Low nitrogen content in soil is usually overcome by chemical fertilization. After long application period, high-dose and intensive use of N fertilizers can cause ammonia volatilization and nitrates accumulation in soil. In sustainable agriculture, the use of bacterial inoculant integrated with nutrient management system has a role in soil health and productivity. Azotobacter-based biofertilizer is suggested as a chemical nitrogen fertilizer substitute or addition in crop production to improve available nutrients in the soil, provide some metabolites during plant growth, and minimize fertilizer doses. The objective of this literature reviewed paper is to discuss the role of Azotobacter in agriculture; and the prospective of Azotobacter to increase yield and substitute the chemical fertilizer in food crops production. The results revealed that mechanisms by Azotobacter in plant growth enhancement are as biofertilizer, biostimulant, and bioprotectant. Nitrogen fixation by Azotobacter is the mechanism to provide available nitrogen for uptake by roots. Azotobacter stimulates plant growth through phytohormones synthesis; indole acetic acid, cytokinins, and gibberellins are detected in the liquid culture of Azotobacter. An indirect effect of Azotobacter is exopolysaccharide production and plant protection. Inoculation of Azotobacter in the field integrated with organic matter and reduced chemical fertilizer are reported to improve plant growth and yield.

No-choice feeding tests using ethanol, chloroform, and acetone extractives of teak (Tectona grandis) heartwood clearly showed feeding deterrent activity and toxicity to the subterranean termite Reticulitermes speratus. The amount of 2-methylanthraquinone (MAQ) in teak wood extractives was not related to the feeding deterrents or toxicity, as shown by the no-choice feeding tests conducted using crude extractives containing various amounts of MAQ, MAQ alone, and fractions of crude extractives. As a native pest, the subterranean termite Coptotermes formosanus was more tolerant to the fractions of crude extractives than Reticulitermes speratus, and the mortality observed in C. formosanus was not due to the presence of MAQ.

Illegal gold mining and the resulting gold mine tailing ponds on Buru Island in Maluku, Indonesia have increased Mercury (Hg) levels in agricultural soil and caused massive environmental damage. High levels of Hg in soil lowers plant productivity and threatens the equilibrium of the food web. One possible method of handling Hg-contaminated soils is through bioremediation, which could eliminate Hg from the rhizosphere (root zone). In this study, indigenous fungi isolated from Hg-contaminated soil exhibited Hg-resistance in vitro. Soil samples were collected from the rhizosphere of pioneer plants which grew naturally in areas contaminated with gold mine tailing. The fungi’s capacity for Hg-resistance was confirmed by their better growth in chloramphenicol-boosted potato dextrose agar media which contained various HgCl₂ concentrations. Four isolates exhibited resistance of up to 25 mg kg⁻¹ of Hg, and in an experiment with young Chinese cabbage (Brassica rapa L.) test plants, two fungi species (including Aspergillus) were demonstrated to increase the soil’s availability of Hg. The results suggest that Hg-resistant indigenous fungi can mobilize mercury in the soil and serve as potential bioremediation agents for contaminated agricultural land.

Belitung Island, situated in the Southeast Asian tin belt, experiences substantial transformations in land use and land cover (LULC) driven by mining activities, impacting both local economic growth and the ecosystem. This study aims to elucidate the dynamic LULC changes on Belitung Island and evaluate deforestation trends. LULC data spanning from 1990 to 2020 were acquired from The Indonesian Ministry of Environment and Forestry (KLHK), employing supervised classification of satellite imageries. The dataset demonstrated an overall accuracy ranging from 0.79 to 0.92 and was reclassified into six types based on the Intergovernmental Panel on Climate Change or IPCC's classes, encompassing forest, cropland, grassland, other land, settlements, and wetlands. Our research unveiled a notable reduction of over 25 % in forest cover within the past 30 years. Notably, 2020 exhibited instances of reforestation, which subsequently transformed into cropland (0.57 %), grassland (0.32 %), and other lands (0.39 %). Belitung Island grapples with challenges related to sustainable development, environmental conservation, and food security. Forest Landscape Restoration (FLR) emerges as a potential strategy to address some of the socioeconomic and ecological issues.

We found that decayed wood stakes with no termite damage collected from a termite-infested field exhibited a deterrent effect against the termite Reticulitermes speratus, Kolbe, 1885. The effect was observed to be lost or reduced by drying. After identification, it was found that the decayed stakes were infected by brown rot fungus Fibroporia radiculosa (Peck) Parmasto, 1968. In a no-choice feeding test, wood blocks decayed by this fungus under laboratory condition deterred R. speratus feeding and n-hexane extract from the decayed stake and blocks induced termite mortality. These data provided an insight into the interaction between wood-rot fungi and wood-feeding termites.

Ethylene Inhibition Using 1-Methylcyclopropene and Future Perspective for Tropical Ornamental Plants