Genetic Consequences of Plant Propagation Methods in Indonesian Selective Cutting and Planting System: A case study in Shorea johorensis Foxw

Abstract

Attempts to rehabilitate degraded natural forests in Indonesia are recently carried out by applying selective cutting and line planting system. One of the most important aspects in this silvicultural system is the procurement methods for large number of planting stocks. Shorea johorensis was investigated in this regards as one of the recommended Shorea species for forest rehabilitaton due to its fast growing character. The species is usually propagated by three different propagation methods, namely up-rooted seedlings, seeds and cuttings (stecklings). Genetic consequences due to application of different propagation methods in tlns species are poorly known and need to be investigated to determine genetic variation and differentiation. Materials from five origins (populations) in a forest concession holder in Central Borneo, namely: i) uprooted seedlings, ii) seeds, iii) cuttings, iv) young plantation line and v) natural forest were randomly taken in the field and subsequently assessed by RAPD technique using three previously tested random primers of OPO-11, OPO-13 and OPO-16. Results showed that among 5 populations investigated, natural tree populations showed the lnghest levels of genetic variation with mean values na = 1.2593, ne = 1.2070, PPL = 25.93% and He = 0.1109. Cutting populations showed the lowest levels of genetic variation with mean values na = 1.1111, ne = 1.0773, PPL = 1l.11 % and He = 0.0445. Meanwhile, according to the propagation methods, up-rooted seedling population revealed the highest levels of genetic variation with mean values na = 1.2222, ne = l.1613, PPL = 22.22% and He = 0.0886. Values of ne and He in natural forest were higher (ne = 1.2070 and He = 0.1109) than those of young plantation line (ne = l.1609 and He = 0.0896). The closest genetic distance was observed between population of seeds and cuttings, namely 0.0590. It was found that a particular procedure to propagate planting stocks at large scale in this company, i.e. cutting propagation method, tended to reduce genetic variation.