[Effects of Biochar Application on the Structure and Function of Fungal Community in Continuous Cropping Watermelon Soil].

This study was conducted to clarify the long-term effects of biochar application on the structure and function of the fungal community in continuous cropping watermelon soil. Taking watermelon root soil as the research object, Illumina NovaSeq high-throughput sequencing and FUNGuild platform were used to analyze the differences in soil fungal community composition, diversity, and function after 3-year biochar additions of 7.5, 15.0, and 30.0 t·hm-2 and to explore the correlation between soil environmental factors and fungal community structure under the control of biochar. The results showed that compared to that in the absence of biochar (control), the soil pH, available phosphorus, available potassium, total nitrogen, organic matter, and cation exchange capacity increased, but available nitrogen decreased with biochar addition. High-throughput sequencing results showed that biochar amendment improved the fungal community structure in continuous cropping watermelon soil and increased the richness and diversity of soil fungi. A total of 922 OTU were obtained from all soil samples, and the species annotation results indicated that the dominant fungal groups were Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, and Glomeromycota, with these phyla accounting for 85.70 %-92.45 % of the total sequences.The relative abundance of Ascomycota and Basidiomycota decreased, whereas the abundance of Mortierellomycota and Glomeromycota increased with biochar addition.At the genus level, the application of biochar increased the relative abundance of Mortierella and Rhizophlyctis but decreased the abundance of Fusarium. The Mantel test showed that soil available potassium, available nitrogen, organic matter, and pH were the main environmental factors leading to the shift in the soil fungal community composition.The functional prediction with FUNGuild showed that the many nutrient types among the different treatments were saprotrophic, pathotrophic, and symbiotrophic. The relative abundance of pathotrophs significantly decreased, but the abundance of symbiotrophs significantly increased with the medium and high doses of biochar treatment. In conclusion, the application of biochar changed the soil physicochemical properties, promoted the development of soil fungal community structure and functional groups in a healthy and beneficial direction, and improved the quality of continuous cropping watermelon soil.

Effects of root-applied biochar on soil nitrogen transformation and root nitrogen metabolism of cucumber seedlings in facility continuous cropping soils.

The problem of soil barrier caused by excessive accumulation of nitrogen is common in continuous cropping soil of facility agriculture. To investigate the modulating effects of biochar amendment on soil nitrogen transformation in greenhouse continuous cropping systems, we conducted a pot experiment with two treatments, no biochar addition (CK) and 5% biochar addition (mass ratio). We analyzed the effects of biochar addition on soil microbial community structure, abundances of genes functioning in nitrogen cycling, root growth and nitrogen metabolism-related genes expressions of cucumber seedlings. The results showed that biochar addition significantly increased plant height, root dry mass, total root length, root surface area, and root volume of cucumber seedlings. Rhizosphere environment was improved, which enhanced root nitrogen absorption by inducing the up-regulation of genes expressions related to plant nitrogen metabolism. Biochar addition significantly increased soil microbial biomass nitrogen, nitrate nitrogen, and nitrite nitrogen contents. The abundances of bacteria that involved in nitrogen metabolism, including Proteobacteria, Cyanobacteria, and Rhizobiales (soil nitrogen-fixing bacteria), were also significantly improved in the soil. The abundances of genes functioning in soil nitrification and nitrogen assimilation reduction, and the activities of enzymes involved in nitrogen metabolisms such as hydroxylamine dehydrogenase, nitronate monooxygenase, carbonic anhydrase were increased. In summary, biochar addition improved soil physicochemical properties and microbial community, and affected soil nitrogen cycling through promoting nitrification and nitrogen assimilation. Finally, nitrogen adsorption capacity and growth of cucumber plant was increased.

Changes in sulfur in soybean rhizosphere soil and the response of microbial flora in a continuous cropping system mediated by Funneliformis mosseae.

Soybean is an S-loving crop, and continuous cropping might cause soil sulfur shortage. The primary objectives of this study are to determine whether Funneliformis mosseae (F. mosseae) can enhance the content of available S in S-deficient soil and thereby improve the sulfur utilization rate in soybean. The experiment used Heinong 48 (HN48), a soybean variety with a vast planting area in Heilongjiang Province, and F. mosseae was inoculated in the soil of soybean that had been continuously cropped for 0 and 3 years. The results of the barium sulfur turbidimetric assay show that the sulfur content in the soil and soybean was reduced by continuous cropping and increased by inoculation with F. mosseae; the results of the macro-genome sequencing technology, show that the diversity and abundance of bacteria in the soil was decreased by continuous cropping and increased by inoculation with F. mosseae. The sulfur-oxidizing bacteria (SOB) activity and sulfur-related gene expression levels were lower in the continuous crop group compared to the control group and higher in the F.mosseae-inoculated group compared to the control group. Continuous cropping reduced the sulfur content and ratio of soybean rhizosphere soil, affecting soil flora activity and thus soybean growth; F. mosseae inoculation increased the sulfur content of soybean root-perimeter soil and plants, increased the diversity and abundance of rhizosphere soil microorganisms, increased the expression of genes for sulfur transport systems, sulfur metabolism, and other metabolic functions related to elemental sulfur, and increased the species abundance and metabolic vigor of most SOB. In summary, continuous cropping inhibits soil sulfur uptake and utilization in soybean while the inoculation with F. mosseae can significantly improve this situation. This study offers a theoretical research foundation for using AMF as a bio-fungal agent to enhance soil sulfur use. It also supports the decrease of chemical fertilizers, their substitution, and the protection of native soil.

Interactions Between Phenolic Acids and Microorganisms in Rhizospheric Soil From Continuous Cropping of Panax notoginseng.

Large-scale intensive cultivation has made continuous cropping soil sickness more serious for Panax notoginseng in Yunnan. Autotoxic substances can promote the occurrence of continuous cropping soil sickness. Phenolic acids exert a strong autotoxic effect on P. notoginseng. Based on UPLC-MS/MS, the levels of six phenolic acids with the strongest autotoxicity of P. notoginseng rhizospheric soil were tested. Based on Illumina MiSeq high-throughput sequencing technology, the variation in the microbial diversity in the rhizospheric soil was used as an index to explore the interactions between phenolic acids and the soil microorganisms of the P. notoginseng rhizosphere. (1) Continuous P. notoginseng cropping significantly changed the microbial community structure. Continuous cropping increased bacterial Chao1 index and Shannon index and decreased fungal Shannon index. After P. notoginseng disease, bacterial Shannon index reduced and fungal Chao1 index decreased. (2) Phenolic acid significantly changed the bacterial community structure. VA significantly reduced the bacterial Shannon index. Exogenous p-HA, FA, SA, and VA significantly increased the fungal Chao1 index and p-HA showed the most significant effect. Para-HA affected bacterial specificity, and VA affected fungal specificity. (3) VA was positively correlated with most fungi and bacteria. Para-HA was positively correlated with Lelliottia and Flavobacterium. Para-HA was also positively correlated with plant pathogens (Fusarium and Ilyonectria). Para-HA and VA were able to promote the growth of primary pathogenic bacteria. Thus, p-HA and VA are the main phenolic acid-autotoxin substances in P. notoginseng under continuous cropping. (4) A correlation analysis of soil environmental factors associated with fungal and bacterial communities showed that AK, TN, OM, and HN were most strongly correlated with soil microorganisms. (5) The microorganisms in the rhizosphere of 3-year-old soil planted with P. notoginseng exhibited obvious effects on the degradation of the four phenolic acids. The effect of soil microorganisms on phenolic acids was first-order kinetic degradation with a high degradation rate and a half-life of less than 4.5 h. The results showed that phenolic acids could promote the growth of pathogenic bacteria. And the interaction between rhizospheric soil microorganisms and phenolic acids was the main cause of the disturbance of P. notoginseng rhizosphere microflora.

Physiological and transcriptomic analyses to reveal underlying phenolic acid action in consecutive monoculture problem of Polygonatum odoratum.

BACKGROUND: The root rot of fragrant solomonseal (Polygonatum odoratum) has occurred frequently in the traditional P. odoratum cultivating areas in recent years, causing a heavy loss in yield and quality. The phenolic acids in soil, which are the exudates from the P. odoratum root, act as allelochemicals that contribute to the consecutive monoculture problem (CMP) of the medicinal plant. The aim of this study was to get a better understanding of P. odoratum CMP. RESULTS: The phenolic acid contents, the nutrient chemical contents, and the enzyme activities related to the soil nutrient metabolism in the first cropping (FC) soil and continuous cropping (CC) soil were determined, and the differentially expressed genes (DEGs) related to the regulation of the phenolic acids in roots were analyzed. The results showed that five low-molecule-weight phenolic acids were detected both in the CC soil and FC soil, but the phenolic acid contents in the CC soil were significantly higher than those in the FC soil except vanillic acid. The contents of the available nitrogen, available phosphorus, and available potassium in the CC soil were significantly decreased, and the activities of urease and sucrase in the CC soil were significantly decreased. The genomic analysis showed that the phenolic acid anabolism in P. odoratum in the CC soil was promoted. These results indicated that the phenolic acids were accumulated in the CC soil, the nutrient condition in the CC soil deteriorated, and the nitrogen metabolism and sugar catabolism of the CC soil were lowered. Meantime, the anabolism of phenolic acids was increased in the CC plant. CONCLUSIONS: The CC system promoted the phenolic acid anabolism in P. odoratum and made phenolic acids accumulate in the soil.

[Long-term effects of bio-organic fertilizer application on soil organic carbon pool and enzyme activity of cucumber continuous cropping.] / æ–½ç”¨ç”Ÿç‰©æœ‰æœºè‚¥å¯¹é»„ç“œè¿žä½œåœŸå£¤æœ‰æœºç¢³åº“å’Œé ¶æ´»æ€§çš„æŒç»­å½±å“.

The combination of field trial and indoor incubation experiment were conducted to examine the long-term effects of one-time application of bio-organic fertilizer on soil organic carbon (C) components, organic C mineralization, and enzyme activity in cucumber continuous cropping. Compared with CK, bio-organic fertilizer application significantly increased the content of soil organic C, activated C pool, slow-release C pool and inert C pool during four continuous cucumber planting seasons. With the increases of the number of consecutive crops, the proportion of soil inert carbon gradually increased. After four continuous seasons of cucumber planting, the cumulative and daily mineralization rate of soil organic C in the bio-organic fertilizer treatment increased by 17.3%-31.0% and 7.8%-43.0%, respectively. In the stage of cucumber ripening, bio-organic fertilizer application increased the activities of continuous soil urease, catalase, sucrose and neutral phosphatase by 10.5%-62.1%, 4.8%-25.5%, 3.9%-21.4% and 4.6%-66.4%. The activities of those four enzymes increased with the increases of the application amount of organic fertilizer. Results from the correlation and path analysis showed that the activity of the four enzymes were significantly correlated with the dynamics of organic carbon components in soil cucumber continuous cropping process. Soil urease and invertase activities significantly affected organic carbon mineralization during the continuous cropping process of cucumber. Application of bio-organic fertilizer could increase soil organic carbon content and enzyme activity, improve inert carbon ratio of soil organic carbon pools, cumulative and mineralization rate of organic carbon in continuous cropping process, thereby enhance soil carbon sequestration capacity.

[Effects of biochar on soil nutrition and microbial community diversity under continuous cultivated cucumber soils in greenhouse]. / ç”Ÿç‰©ç‚­å¯¹æ¸©å®¤é»„ç“œä¸åŒè¿žä½œå¹´é™åœŸå£¤å »åˆ†å’Œå¾®ç”Ÿç‰©ç¾¤è½å¤šæ ·æ€§çš„å½±å“.

In this study, we examined the effects of biochar addition on the soil nutrition and microbial community diversity in continuous cultivated cucumber soils, using 95% soils of planting cucumbers for 6 and 10 years mixed with 5% biochar as treatment and no biochar addition as control, all plants cultivated in the pots. The results showed that adding biochar increased per plant yield of cucumber by 11.4% and 62.8% compared with continuous cropping soil of 6 years and 10 years, respectively. Biochar addition significantly decreased two continuous cropping soils bulk density, increased the content of soil organic matter, available P content, cation exchange capacity (CEC) and soil pH. Meanwhile, biochar addition remarkably improved the abundance of bacteria, ratio of bacteria/fungi, but reduced the abundance of fungi and fusarium oxysporum, which made fungal type soil turn to bacterial type soil. For 10 years continuous cropping soils of adding biochar, the abundance of soil bacteria and bacteria/fungi ratio were 2.00 and 3.64 times to that in the control, respectively, and the abundance of fungi and fusarium oxysporum were decreased by 54.8% and 55.9%, respectively. Biochar addition significantly enhanced soil microbial activities, soil microbial Shannon and McIntosh indexes of 10 years soil by 1.50, 2.14 and 1.31 times, respectively. For continuous cropping soil of 10 years, biochar addition significantly increased microbial utilization abilities of carbohydrate, amino acid, phenolic acid and amine by 1.62, 1.81, 1.74 and 1.93 times, respectively. There were remarkable influences of soil bulk density, available P content, CEC, and pH value to changes of soil microbial community. In conclusion, biochar addition optimized the riphzosphere environment, increased cucumber yield, and alleviated continuous cropping obstacles by improving soil physical and chemical properties, as well as soil microbial community.

Analysis on Fungal Diversity in Rhizosphere Soil of Continuous Cropping Potato Subjected to Different Furrow-Ridge Mulching Managements.

Knowledge about fungi diversity following different planting patterns could improve our understanding of soil processes and thus help us to develop sustainable management strategies. The objective of this study was to determine the impact of different furrow-ridge mulching techniques on fungal diversity in rhizosphere soil under continuous cropping system. The investigated treatments were: flat plot without mulch (CK); flat plot with mulch (T1); on-ridge planting with full mulch (T2); on-furrow planting with full mulch (T3); on-ridge planting with half mulch (T4); and on-furrow planting with half mulch (T5). NGS (Illumina) methods and ITS1 sequences were used in monitoring fungi diversity of the potato rhizosphere soil. The fungi diversity in the rhizosphere soil was ranked in the order T5 > T2 > T4 > T1 > CK at the early growth stage and T2 > T3 > T1 > T4 > CK at the late growth stage of potato. The fungal communities found in the rhizosphere soil were Ascomycota, Zygomycota, Basidiomycota, Chytridiomycota, and other unidentified fungal communities. Among the fungal community in the rhizosphere soil, Ascomycota was found to be dominant fungi population, with the highest percentage (89%) in the T5 soil whereas the T2 soils had the lowest percentage (67%). The Fusarium abundance in fully-mulched treated soils was higher than in half-mulched treated soil. The dominant genus in the T4 soil was Mortierella, whereas lower populations (1-2%) of Scutellinia, Cryphonectria, Acremonium, and Alternaria were found in that treatment. Among the eumycetes, the dominant fungal class in all treated soils was the Sordariomycetes, which ranged from 57 to 85% in T2 and T5 soils, respectively. The Fusarium percentages in half-mulched treated soils (T4 and T5) were 55 and 28% lower than that of complete mulched treated soils (T2 and T3), respectively. The cluster analysis results showed that, CK, T4, and T5 treated soils and T1, T2, and T3 treated soils had similarities in microbial compositions, respectively. Potato tuber yield was greater under the on-ridge planting with full mulch (T2) treated soil, followed by on-ridge planting with half-mulch (T4) treated soil. The rhizosphere soil under the on-ridge planting with full-mulch (T2) soil had the highest fungal diversity, suggesting that this management was the best environment for fungi, whereas the on-ridge planting with half-mulch (T4) soil had the minimum abundance of Fusarium.

Quantitative Determination of Ferulic Acid Content in Chrysanthemum Morifolium cv. ( Chuju) Continuous Cropping Soil Using Near Infrared Spectroscopy / 分析化学

A near infrared spectroscopy ( NIRS) method was used for rapid quality evaluation of ferulic acid content in chrysanthemum morifolium cv. ( Chuju) continuous cropping soil. Standard leverage, studentized residual and Mahalanobis distance were calculated to eliminate abnormal samples. After the initial near infrared spectrum was treated by two second derivative and Norris smoothing filter noise, 6000-4000 cm-1 wave number range and 7 factors were chosen for partial least squares ( PLS) calibration model. The results showed that good correlation was presented between the calibration set/validation set and the values determined by high performance liquid chromatography, and the calibration correlation coefficient ( Rc ) and validation correlation coefficient ( Rcv ) were 0. 9914 and 0. 9935, respectively. Root mean square error of calibration (RMSEC), root mean square error of validation (RMSEP) and root mean square error of cross-validation (RMSECV) were 0. 484, 0. 539 and 0. 615, respectively. This method was accurate, reliable, simple, rapid and nondestructive, and could be applied to the fast analysis for ferulic acid in continuous cropping soil.