No abstract

No abstract

No abstract

No abstract

Soil salinity is a major environmental stress that has been negatively affecting the growth and productivity of rice. However, various salt-resistant plant growth-promoting rhizobacteria (PGPR) have been known to promote plant growth and alleviate the damaging effects of salt stress via mitigating physio-biochemical and molecular characteristics. This study was conducted to examine the salt stress potential of Bacillus strains identified from harsh environments of the Qinghai-Tibetan plateau region of China. The Bacillus strains NMTD17, GBSW22, and FZB42 were screened for their response under different salt stress conditions (1, 4, 7, 9, 11, 13, and 16%). The screening analysis revealed strains NMTD17, GBSW22, and FZB42 to be high-salt tolerant, moderate-salt tolerant, and salt-sensitive, respectively. The NMTD17 strain produced a strong biofilm, followed by GBSW22 and FZB42. The expression of salt stress-related genes in selected strains was also analyzed through qPCR in various salt concentrations. Further, the Bacillus strains were used in pot experiments to study their growth-promoting ability and antioxidant activities at various concentrations (0, 100, 150, and 200 mmol). The analysis of growth-promoting traits in rice exhibited that NMTD17 had a highly significant effect and GSBW22 had a moderately significant effect in comparison with FZB42. The highly resistant strain NMTD17 that stably promoted rice plant growth was further examined for its function in the composition of rhizobacterial communities. The inoculation of NMTD17 increased the relative abundance and richness of rhizobacterial species. These outcomes propose that NMTD17 possesses the potential of PGPR traits, antioxidants enzyme activities, and reshaping the rhizobacterial community that together mitigate the harmful effects of salinity in rice plants.

No abstract

No abstract

Land degradation caused by deforestation seriously affects the soil environmental capacity (SEC), with potential risks to soil health. However, conventional SEC theory is unable to quantitatively describe the saturation capacity of different soil fractions and environmental pollution levels of a heterogeneous system. Thus, a new concept, the soil pool capacity (SPC), was introduced to fill this gap. We undertook space-fortime substitution to investigate the responses of SPCand soil safety capacity (SSC) to changes in the soil physiochemical properties, chemical species, and molecular characteristics of soil lead (Pb) in the conversion of tropical secondary rainforest (TSR) to rubber (Hevea brasiliensis) monoculture plantations with 15-and 60-year histories (RP 15/60). Conversion of TSR to RP 15/60 caused adverse effects on soil properties (i.e., lower soil organic matter [SOM] and higher bulk density [BD]). The saturated SPC (SPC sat) for Pb in bulk soils under RP 15 (2,203.17 g m −2) and RP 60 (1,634.09 g m −2) decreased compared with that in TSR (2,227.10 g m −2). The contribution rates of SPC sat in the exchangeable (P1) and carbonate (P2) pools to the total capacity stabilized at approximately 94%. The contribution rate of potential SPC sat in P4 (OM-bound Pb) significantly decreased with increasing agricultural intensity. The SSC of labile fractions (P1 + P2) accounted for 81-85% (a critical level) of the total SSC when the soil loading capacity for Pb reached the SSC in bulk soil regardless of land-use type. Fourier transform infrared and X-ray diffraction spectra revealed the Pb-loaded species of SPC sat in TSR and RP 15/60 (i.e., TSR: Pb 2 SiO 4 in P2, (CH 3 COO) 2 Pb in P4, RP 15/60 : Pb 5 Si 8 O 21 and Pb 2 (P 4 O 12) in P2, and (CHOO) 2 Pb in P4). Correlation and factor analyzes showed that SOM and BD were key factors that had an opposite impact on SPC sat and SSC. These results are helpful to choose appropriate agronomic measurements to reduce land degradation and crop safety risks caused by deforestation.