Improved Growth Performance of Elaeis guineensis Jacq. Through the Applications of Arbuscular Mycorrhizal (AM) Fungi and Endophytic Bacteria.

Agrochemical application in the oil palm industry has been estimated to be the largest component amounting to almost 30% of the operational costing. Therefore, there is a huge pressure in the oil palm cultivation to exercise sustainable practices, preferably using cheaper alternatives such as biofertilizers and organic substrates. This study investigates the effect of arbuscular mycorrhizal (AM) fungi and endophytic bacteria applied independently and in combination on oil palm growth and nutrient uptake. Greenhouse and field studies were conducted with plant responses assessed through growth parameters. Greenhouse plants were significantly stimulated by AM fungi, Rhizophagus intraradices UT126 (M1), through single microbe application. An increase of 36% in leaf area was noted in M1 plants while the calcium (Ca) uptake in leaves increased by 11%. There was no significant improvement in overall nitrogen, phosphate, and potassium (NPK) uptake but a significant improvement of Ca measurement in greenhouse and field was observed in the leaves. The predicted synergism between mixed inocula of M1 and R. clarus BR152B (M2) on vegetative growth was not observed, suggesting the probability of interspecies incompatibility that requires further investigation. Growth readings in plants treated with the combination of M1-M2 and Pseudomonas aeruginosa UPMP3 in the field were highest without a significant difference as compared to single application of M1. The difference in readings for field and greenhouse may have been influenced by other external factors such as soil type, rhizospheric microbial community, and climate, and therefore requires further elucidation. These findings suggest R. intraradices UT126 as a promising biostimulant candidate in sustainable agronomic practices especially in the nursery practices.