GROWTH RESPONSE OF NARRA (PTEROCARPUS INDICUS WILLD.) SEEDLINGS TO MICROBIAL BIOFERTILIZER APPLICATIONS IN MINED-OUT SOILS OF PLACER AND CLAVER, SURIGAO DEL NORTE, PHILIPPINES

Abstract

Two concurrent nursery experiments were conducted following a randomized complete block design (RCBD) aimed at screening the effectiveness of arbuscular mycorrhizal fungi (AMF) and nitrogenfixing bacteria (NFB) in promoting growth and survival of narra seedlings grown in Ni and Au mined-out soils. Seedlings were inoculated with either MYKORICH®, MYKOVAM®, newMycorrhiza (newMYC), newNitrogen-fixing bacteria (newNFB) and combined newMYC and newNFB or not inoculated (control). Narra seedlings were inoculated with uniform amounts of microbial biofertilizers and were grown for a month to ensure root infection. After 30 days, the uninoculated (control) and inoculated seedlings were transferred into polybags filled with mined-out soils mixed with compost (1:1; v%/v%) and were applied with 10 g complete (14:14:14NPK) fertilizer per seedling. After six months of observation, results demonstrated notable and significant effects to the incremental growth in height, stem diameter, plant dry weight and root-to-shoot ratio of narra seedlings in response to the applied microbial biofertilizers. MYKORICH®, newMYC, newNFB and the combined newMYC and newNFB are recommended microbial biofertilizers for narra seedlings used for rehabilitating Ni and Au mined-out sites. Furthermore, combined newMYC + newNFB and MYKORICH® yielded the highest quality seedling index while MYKORICH® gave the highest biovolume index, for seedlings grown in both Ni and Au mined-out soils. The assumption that adding NFB to the already NFBloving narra species enhances its capability to absorb more nutrients and adapt in heavy metal contaminated soils was proven in this study which makes it a potential host-plant in the bioremediation and rehabilitation of Ni and Au mined-out areas in Claver and Placer (Surigao del Norte), respectively.