Die Invloed van opberging en saadbehandelingsmiddels op die kiemingsfisiologie en fynstruktuur van saad van Brassica oleracea var. capitata

Abstract

The influence of the hot water treatment in conjunction with various storage conditions, on the vigour and ultrastructure of cabbage seed, was studied. The influence of benomyl and thiram as slurry treatments was also investigated. Lastly, the ultrastructure of the cotyledons of chlorotic cabbage seedlings, as a direct result of seed treated with streptomycin, was studied. The hot water treatment was shown to be detrimental to cabbage seed vigour, especially germination rate, when seed was treated before storage and then stored at unfavourable storage conditions. The hot water treatment after storage, and storage under favourable conditions, limited this damage to a large extent. An ultrastructural investigation showed this damage to be similar, although accelerated, to the damage usually encountered during seed senescence, which is largely ultrastructural reorganization of the membranes during early imbibition. A tentative correlation was made between the decline in germination rate and increase in time necessary for ultrastructural reorganization of the membranes during early imbibition. Equilibrating cabbage seed to a relatively low seed moisture percentage (4, 5) also slowed the germination rate, possibly as a result of the increased amount of water to be initially imbibed. No direct negative influence of benomyl and thiram seed treatments could be deduced from this investigation. Treating cabbage seed with streptomycin resulted in seedlings with ultrastucturally abnormal chloroplasts. Although this was prevented by rinsing the seed in NaOCl after the antibiotic treatment, it is not clear whether the NaOCl "repaired" the damage caused by the streptomycin, or prevented the streptomycin action.