Impact of sterilization and chemical fertilizer on the microbiota of oil palm seedlings

Abstract

Soil nutrients and microbiota are known as essential components for healthy plant growth and crop productivity. However, limited studies have been conducted on the importance of soil microbiota in the early growth of oil palm seedlings (Elaeis guineensis Jacq.) under the influence of nitrogen, phosphorus and potassium (NPK) compound fertilizer (nitrogen, phosphorus, and potassium). In this study, we analyzed the root microbial community associated with seedlings grown under normal and sterilized soil conditions to ascertain the microbial strains potentially associated with soil, plant health and chemical fertilizer efficiency. Oil palm seedlings were grown under four treatments: (i) fertilized normal soil (+FN), (ii) unfertilized normal soil (−FN), (iii) fertilized sterilized soil (+FS) and (iv) unfertilized sterilized soil (−FS). Our findings revealed that chemical fertilizer promoted the growth of the copiotrophs Pseudomonadota and Bacteroidota in the control +FN, which are known to degrade complex polysaccharides. After autoclaving, the soil macronutrient content did not change, but soil sterilization reduced microbial diversity in the +FS and −FS treatments and altered the soil microbiota composition. Sterilized soil with a depleted microbial population adversely affected crop growth, which was exacerbated by fertilizer use. In the rhizosphere and rhizoplane compartments, a total of 412 and 868 amplicon sequence variances (ASVs) were found depleted in the +FS and −FS treatments, respectively. Several genera were identified in the ASVs with diminished abundance, including Humibacter, Microbacterium, Mycobacterium, 1921-2, HSB OF53-F07, Mucilaginibacter, Bacillus, Paenibacillus, and several unclassified genera, suggesting their possible roles in promoting the plant growth of oil palm seedlings. Soil sterilization might remove these beneficial microbes from the bulk soil pool, affecting the colonization ability in the rhizocompartments as well as their role in nutrient transformation. Therefore, this study provides useful insights concerning the benefits of a soil microbiome survey before making fertilizer recommendations.

Unveiling changes in rhizosphere‐associated bacteria linked to the genotype and water stress in quinoa

“…As illustrated in Figure S1B, each infusion was divided into two equal volumes, on the one hand, the MB infusion contained microorganisms and nutrients from the soil, and on the other hand, the E infusion was sterilized in an autoclave for 30 min at 121°C (15 psi). In this regard, previous works have shown that the sterilization process does not change the overall macronutrient availability (Ding et al, 2023), and thus the E infusions only contained nutrients from the soil after being sterilized (Autester ST, P. Selecta, Spain autoclave). To ensure that the E infusions did not contain bacteria, 1 mL of each E infusion was plated ('Plate Count Agar (PCA)', 2011) and incubated at 28°C for 7 days to check bacteria growth.…”