way to improve the seedling quality.

摘要

Large part of vegetable species are currently transplanted. In some species, it is quite common to observe, on seedlings ready to out planting, an overgrowth and root spiralling. That fact causes difficulties during the transplant operations and a reduction in physical or environmental stress resistance when the seedlings are planted in open field. In order to investigate the effectiveness and the phytotoxicity on vegetable seedlings of chemical root pruning and the long terms effects, trials were carried out on asparagus, chicory, celery, fennel, lettuce and parsley. The effects of different chemical compounds, doses, salt mode of application to the container and binding materials were studied both in nursery and in open field. The copper salts, used as a coating for the interior walls of the tray, reduced significantly the root development, and improved the seedling extraction from the plug. Among the different salts evaluated, copper sulphate was the best compound in terms of effectiveness and cost. The doses tested ranged from 0.3 to 2.5% of copper; the genotypes answered in different way to the application so the right concentration changes with species and cultivar. Regarding the salt mode of application, no clear differences were found between spraying or dipping the entire container in the salt solution. Finally, the use of binder materials like surfactants or glue did not give different results in terms of root growth reducing, plug extraction and seedling quality. Phytotoxicity was observed only at highest doses as excessive root growth reduction; no detrimental effects were observed on the final market yield obtained from the seedlings treated with the right amount of copper.