THE EFFECT OF BACTERIAL ISOLATES FROM THE RHIZOSPHERE OF IRON SAND PLANTS ON THE GROWTH OF CHILLI SEEDLINGS (Capsicum annuum L.) USING THE AXENIC SAND CULTURE ASSAY METHOD

Abstract

Iron sand soil has low organic matter and high iron (38–59%), making it less fertile for plant growth. Chili plants (Capsicum annuum L.) are tolerant to harsh environments, and the use of Plant Growth Promoting Rhizobacteria (PGPR) can enhance their growth on such marginal land by improving nutrient absorption. This study aimed to test the potential of bacterial isolates PT4C5, KT6A5, and CT4A7 as PGPR, evaluate their ability to increase chili seed germination and plant growth using an axenic sand culture assay, and identify their phenotypic characteristics. The research consisted of survey and experimental methods. The experiment used a Completely Randomized Design (CRD) with five treatments: control (sterile distilled water), isolates PT4C5, KT6A5, CT4A7, consortium, and EM4, each with three replications. Results showed that isolates PT4C5, KT6A5, and CT4A7 exhibited PGPR traits by fixing nitrogen, solubilizing phosphate and potassium, producing indole-3-acetic acid (IAA), and siderophores. The isolates, especially the consortium, significantly increased chili seed germination percentage and improved vegetative growth, including plant height, root length, wet weight, number of leaves, and chlorophyll content. Based on phenotypic characterization, isolates PT4C5, KT6A5, and CT4A7 were identified as belonging to the genus Planococcus.