Pemanfaatan Mycorrhizal Helper Bacteria (MHBs) dan Fungi Mikoriza Arbuskula (FMA) untuk Meningkatkan Pertumbuhan Semai Gmelina (Gmelina arborea Roxb.)

Abstract

INTRODUCTION. Increase in the size of human population causes an ever increasing demand on paper produtcs. Therefore, there is a need to supply wood as raw materials in rapid manner. In relation with this, the Indonesian government has a policy to develop Industrial Plantation Forest (HTI). Gmelina is one of the forest tree species which has good prospect to be developed in Industrial Plantation Forest (HTI). This species is a fast growing species which could grow in various types of soil, and its wood is considerably useful. Development ofHTI in Indonesia is emphasized on critical land. The use of Arbuscular Mycorrhizal Fungi (AM F) is an appropriate solution for promoting plant growth in such condition. In the field, AMF had some constraints in creating symbiosis with host plants, Therefore, in this case, there is a need for bacteria which stimulates the AMF. One such bacteria, is known with the name Mycorrhizal Helper Bacteria (MHBs). MATERIALS AND METHOD. This research used Factorial Completely Randomized Design comprising 16 treatments, 5 replications and 3 units. Inoculation of mycorrhizal fungi and bacteria was conducted when the seedlings were 3 weeks old. Afterwards, observation was conducted for 3 months. For observing the plant's respond toward treatments, the observed parameters were among other things: height, diameter, root biomass, shoot biomass, shoot - root ratio, Index of Seedling Quality, and percentage of mycorrhizal infection. RESULTS AND CONCLUSION. Results of Analysis of Variance showed that mycorrhizal treatment had significant effect on parameters of root biomass and percentage of mycorrhizal infection. On the other hand, combined treatments of mycorrhiza and bacteria had significant effect toward parameter of root biomass. Combination of mycorrhiza with isolate BGLo3 gave the highest percentage of mycorrhizal infection, namely 25.49 %. Inoculation of isolate BGLo1 gave the best respond for parameters of height and diameter. Consecutively, the exhibited increases were 32.33 % and 31.25 % as compared with those of control. Combination of mycorrhiza with BGLo3 also exhibited the highest increase as compared with control, in terms of parameters of root biomass and Index of Seedling Quality, namely 2.28 % and 87.89 %. Inoculation ofmycorrhiza without bacteria exhibited the best respond for parameters of shoot - root ratio, namely with increase by 9.23 % as compared to control.