The role of the dry scale in the dormancy of onions (Allium cepa L)

Colour, thickness and the number of the dry scales of onion are genetically determined. Environment and agrotechnics may be modifying factors. Investigations have been made into the variety characteristics and their role in keeping quality in storage. Experiments have been carried out for studying the influence of harvest time on dry scale number and colour. The firmness of the bulb, as affected by the firmness of the dry scale, has been examined too. Investigations have been accomplished for clearing the role of the dry scale in the dormancy of the onion. Provocative experiments have been made in order to break dormancy in an environment of high humidity and temperature conditions, as well as by removing the dry scale and by injuring the bulbs artificially. The effects of the different treatments have been evaluated regarding the beginning and the rate of rooting and sprouting. The quantities of germination inhibiting substances in the dry scale have been determined in a simple trial. The seeds have been treated with a solution gained from soaked dry scale and the conclusions on the quantity of inhibitors have been made on the basis of the germination results. The tests have been linked with storage experiments in order to find out if storability is related to dry scale quality. The experimental results have led to the conclusion that dry scale quality is one of the determinant factors in the storability of onions and it has a significant role in keeping dormancy.