Screening for P- and K-solubilizing, and siderophore producing capacity of rhizobacteria from Khao Dawk Mali 105 Aromatic Rice

Abstract

Low nutrient status and high salinity have been identified as significant constraints for KDML105 aromatic rice production in the TKR region, Northeastern, Thailand. The use of PGPR can provides green alternatives to synthetic fertilizer in this region. In this study, therefore, rhizobacteria were isolated from KDML105 rice and evaluated for their potential in P and K solubilization, and siderophore production. The results indicated that 52.0, 21.5, 17.9, and 21.1% of 629 tested isolates, were able to solubilize P, K-mica, K-feldspar, and produce siderophore, respectively. At 0% NaCl the highest amount of solubilized P (35.6 mg L-1), K (49.5 mg L-1), and hydroxamate-type siderophore (618.3 μg L-1), were obtained from isolates ORF4-13, ORF15-23, and CRF16-3, respectively. Under salt stress, the amount of solubilized P of almost all the isolates increased with salt concentration up to 0.5% NaCl and declined thereafter, as compared to the control. In contrast, the amount of solubilized K progressively decreased with NaCl concentration. On the average, ORF15-23 exhibited promising ability in P and K solubilization under salt stress. The promising isolates obtained in this study should be evaluated for their effects on rice nutrients uptake and growth before developing them as biofertilizer.

Enhancement of the Aroma Compound 2-Acetyl-1-pyrroline in Thai Jasmine Rice (Oryza sativa) by Rhizobacteria under Salt Stress

“…Nine PGPR were isolated from the rhizospheric soil of Thai jasmine rice (Oryza sativa) KDML105 using a conventional serial dilution and plating technique on nutrient agar. These isolates exhibited different levels of phosphate and potassium solubilization, as well as siderophore production, determined in a previous study [45] (Table 1). Quantitative determination of solubilized P and K was performed using a spectrophotometer and atomic absorption spectrophotometer, respectively.…”

“…Quantitative determination of solubilized P and K was performed using a spectrophotometer and atomic absorption spectrophotometer, respectively. Siderophore type was determined by ferric perchlorate assay for hydroxamate type and Arnow assay for catecholate type [45]. Rhizobacterial isolates were obtained from either organic rice farming (ORF) or conventional rice farming (CRF).…”

“…To the best of our knowledge, the use of 2AP-producing ST-PGPR for enhancing the aromatic quality of KDML105 rice has not been studied. In the present investigation, the previously screened PGPR isolates capable of solubilizing phosphate and potassium, as well as producing siderophore [45], were selected to investigate their 2AP production in the culture broth. All isolates were then used to inoculate Oryza sativa KDML105 rice seedlings to evaluate their potential to promote the production of a major aromatic compound, 2AP, in the seedlings under salt stress.…”

Isolation and Characterization of Potential Potassium Solubilizing Bacteria with Various Plant Growth Promoting Traits

“…The amount of potassium released was interpolated as 7.29 and 8.66 mg/L after 10 days of incubation respectively. A study has shown that bacterial isolates could show quantitative estimation of potassium by solubilizing the 13.71 to 23.88 mg L -1 of potassium mineral in liquid Aleksandrov broth medium 24 . The 16S rRNA sequencing of bacterial isolate HPY10 was carried out from National Collection of Industrial Microorganisms, CSIR-National Chemical Laboratory, Pune, India.…”

Rhizoactinobacteria Enhance Growth and Antioxidant Activity in Thai Jasmine Rice (Oryza sativa) KDML105 Seedlings under Salt Stress

“…However, some groups of rhizosphere microbes, particularly salt-tolerant PGPR (ST-PGPR), can survive in high-salt environments due to their ability to cope with osmotic stress; such microbes can improve plant growth as well as plant tolerance to salinity. The protective activities of ST-PGPR are related to their ability to acquire nutrients from the soil, to produce phytohormones and osmoprotectants, and to induce systemic resistance (ISR) [6,7]. Thus, these defense mechanisms could be very helpful for plants in severely saline conditions and promote plant growth under normal and stressful environmental conditions.…”