Ultisols fertility and morphological characteristics of N-fixing bacteria from oil palm rhizosphere

Abstract

Exploratory studies on microorganisms from the oil palm rhizosphere can be used to increase the nitrogen availability in acidic soils. The present study aimed to determine the soil nutrients and obtain the relationship among the soil chemical characteristics, as well as the morphological and microscopic characteristics of N-fixing bacteria isolates, in Ultisols from the oil palm rhizosphere. The Ultisols fertility was classified as very low to moderate. In addition, the increasing soil pH toward neutral increased the cation exchange capacity, exchangeable cations (Ca2+, K+ and Mg2+), total N, organic C and available P. Nitrogen-fixing bacteria isolates with varied shapes (circular, concentric, irregular and diffuse) and edges (wavy, slippery and irregular) were found, and the dominant type of isolate presented raised elevation. Four types of isolate had a white color and only one a clear color. Three Gram-positive and two Gram-negative bacteria isolates showed a bacillus shape.

Selectivity of chemical and biological foliar treatments on the phyllosphere communities of bacteria and fungi antagonistic to Fusarium verticillioides in maize

“…These microorganisms were preserved on specific selective media for each type. A similar and homogeneous number of microorganisms was randomly selected from each treatment, based on different physical and morphological characteristics (such as colour and colony morphology) known as “morphotypes” (Oktari et al, 2022). Each fungus and bacterium obtained from the field and stored was assigned a specific designation that allowed us to determine the type of treatment that gave rise to the isolated microorganism.…”

“…These microorganisms were preserved on specific selective media for each type. A similar and homogeneous number of microorganisms was randomly selected from each treatment, based on different physical and morphological characteristics (such as colour and colony morphology) known as "morphotypes" (Oktari et al, 2022).…”