Arbuscular Mycorrhizal Colonization Enhanced Early Growth ofMallotus paniculatusandAlbizia samanunder Nursery Conditions in East Kalimantan, Indonesia

Forest over logging, forest fire, forest conversion, and opencast mining have promoted deforestation in Indonesia, and reforestation is needed immediately. However, reforestation is limited by low seedling quality and production, and slow seedling growth in nurseries. Native tropical tree and fast-growing species, Mallotus paniculatus and Albizia saman, are potential to promote the first rotation of reforestation. Arbuscular mycorrhizal (AM) fungi are known to promote nutrient uptake and plant growth. We examined the effects of two native AM fungi, Gigaspora decipiens and Glomus clarum, on the growth of M. paniculatus and A. saman seedlings under nursery conditions. At harvest, after six months, we determined AM colonization, shoot dry weight, and shoot N and P concentration. Approximately 90% and 50% of M. paniculatus and A. saman roots, respectively, were colonized by AM fungi, without any difference between the inoculation treatments. G. decipiens and G. clarum increased shoot height, leaf number, shoot dry weight, and shoot N and P uptake of both species. A positive correlation was observed between N and P uptake and shoot dry weight. These results suggest that AM fungi are effective in accelerating nutrient uptake and plant growth, which will, in turn, promote reforestation and sustainable forest timber production