Improving banana and oil palm seedlings growth using indigenous nitrogen fixing and phospate solubilizing bacteria

Abstract

Oil palm is the biggest commodity crop while banana is the second largest fruit crop planted in Malaysia. Both are highly nutrient-demanding crops that requires a large amount of fertilizer. This present an opportunity to find alternative source of nutrient that is much cheaper than the imported inorganic fertilizer for oil palm and banana plantation. Hence, the objective of this study was to develop a newly formulated biofertilizer incorporating locally isolated indigenous nitrogen fixing bacteria (NFB) and phosphate solubilising bacteria (PSB) into oil palm empty fruit bunch (EFB) compost as alternative nutrient source for banana and oil palm to improve their growth and nutrient uptake. Three NFB and PSB strains (Enterobacter cloacae, Burkholderia cepacia and Serratia marcescens) were successfully isolated from the root of oil palm and banana to be formulated as biofertilizer for evaluation on oil palm and banana seedlings. The formulated biofertilizer showed high viable cell count of NFB and PSB inoculants in the carrier (fine EFB compost) i.e 2.45 x 108 cfu/g to 4.31 x 109 cfu (colony forming unit)/g carrier was recorded at the second day after inoculation. Biofertilizer formulation containing Enterobacter cloacae showed promising and consistent effect on the growth of oil palm and banana seedlings including increased plant height (13.7% for oil palm and 15.6% for banana), improved total dry biomass production (27.4% and 33.8% respectively) and high total nutrient uptake (nitrogen (N) 30.6-48.1%, phosphorous (P) 27.2-33.1%, potassium (K) 30.5-37.7%, magnesium (Mg) 48.8%, sulfur (S) 18.1-28.5% and boron (B) 24.5%). Enterobacter cloaceae also showed good root colonization ability as shown from the Field emission scanning electron microscopy analysis. The use of nutrient-rich EFB compost (3.06% N, 0.37% P, 4.74% K, 3.32% calcium (Ca), 0.79% Mg, 0.07% S, 70.3 mg/kg B, 102.1 mg/kg copper (Cu), 6600.9 mg/kg iron (Fe), 160.2 mg/kg zinc (Zn), 455.2 mg/kg manganese (Mn) and 41.4% total carbon, C) as carrier for biofertilizer was able to improve the soil properties notably soil pH, organic C, total N, total P, available P and exchangeable Mg. As a conclusion, the application of locally isolated NFB and PSB together with EFB as carrier (as well as source of nutrient) was successful to improve the growth of oil palm and banana seedlings together with the soil properties. Biofertilizer formulation containing Enterobacter cloacae showed higher performance relative to the other formulations, hence recommended to be applied as soil mixture or directly applied into the planting hole of oil palm and banana seedlings during transplanting to the field to encourage the growth and nutrient uptake during early planting phase.