Establishment of Vegetatively Propagated Khaya anthoteca Pre-Inoculated with Arbuscular Mycorrhizae Fungi (AMF) On an Ex-Coal Mined Site.

Abstract

Coal mining provides a means for creating wealth and significantly contributes to export earnings, economic activity and employment whilst supporting regional development. For example, the mining sector of Indonesia contributes to the nation’s economy for about 11.54% of total GDP. However, coal mining is one of the most severe disturbances in terrestrial ecosystems. It causes large-scale deforestation and land degradation with complete loss of topsoil. Thus, the removal of the natural vegetation and upper soil horizons for mining exploration hinders the establishment and survival of plant and soil microbial communities. Revegetation of coal mined lands is therefore required to enable the re-use of such resources for other purposes. The establishment of tree species capable of protecting the underlying soil and its micro-fauna and flora is one way of achieving this aim. This study aims to; (i) determine the potential application of stem cutting to propagate K. anthoteca seedlings. (ii) determine the status of arbuscular mycorrhiza fungi (AMF) symbiosis of vegetatively propagated K. anthoteca (iii) evaluate on the field, the effect of compost and pre-inoculation on vegetatively propagated K. anthoteca for re-vegetation of ex-coal mined site in South Sumatra of Indonesia. The design for the field study was the completely randomized design (CRD) in factorial experiment. Four (4) levels of each factor namely; C0 (control), C1 (5 kg of Salvinia natans compost), C2 (5 kg of community/commercial compost) and C3 (2.5 kg each of Community and Salvinia natans composts); M0 (control), M1 (50 spores of Gigaspora margarita mycorrhizae), M2 (50 spores of Glomus manihotis mycorrhizae) and M3 (25 spores each of G. margarita and G. manihotis) mycorrhizae with four replicates. Data collected on plant height, diameter and leave count were subjected to a twoway analysis of variance (ANOVA) at a significance level of 5% (α ≤ 0.05) using the Minitab statistical analysis package (Minitab Inc.). Tukey’s HSD test was used for multiple comparison tests for treatments that differed significantly. Results of the cutting experiment demonstrated that, the species can be vegetatively propagated through cutting without hormone application. Analysis of variance tested at α ≤ 0.05 revealed no significant difference between the treatment means of hormone and wounding on the number of roots. Again, the length of the longest root was not significantly different over the control treatment. The trapping experiment also showed no significant difference between K. anthoteca cuttings and other trapping plant species. However, this observation was frequent in the young and meristematic segments of the roots for K. anthoteca. An average root colonization of 32% was observed for K. anthoteca 4 and the highest recorded by S. bicolor of about 43%. There was also a significant positive correlation (r = 0.892; p ≤ 0.000) between percentage root segment colonization and the number of counted spores. The results for the field experiment showed that compost has significant effect (P < 0.001) on height, diameter and leaf increments with steady increment for the study period. There was no significant effect (P > 0.05) of mycorrhizae treatment as well as the interaction between both factors (AMF and compost) on the growth of K. anthoteca on the field. However, compost composition from a mixture of S. natans and that prepared from the community of PT. Bukit Asam (C3) recorded higher increment in height of 9.31 cm while compost from S. natans only (C1), community compost (C2) and control (C0) had increments of 9.00 cm, 5.78 cm and 4.47 cm respectively. The arbuscular mycorrhizae fungi played major role in the survival of the species on the field. There was significant percentage difference of between 18.5-37.5% over the control treatment. AMF from G. manihotis had the highest plant percentage survival of 81.25% whiles the control had the lowest percentage of 43.75%. The study concludes that wounding treatment play more critical role in the vegetative propagation of K. anthoteca seedlings as compared to hormone (auxin) application. Again, AMF soil inoculums under K. anthoteca can be a good source of inoculants for the establishment of the species in areas of degraded lands. Furthermore, AMF and compost applications are feasible and sound technologies for establishing K. anthoteca on an ex-coal mined site. Plants are also able to withstand harsh environmental conditions through fungi-plant symbiosis enhancing the chances of survival on the field, aiding plant establishment. Thus, K. anthoteca propagules can be established on an ex-coal mined site with compost and AMF inoculation. However compost made from organic materials such as S. natans is preferable for the growth and development of the plants.