Interactive effect of arbuscular mycorrhizal fungi (AMF) and transplanting media improves early growth, physiological traits, and soil nutrient status of coconut 'Bido' under tropical monsoon climate

Support for the development of sustainable coconut (Cocos nucifera L.) plantations is important. The ability of arbuscular mycorrhizal fungi (AMF) to enhance plant growth has long been recognized. However, AMF's role in transplanting media for the early growth of coconut is not well researched. The purpose of this study was to investigate the effects of AMF and various transplanting media on plant growth and soil nutrient status. A factorial randomized block design was used, with a three levels dose of AMF inoculum as the initial factor. The second factor was the composition of the transplanting media, specifically the combination of manure (PK), sawdust (SG) and sand (P) at three different levels. The research was conducted in North Maluku, Indonesia, from 2019 to 2022. The measured plant attributes were plant growth from 6 to 30 m after planting (MAT), some physiology traits, and soil nutrient status. The results indicated that the combination of 4 g AMF inoculum seedlin[g.sup.1] with media composition of PK: SG:P = 1/3:1/3:2/3 has resulted in significant improvement (p < 0.01) in stem circumference, leaf midribs number, leaf midribs length, plant height and availability of soil nutrients in terms of N (214.2%), P (78.5%), and K (88.9%). The activity of leaf nitrate reductase also increased significantly (p < 0.01) by 79.5%, as well as chlorophyll a (p < 0.01) and total chlorophyll content (p < 0.01) which increased by 40.6% and 49.1% respectively. The combination of AMF inoculation and transplanting media represent a sustainable agronomic technology that can enhance the optimal nutritional status and promote the early growth of coconut palms. Key words: AMF inoculation, coconut, growth, physiology, nutrient status, transplanting media.