STUDIES ON DORMANCY AND GERMINATION DYNAMICS OF Macaranga peltata(KANDA), AN EARLY SUCCESSIONAL SPECIES

Abstract

Macaranga peltata is one of the most widely occurring early successional woodyspecies, specially in low country wet zone. Although Macaranga spreadsprofusely by seeds, the seed biology and germination behavior has not beenstudied. According to the preliminary studies, it was revealed that, thegerminability of freshly isolated seeds is very low. Therefore this work wasundertaken to understand the germination behavior and measures to enhance seedgermination of Macaranga. The study was conducted during May-July, 2000, atthe faculty of Agriculture, University of Ruhuna, Mapalana, kamburupitiya, SriLanka.

Three treatments used, i.e. mechanical scarification using sand papers (T I),Chemical scarification using H2S04 acid (T2) and hormone treatment using GA(T3)' with the control. Fully ripened seeds were harvested and thoroughly washedto remove the peel and air-dried for one day. Dried seeds were treated asindicated above and placed in petri dishes containing sand media and allowed togerminate. Three replications were used for each treatment and percentage ofgermination was recorded at 7,14,21 and 28 days after planting.

Germination of Macaranga seeds started after 14-21 days in control by afterseven days in treated seeds. Mechanical and chemical scarifications were noteffecting in increasing the percentage of germination significantly. But thegibberelic acid treatment has made a tremendous important in the percentage ofgermination and at the same time resulted in significant reduction it time taken forgermination. Although scarification treatments may have improved permeabilityof seed coat, it has not contributed to the germinability of seeds, the significantimpact made by GA treatment both in increasing and accelerating the germinationprobably reveals that there exists a dormancy in Macaranga seeds which is ofphysiological or metabolic in nature GA treatment of more effectively at higherconcentration: (20mm) was capable of breaking the dormancy and thus enhancedgermination.