Micronutrients, such as zinc (Zn), are essential for the growth and development of a wide range of crops. To overcome Zn deficiency in the soil, Zn-solubilizing bacteria (ZSB) have recently been employed. In the present study, samples from the rice fields in the state of Selangor, Malaysia, were collected to isolate, characterize, and identify the ZSB. A total of 88 strains were isolated, and only 9 strains were able to solubilize the insoluble Zn on zinc oxide (ZnO)-, zinc carbonate (ZnCO₃)-, and zinc phosphate (Zn₃(PO₄)₂)-amended Tris-minimal media agar and broth assays. The highest Zn solubilization (20.99%) was measured for the TM23 isolate when exposed to Zn₃(PO₄)₂-modified media culture, whereas ZnCO₃ showed the lowest (3.35%) Zn solubilization by ZSB. In addition, nine isolated ZSB also exhibited plant-growth-promoting (PGP) traits, including nitrogen fixation ability, siderophore production, indole acetic acid production (35.28–65.48 mL⁻¹), phosphate solubilization (27.69–77.38%), enzyme hydrolysis, and production of organic acids. Most of the isolated strains (88) were Gram-negative, except for TM54, which was Gram-positive. The four potential ZSB isolates based on 16RS rDNA sequence analysis were identified as Serratia sp. and Acinetobacter sp. Hence, this study’s findings suggest that these isolates could be prospective candidates to overcome Zn deficiencies and reduce the consumption of chemical fertilizers in agricultural areas.

Zinc-solubilizing bacteria (ZSB) can increase zinc bioavailability in soil and transform insoluble zinc into an accessible form, which helps reduce crop zinc deficiencies, simultaneously improving soil fertility and crop nutrition. The effects of two ZSB strains, Acinetobacter nosocomialis (SR R-10) and Acinetobacter seifertii (SR-12) were evaluated in the present study on the rice plant growth and nutrient contents using the bead inoculation method. A completely randomized design (CRD) was employed and four treatments were applied: 1) non-inoculated (control), 2) SR R-10 strain, 3) SR R-12 strain, and 4) mixed inoculation of SR R-10 and SR R-12 strains. After 40 days of sowing, the growth parameters were measured. The results revealed that SR R-10 inoculant enhanced the growth by producing the tallest plant (63.47 ± 1.87 cm) and longest root (19.93 ± 0.48 cm). SR R-10-treated plants also showed the highest leaf count (32 ± 0.58 leaves) and Soil Plant Analysis Development (SPAD) value (32.67 ± 1.59). The mixed inoculant showed synergistic benefits, indicated by the higher plant height, SPAD reading, and leaf count, compared to the non-inoculated treatment. SR R-10 and mixed inoculant increased plant biomass, measuring 4.67 ± 0.30 g and 4.40 ± 0.28 g, respectively, compared to non-inoculated plants (3.19 ± 0.17 g). For nutrient content, plants with SR R-10 inoculation showed the highest concentration of nitrogen (2.24 ± 0.00%), phosphorus (0.24 ± 0.00%), potassium (2.79 ± 0.03%), and zinc (59.51 ± 2.69 mg kg-1). Mixed inoculant also improved soil fertility by increasing the available Zn (6.17 mg kg-1) in the soil, however, it lowered the soil pH to pH 5.8. These findings highlight the potential of ZSB, particularly A. nosocomialis (SR R-10), to improve rice plant’s growth and nutritional quality and increase the bioavailability of zinc in the soil to promote sustainable agricultural practices.

Background: The expected global climate change, in addition to increasing air temperature and CO2 levels, will manifest itself in changes in precipitation and various physical, chemical and biological soil indicators that are responsible for its fertility and productivity. Potential impact of global warming on soil fertility will primarily manifest itself in changes in soil hydrology and temperature. Changes in soil temperature and physicochemical properties due to climate warming ultimately affect crops. Objectives: The current review aims to systematize some of the key advances in the relationship between soil temperature, root development and microbial communities. It is hoped that organizing the results achieved to date will allow other researchers to better understand the existing gaps and continue to advance this field of knowledge to address climate change and its impacts. Because the right choice of future research should contribute to achieving SDG 2 "Zero Hunger" by 2030. Methods: When writing the review, analysis and synthesis were used, mainly of recent scientific publications in the studied field of knowledge, as well as induction and deduction of the information obtained. There were no research restrictions on the type of publication, the country of the authors, the language, or the number of citations. For the review, mainly recent sources no older than 10 years were selected. Results: Microorganisms respond within their limitations when exposed to temperature variations. Different microbial species may have very different soil temperature preferences; and slow temperature variations favour the selection of the fittest species, allowing the microbial community to adapt. The most significant environmental factor affecting the development and activity of microorganisms in soil is temperature in combination with water content. Soil respiration refers to the transfer of CO2 from soil to air, primarily by soil microorganisms and plant roots. The rate of soil respiration decreases exponentially with increasing latitude and increases with increasing temperature. Several field and laboratory studies have shown a positive correlation between soil respiration and temperature. Rising global temperatures are expected to increase the respiration rate of bacteria that break down organic carbon in soils, resulting in a 40% increase in CO2 emissions. Conclusion: In the future, plant and microbial activity variations will be closely related to changes in soil temperature and moisture, and these micro-ecological interactions will be critical in nutrient availability and net ecosystem productivity. Microbes determined to be beneficial are an essential component in maintaining soil quality and paddy production. Despite increasing temperature stress tolerance, heat and cold shocks continue to limit rice output. The physiology of temperature-sensitive root mechanisms in rice and the interaction between shoot and root growth should be better understood to better understand. Because the effects of soil chemical and microbial activity were included in the soil temperature treatments in this study, it was necessary to separate these indirect effects from the direct sensitivity of the root growth process to changes in soil temperature.

Long-Term Biofertilizers and Chemical Fertilizer Use on Selected Peat Soil Properties of Oil Palm Plantation