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Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To tap the resource of halotolerant biocontrol agents, a bacterial strain B268 was isolated from the rhizosphere of halophyte Casuarina equisetifolia L. It was identified based on the polyphasic taxonomic approach. The viable count method and dural culture method were used to assess the antimicrobial activities. Gene clusters related to the biosynthesis of antimicrobial compounds were predicted with antiSMASH. The influence of salt stress on biocontrol traits of B268 was analyzed by checking both the physiological activities and the gene expression levels of cells grown under NaCl gradient conditions. The effect of B268 on plant salt tolerance was evaluated with cucumber seedlings under hydroponic conditions. According to the results of polyphasic identification, strain B268 represents a novel phylotype of the conspecific Bacillus velezensis group. The NaCl concentration (W/V) for growth was 0-15% with the optimum at 3%. Thirteen gene clusters devoted to antimicrobial production were predicted in B268 genome. Nine phytopathogens tested were antagonized by B268, among which negative growth was detected in Ralstonia pseudosolanacearum treated with B268 for 8 hours, and the inhibition rate to Valsa mali var. mali, Alternaria alternate, Colletotrichum gloeosporioides, Alternaria solani were higher than 60%. The concentration of extracellular siderophore and indole-3-acetic acid reached the highest at 1% and 3% (W/V) NaCl, respectively and the phosphate solubilizing index remained stable on the NaCl gradient plates. The expression of indole-3-acetic acid biosynthesis gene dhaS and phytase coding gene phyC were maximally up-regulated at 1% (W/V) NaCl, and siderophore biosynthesis gene dhbC showed the highest expression at 3% (W/V) NaCl. In the hydroponic condition, cucumber seedlings inoculated with B268 were found to be insensitive to 80 mmol/L NaCl and tolerance to 120 mmol/L NaCl, which was illustrated by an increase of soluble sugar by 46.4% and a decrease of malondialdehyde by 67.2% in leaves. In conclusion, B268 is a halophilic biocontrol bacterium with a broad spectrum of antimicrobial activity and its growth-promoting activities show coupling responses to salt. It is suggested that B268 can be used in the biocontrol of plant pathogens or salt stress, as well as in the bioremediation of salinized soils. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rapid and non-destructive estimation of leaf salt ion concentrations in halophytes can provide valuable information for plant growth monitoring, selection of salt-tolerant plants and soil salinity monitoring. In this study, the canopy reflectance (350-2 500 nm) and the leaf salt ion (K+, Na+, Ca2+, Mg2+) concentration in the halophytes were measured in the Ebinur Lake Protection Zones, Xinjiang, China. Data collected includes hyperspectral data and leaf salt ion data, and the relationships between the leaf ion concentrations and the selected spectral indices were analyzed. K+ sensitive wave bands on the photosynthetic effective radiation area of the 400- 700 nm (photosynthetically available radiation, PAR), and focused on the red and yellow areas without differential transform; The sensitive bands of Na+ are concentrated in the near infrared region of 949- 1 355 nm. Ca2+ sensitive bands were concentrated in the visible red and near-infrared regions of 665-672 and 919-1 283 nm. Mg2+ sensitive bands were mainly concentrated in 384, 651- 669 nm, mainly in the visible red light region. There was a certain correlation with the ultraviolet region band, but the correlation was generally small. The correlation between the original spectrum and K+ and Na+ was relatively high, reaching a significant level. Spectral transformation increased the correlation between the contents of Ca2+ and Mg2+ and the spectrum, so that modeling bands could be selected according to the standard. Spectral transformation could improve the correlation between the content of salt ions and the spectrum. There were 64 samples in total, and the proportion of samples used for modeling and verification was 3:1. R2 and root mean squared error (RMSE) were used as accuracy evaluation criteria. A Geographically Weighted Regression (GWR) model and a back propagation (BP) model were constructed for estimating leaf salt ion concentrations with the spectral transform and the spectral indices as ratio vegetation index (RVI), difference vegetation index (DVI) and normalized difference vegetation index, and achieved a promising accuracy. The GWR estimation was the best in the bands in the red light region selected by the reciprocal logarithm of reciprocal of reflectance. The characteristic bands of Na+ were concentrated in the short-wave infrared region under the spectral transformation, and the two-dimensional vegetation index was concentrated in the near-infrared region, short-wave near-infrared region, yellow, orange and red region. The short-wave infrared band selected under first order of square root for Ca2+ content had the best estimation effect through GWR model. Mg2+ content was best estimated in the characteristic bands in the red light region selected by DVI, but the GWR model was not as accurate as BP model in estimating Mg2+ content. Based on the GWR salt ion model, the estimation of ions with higher content was better, and the accuracy of K+ and Na+ models was better than that of Ca2+ and Mg2+. When the GWR model was used to estimate the salt ion content in plant leaves, the characteristic bands all pointed to red and short-wave infrared bands. The model based on logarithms of reciprocal of reflectance and GWR for estimated K+ produced the superior performance (R2=0.930, RMSE=0.018 mg/kg). The optimal GWR model with the highest R2 and lowest RMSE was estimation model on Na+ (R2=0.984, RMSE=0.041 mg/kg) via processing. For the estimation model on Ca2+, the model produced reasonable outcome using first order of square root of reflectance-GWR strategy. Moreover, compared with BP model, the GWR model had insufficient estimation for Mg2+ whereas DVI scheme contributed to improve accuracy of the BP estimated model. By comparison, the GWR model yielded better results in higher-content ion models. In conclusion, our study showed GWR model was effective for estimating leaf salt ions through vegetation spectral information. Sensitive bands for salt ions were prominent in the red bands and short-wave infrared bands, which were consistent with the response of vegetation spectral mechanism. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To elucidate the seasonal variations in soil salinity and its driving factors, and to explore the effects of planting Suaeda glauca and straw mulching on soil desalination and salinity controlling, a field experiment was conducted in extremely heavy saline soil of coastal areas in Rudong, Jiangsu Province. There were four treatments: control (bare land, CK), planting S. glauca (PS), straw mulching A (at 15 t ⋅ hm-2, SM-A), straw mulching 2A (at 30 t ⋅ hm-2, SM-2A). Climate factors (including rainfall, atmospheric temperature, sunshine duration, and atmospheric evaporation) and soil salinity dynamic changes were determined from May 2014 to May 2015. Results showed that: (1) The seasonal variation of soil salinity was obvious in the bare ground (CK), with the lowest (8.69 g ⋅ kg-1) during June-August and the highest (26.66 g ⋅ kg-1) during September- December. The changes of soil salinity in topsoil (0-20 cm) were more intense than that in sub- topsoil (20-40 cm), with the changes in sub-topsoil having somewhat time lag compared the topsoil. (2) Soil salinity in CK treatment had a significantly linear correlation with the cumulative rainfall and evaporation-precipitation ratio of the fifteen-day before sampling. The results from multi- factor and interphase analysis indicated that the increases of rainfall would promote soil desaliniza tion. The rise of atmospheric temperature could exacerbate soil salt accumulation in surface soil. The interaction between rainfall and atmospheric temperature would have a positive effect on soil salt accumulation. (3) PS treatment did not alter the seasonal variation in soil salinity, but it reduced soil salinity in topsoil. (4) In SM-A and SM-2A treatments, the relationship of soil desalinization rate (%, Y) and treatment time (days, X) was expressed as Logistic curve equation. Moreover, the soil desalination rate was over 95.0% in the topsoil after 90-100 days of straw mulching treatment and was over 92.0% in sub-topsoil after 120 days of straw mulching treatment. The soil salinity in SM-A and SM-2A treatments fluctuated below 0.60 g ⋅ kg-1 and 1.00 g ⋅ kg-1, respectively in topsoil and sub-topsoil. Considering the desalination and economic costs, a suitable amount of straw mulching (such as 15 t ⋅ hm-2) before rainy season was recommended, which would promote the soil desalinization and reclamation in extremely heavy saline soil of coastal areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, more and more serious soil salinization is one of the main environmental factors that limit plant growth and crop yield. Many halophilous plants often grow in the saline-alkaline land. In order to better understand the salt tolerant mechanism of halophytic plants, this paper mainly explored some physiological characteristics of the halophytic plant Kalidium foliatum to salt stress according to some physiological indexes. The halophyte K. foliatum is a kind of very salt-tolerant shrub belonging to Chenopodiaceae with high succulence and grows commonly in saline and alkaline arid-desert regions in Xinjiang. Some physiological parameters were detected including the contents of Na+, K+, Ca2+ and proline,the water potential of plant leaf tissue, the content of membrane lipid peroxidation (MDA) and phenotype observation; gene expression of KfP5CS, encoding protein(pyrroline-5-carboxylate synthetase) as a key enzyme catalyzing to synthesize proline by semi-quantitative RT-PCR were assayed to salt stress. The results were as follows: (1) Na+ could accumulate significantly in succulent leaves and roots of K. foliatum, and even the content of Na+ in leaves was more than roots; (2) With increasing salt concentration, the content of proline and the gene expression of KfP5CS were enhanced significantly under salt stress conditions; (3) Na+ and proline as plant effective osmotic regulators, could make the plant cells be still able to absorb water at low water potential from the highly concentrated salt solution, extracellularly; (4) Under 0 and 700 mmol•L-1 NaCl treatments, the contents of MDA in the leaves of K. foliatum were higher than other salt treatments, suggesting that the plants might be subjected to oxidative stress under the both treatments. This phenomenon indicated that the growth environments with the both treatments might be adverse for the plants; (5) From the growth phenotype to salt stress, the biomass of K. foliatum was more under low salt treatments, and the plant growth was better and stronger, indicating the low salt environment seemed to be beneficial to the K. foliatum growth. In summary, the results of the investigation of the K. foliatum plant growth in wild grown environment and under long-term salt stress in our lab showed that it was necessary for the good growth of K. foliatum in a certain salt concentration condition. A relative low salt concentration environment is very optimal for the growth of some very salt-tolerant halophytes like K. foliatum. However, we can also speculate neither salt nor high concentration salt conditions is the stressed environment for the K. foliatum plant growth. The study could provide primary reference for understanding the salt tolerance of K. foliatum and it is also very promising to improve salt tolerance in crops and woods by making use of gene resources of this species and the halophyte K. foliatum could be also used to ameliorate saline-alkaline land by reducing the salt content of soil. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By means of Enzyme Linked Immunosorhent Assay (ELISA), this paper analyzed the contents of endogenous hormones ABA, IAA, ZR, and GA3 in Reaumuria trigyna and its related congener R. soongorica from four different salt habitats. In the identical habitats, the contents of growth-promoting hormones IAA, ZR, and GA3 in R. trigyna were lower than those in R. soongorica, while the content of growth-suppressing hormone ABA was in contrary, which could be one of the main reasons that R. trigyna had a weaker ecological adaptability than R. soongorica. The (IAA+ZR+GA3) /ABA in wild R. trigyna varied with habitats, being saline soil > non-salinized soil > heavy solonchack, which was consistent with the density and coverage of R. trigyna population being the largest on saline soil and followed by on non-salinized soil and heavy solonchack, and suggested that R. trigyna having lived in saline habitat for a long time developed a corresponding inherent adaptation mechanism, and that the integrative regulation of endogenous hormones under salt stress played a key role for the growth and development of R. trigyna. [ABSTRACT FROM AUTHOR]

Soil enzymes play key roles in the construction and succession of coastal wetland communities, while the driving mechanism of their activities under water and salt stress conditions is still unclear. The activities and distributions of sucrase, phosphatase, catalase, and urease in the rhizosphere and non-rhizosphere soils of Suaeda salsa , Phragmites australis , and Tamarix chinensis communities were studied in the Yellow River Delta. Moreover, the changes in soil enzyme activities and their influencing factors during the succession of halophytic plant communities were discussed in combination with changes in the physicochemical properties of soil. The results showed significantly higher soil enzyme activities and soil fertility parameters in the rhizosphere soils of S. salsa , P. australis , and T. chinensis communities than those in the non-rhizosphere soils ( P <0.05). In the rhizosphere soils, the activities of phosphatase and catalase increased in the order of S. salsa < P. australis < T. chinensis , while they increased in the order of T. chinensis < S. salsa < P. australis for sucrase activity, and S. salsa < T. chinensis < P. australis for urease activity. Further, significant differences were found in the physicochemical properties of rhizosphere soils between different halophyte communities ( P <0.05), which indicated that plant types and their rhizosphere effects could affect soil enzyme activities and fertility characteristics. Furthermore, a two-way analysis of variance showed that the rhizosphere effect was greater than that of vegetation type. The soil sucrase activity was significantly positively correlated with available potassium (AK), available phosphorus (AP), and ammonium nitrogen (NH 4 + -N) ( P <0.05). Meanwhile, urease activity was significantly positively correlated with total nitrogen (TN), organic matter (SOM), AK, AP, NH 4 + -N, and nitrate nitrogen (NO 3 - -N) ( P <0.01). Both of the two enzymes were negatively correlated with soil electrical conductivity (EC) ( P <0.01). The phosphatase and catalase activities were found to be significantly positively correlated with soil water content (MC), total carbon (TC), TN, total phosphorus (TP), SOM, AK, and NH 4 + -N ( P <0.05). Additionally, parameters of pH, total potassium (TK), and NO 3 - -N were also significantly associated with catalase activity. Finally, the redundancy analysis (RDA) revealed that main factors affecting the overall soil enzyme activity were TC ( P <0.01), SOM ( P <0.01), MC ( P <0.01), TN ( P <0.05), NH 4 + -N ( P <0.05), and EC ( P <0.05). The findings suggested that soil fertility, water, and salinity are the most influential factors of soil enzyme activity in different halophytic plant communities of the Yellow River Delta.

To elucidate the seasonal variations in soil salinity and its driving factors, and to explore the effects of planting Suaeda glauca and straw mulching on soil desalination and salinity controlling, a field experiment was conducted in extremely heavy saline soil of coastal areas in Rudong, Jiangsu Province. There were four treatments: control (bare land, CK), planting S. glauca (PS), straw mulching A (at 15 t·hm -2 , SM-A), straw mulching 2A (at 30 t·hm -2 , SM-2A). Climate factors (including rainfall, atmospheric temperature, sunshine duration, and atmospheric evaporation) and soil salinity dynamic changes were determined from May 2014 to May 2015. Results showed that: (1) The seasonal variation of soil salinity was obvious in the bare ground (CK), with the lowest (8.69 g·kg -1 ) during June-August and the highest (26.66 g·kg -1 ) during September-December. The changes of soil salinity in topsoil (0-20 cm) were more intense than that in sub-topsoil (20-40 cm), with the changes in sub-topsoil having somewhat time lag compared the topsoil. (2) Soil salinity in CK treatment had a significantly linear correlation with the cumulative rainfall and evaporation-precipitation ratio of the fifteen-day before sampling. The results from multifactor and interphase analysis indicated that the increases of rainfall would promote soil desalinization. The rise of atmospheric temperature could exacerbate soil salt accumulation in surface soil. The interaction between rainfall and atmospheric temperature would have a positive effect on soil salt accumulation. (3) PS treatment did not alter the seasonal variation in soil salinity, but it reduced soil salinity in topsoil. (4) In SM-A and SM-2A treatments, the relationship of soil desalinization rate (%, Y) and treatment time (days, X) was expressed as Logistic curve equation. Moreover, the soil desalination rate was over 95.0% in the topsoil after 90-100 days of straw mul-ching treatment and was over 92.0% in sub-topsoil after 120 days of straw mulching treatment. The soil salinity in SM-A and SM-2A treatments fluctuated below 0.60 g·kg -1 and 1.00 g·kg -1 , respectively in topsoil and sub-topsoil. Considering the desalination and economic costs, a suitable amount of straw mulching (such as 15 t·hm -2 ) before rainy season was recommended, which would promote the soil desalinization and reclamation in extremely heavy saline soil of coastal areas.