INVESTIGATION OF COST EFFECTIVE SEED PROPAGATION METHODS FOR THE MEDICINAL UANA Coscinium fenestratum Colebr. (Menispennaceae)

Abstract

Coscinium fenestratum colebr. (Menispermaceae) is a widely used medicinal liana in SriLanka and South Asian region. Due to heavy and indiscriminate harvesting from naturalpopulations, this species is endangered in Sri Lanka. In order to reduce the pressure onnatural populations, we attempted to develop rapid and cost effective seed germinationmethods to raise new plants for restoration and rehabilitation programs.

Seeds of C. fenestratum showed all hallmarks of "recalcitrant" seed characters.Considering there initial moisture content and moisture losses. The moisture content offresh seeds was 31 ± 0.6 %. The best method to.conserve moisture content of seeds above25% during storage was by maintaining them in a humid chamber. The viability of seedsdecreased progressively with storage time and the associated moisture loss. Forty daysafter storage, the highest viability (89%) was recorded when seeds were stored in amoisture chamber while the least viability (30%) was recorded when seeds were storedunder ambient conditions. Sixty two percent of seed viability was shown when seeds werestored in polythene bags while the viability was 41% when seeds were stored in paperbags.

Bioassays carried out using seeds of Brassica junceae revealed the presence ofgermination inhibitors in the endosperm and the embryo of C. fenestratum seeds.Germination percentage of B. junceae seeds (used as an indicator to check the inhibitoryaction of C. fenestratum seed) soaked with the water extracts of the endosperm and theembryo of C.fenestratuin were 17% and 25% respectively. B. junceae seeds showcJ 88%germination percentage in the control experiment where the seeds were soaked in water.

In order to evaluate the best seed treatment method that enhance the germination success,fresh seeds were subjected to soaking in a range of gibberllic acid solutions (1500 ppm,2000 ppm, 2500 ppm and 3000 ppm) for 12 hours, mechanical cracking of the seed coat,soaking in tap water for 12 and 24 hours and exposure to sunlight followed by soaking intap water for 12 hours. The highest germination percentage (27%) was shown when seedswere soaked in 2000 ppm gebberllic acid for 12 hours. In all other treatments thepercentage germination was less than 10%.