Long-Term Use of Copper-Containing Fungicide Affects Microbial Properties of Citrus Grove Soils

Abstract

Long-term use of Cu-conraining fungicides in eitrus groves has resulted in Cu buildup in the soil, but the effects of Cu contamination on microbial properties of citrus grove soils remain poorly understood. The objective of this study was to investigate the influence of long-term application of Cu-containing fungicides on microbial biomass, and bacterial community structure and diversity in five representative commercial citrus groves (5, 21, 27, 36, and 43 yr of planting history, respectively) soils, with one adjacent pasture soil as a reference. With increasing planting time of citrus, Cu concentrations in the soils increased, while microbiological properties including microbial biomass carbon (Cmic), microbial quotient (MQ), and the diversity of operational taxonomic units based on denaturing gradient gel electrophoresis (DGGE) community fingerprinting decreased. Stepwise multiple regression analysis showed that Cmic, microbial quotient, and bacterial community diversity were affected by Cu concentration and other soil properties such as total N and available P, but the effect of Cu was dominant.These results indicate that long-term application of Cu-containing fungicides has adverse effects on microbial biomass and bacterial community diversity in citrus grove soils. Sequencing of partial I6S rRNA gene fragments revealed that a shift of total bacterial community composition occurred as a result of Cu contamination, and the soils of more severely Cu-polluted citrus groves were dominated by bacteria g-Protcobacterium, Acldobacteria, Firmicutes, and b-Proteobacterium, whereas certain strains of s-Proteobacterium, g-Proteobacterium, Firmicutes, and Cyanobacteria were the dominant bacteria in the young citrus grove soils.

Accumulation and availability of copper in citrus grove soils as affected by fungicide application

“…Among the tested soils, three (soils 3, 4, 12) exceeded the maximum allowable concentration of Cu (100 mg kg −1 ) for agricultural soils proposed in the USA (Kabata-Pendias and Pendias 2001). The results from a previous study in the same area indicated that Cu accumulation has significantly reduced soil microbial biomass and microbial community diversity in these soils (Zhou et al 2011). Copper accumulation in the soils also accelerated soil acidification as external Cu loading enhanced the replacement of exchangeable H + /Al 3+ on clay minerals and oxides, thus reducing soil pH.…”

“…3). Reduced microbial biomass and microbial community diversity were reported in the high Cu soils (Zhou et al 2011). Therefore, best management practices need to be developed to remediate Cucontaminated soils.…”

“…In sandy acidic soil, Cu concentrations at >100 mg kg −1 caused phytotoxicity to citrus plants and subsequently decreased their productivity (Alva 1993). Copper accumulation has been reported to reduce microbial biomass and diversity in these soils (Zhou et al 2011). Transport of Cu from land to surface waters through surface runoff and/or leaching has been identified as an environmental issue, since Cu concentration as high as 300 mg kg -1 was measured in the sediment of Saint Lucie River in the citrus growing area (Zhang et al 2003c).…”

Copper and herbivory lead to priming and synergism in phytohormones and plant volatiles in the absence of salicylate-jasmonate antagonism

“…Plants can be exposed to high levels of Cu in their above-and belowground parts due to common use as a fungicide and the fact that heavy metals accumulate in soil over time. 7 In our study, experiments were performed with intact Zea mays seedlings as it is a well-established model plant for VOC-mediated interactions. Young maize plants were grown in hydroponic solution at three different Cu levels (0 μM = control, 10 μM = CuL, 80 μM = CuH) for three days and subsequently challenged with 15 second-instar caterpillars of Spodoptera frugiperda.…”

Do convencional ao orgânico: respostas de um manejo de transição em um pomar cítrico

“…Dentre os defensivos agrícolas o mais impactante estão os fungicidas, que também produzem alterações na microbiota do solo conforme seus componentes químicos (ZHOU et al, 2011;CAMPOS et al, 2015;WANG et al, 2016). (CARVALHO, 1999;FABER;DOWNER;MENGE, 2001;BREMER NETO et al, 2008;WANG et al, 2012).…”