Procedure for in vitro seed sterilization, germination and aseptic seedling establishment of Zehneria capillacea (Schumach) C. jeffrey

The most important step in plant tissue culture technique is standardizing a protocol for explant sterilization using phytotoxic sterilants. In this study, two sterilants, sodium hypochlorite (household bleach) and mercuric chloride were evaluated to determine the most suitable concentration and exposure time for explant sterilization of Zehneria capillacea seeds, an undomesticated diploid herbaceous edible cucurbit that is rarely distributed in the Niger Delta region of Nigeria. O.1% mercuric chloride for 1minute and 20% sodium hypochlorite for 15 minutes achieved an efficient (95%) seedling establishment. The study also evaluated the effect of aseptic seed coat removal on in vitro seedling establishment. Seeds with intact coat had 0% germination six weeks after initiation into Murashige and Skoog (MS) medium while all the decorticated seeds showed 100% germination with cotyledonary growth and roots one week after initiation, indicating that the seed coat is a major barrier to the in vitro germination of this species. It was also observed that seed orientation during culture initiation influenced seedling vigor and growth. Three weeks after culture initiation, the aseptic seedlings generated from decorticated seeds were observed to have grown 4-5 cm in height with formation of tendrils, apical and axillary nodes, which could be used as explant source for various in vitro culture studies such as callus induction, shoot multiplication, in vitro polyploidization and production of secondary metabolites.