Hormetic UV-C seed treatments for the control of tomato diseases

Hormesis is a dose response phenomenon in which low, non-damaging doses of a stressor bring about a positive response in the organism undergoing treatment. Evidence is provided here that hormetic UV-C treatments of tomato seed can control disease caused by Botrytis cinerea, Fusarium oxysporum f. sp. lycopersici (FOL) and f. sp. radicis-lycopersici (FORL) on tomato (Solanum lycopersicum). Treating seeds with a 4 kJ m⁻² dose of UV-C significantly reduced both the disease incidence and progression of B. cinerea, with approximately 10% reductions in both on cv. Shirley. Disease severity assays for FOL and FORL on cv. Moneymaker showed dose-dependent responses: UV-C treatments of 4 and 6 kJ m⁻² significantly reduced the disease severity scores of FOL, whilst only the 6 kJ m⁻² showed significant reductions for FORL. To determine the effects of treatment on germination and seedling growth, UV-C doses of 4, 8 and 12 kJ m⁻² were performed on cv. Shirley. No negative impacts on germination or seedling growth were observed for any of the treatments. However, the 8 kJ m⁻² treatment showed significant biostimulation, with increases in seedling, root and hypocotyl dry weight of 11.4%, 23.1% and 12.0%, respectively, when compared to the control. Furthermore, significant increases in the root-mass fraction (10.6%) and root:shoot ratio (13.1%) along with a decrease in shoot-mass fraction (2.0%) indicates that the 8 kJ m⁻² treatment stimulated root growth to the greatest extent. There was no effect on hypocotyl and primary root length or the number of lateral roots, indicating no adverse effects to basic root architecture or seedling growth.     

Beneficial effects of glycine on growth and leaf nutrient concentrations of coriander (Coriandrum sativum) plants

Abstract

In this study, the effect of glycine amino acid was evaluated on growth characteristics and nutrient uptake of coriander plants under greenhouse conditions. The treatments were soil application of glycine in two concentrations of 300 and 600?mg kg^?1 soil, foliar application of glycine (in 0.05% concentration), soil application of mix NPK fertilizer and no fertilizer control. The growth parameters of plant height, leaf SPAD value, shoot and root fresh weights were significantly improved by soil application of glycine, particularly in higher concentration. Soil application of glycine also reduced the number of flowered plants, while it increased soluble solids (TSS) and vitamin C of plant leaf extracts than control plants. Leaf nutrient concentrations of nitrogen (N), calcium (Ca), potassium (K), phosphorus (P), iron (Fe), and zinc (Zn), but not magnesium (Mg) and manganese (Mn), were significantly increased by soil application of glycine, whereas soil applied NPK significantly increased P and Ca of leaves than unfertilized control plants.     

不同污染时长土壤中石油烃的生物去除特性及影响因素

利用生物刺激法修复不同污染时长的土壤,比较了向新污染(污染7 d)和陈旧性污染(污染5 a以上)土壤中加入有机肥、有机肥+KNO_3复合物(C∶N=100∶10)、脱硫石膏等处理剂对土壤中石油烃的去除效果。结果表明:对于新污染黄绵土,向土壤中加入有机肥、有机肥+KNO_3对土壤中石油烃去除效果较好,修复150 d时土壤中石油烃去除率分别为60.13%、56.09%;对于陈旧性污染土壤,施入有机肥+KNO_3、脱硫石膏对石油烃去除效果较好,修复150 d时土壤中石油烃的去除率分别为36.62%、36.61%;生物刺激对新污染土壤中石油烃的去除效率高于陈旧性污染土壤。两种不同污染时长土壤中的石油烃生物降解均符合伪一级动力学。生物刺激修复使土壤的pH值由8.50～8.56降低至7.35～7.91。新污染土壤中石油烃的降解率与pH值呈显著负相关(相关系数为-0.789),与微生物数量呈显著正相关(相关系数为0.849);陈旧性污染土壤中石油烃降解率与土壤pH值呈显著负相关(相关系数为-0.683)。研究表明,土壤受到石油污染后立即进行生物刺激修复有利于土壤中石油烃的去除,影响不同污染时长土壤中石油烃生物降解的关键因素并不相同。     

Bioaugmentation and biostimulation effects on PAH dissipation and soil ecotoxicity under controlled conditions

The degradation of spiked anthracene (ANT), pyrene (PYR) and benzo[a]pyrene (B[a]P) in soil (3000 mg ∑ 3 PAHs kg⁻¹ dry soil) was studied in aerobically incubated microcosms for 120 d. The applied treatments aimed at enhancing PAH removal from the heavily contaminated soils are: (i) bioaugmentation by adding aged PAH-contaminated soil (ACS) containing activated indigenous degraders; and (ii) combined bioaugmentation/biostimulation by incorporating sewage sludge compost (SSC) and decaying rice straw (DRS). The adopted treatments produced higher PAH dissipation rates than those observed in unamended PAH-spiked soils, especially for ANT and PYR in the presence of DRS or ACS (>96%). However, B[a]P was the most recalcitrant hydrocarbon to biodegradation. Extracellular enzyme investigation revealed the existence of ligninolytic activities in all soil treatments, including control but no relationship could be found with PAH dissipation. The ecotoxicological assessment indicated that regardless of applied treatment, PAH-spiked soils were chronically lethal to ostracod Heterocypris incongruens and confirmed the sensitivity of the microcrustacean to the concomitant presence of these three hydrocarbons. Lettuce root elongation inhibition was correlated with PAH level but the presence of SSC conferred a strong phytotoxic capacity to PAH-spiked soils. DRS amendment may constitute a cost-effective alternative for hydrocarbon bioremediation as it has impacted positively on soil microbial activity and enhanced PAH removal with no apparent changes in soil physico-chemical properties.     

食细菌线虫和葡萄糖对恶臭假单胞菌去除菲的影响

Bacterial-feeding nematodes can promote the bacterial activity through feeding.Bacterial abundance and their activity affect the degradation of polycyclic aromatic hydrocarbons (PAH) such as phenanthrene.The effects of bacterial-feeding nematodes,bacteria,and their interactions on the degradation of phenanthrene with or without glucose were studied through a microcosm experiment.The results showed that up to 57.0％ of phenanthrene in mineral medium contaminated with phenanthrene was degraded in the control with bacteria alone and bacteria with the presence of nematodes and/or glucose increased the degradation of phenanthrene by 25.6％ to 36.6％.Although both nematode and bacteria abundance decreased gradually,catechol 2,3-dioxygenase (C23O) activity increased during the incubation period.Compared with bacteria alone,the presence of nematodes significantly increased C23O activity as well as the abundance of bacteria;this effect was more pronounced when glucose was present.The results imply that nematodes might promote the removal of phenanthrene from medium by stimulating bacteria and C23O activities.     

生物修复对黄土壤中石油烃的去除作用及影响因素

利用微生物法对石油污染黄土壤进行实验室模拟修复研究,通过测定修复过程中的不同组分烃、不同形态氮和有效磷含量,石油烃降解菌数量对修复效果及影响因素进行了评价。结果发现,经过5周的修复处理,生物刺激法处理的土壤中总石油烃、烷烃、多环芳烃的去除率分别为14.54%、21.98%、33.14%,土壤铵态氮含量由初始添加的210.4 mg·kg-1降低至97.2 mg·kg-1,土壤硝态氮含量在修复过程中基本保持不变。经过生物刺激修复的土壤中石油烃、烷烃、多环芳烃降解菌数分别为1.60×105、3.09×105、7.08×103,而未经修复处理的土壤中三种烃降解菌数量分别为2.69×10~4、2.57×10~4、4.07×103。结果表明利用生物刺激法可有效去除黄土壤中的石油烃。影响石油污染黄土壤生物修复作用的限制性因素为土壤中铵态氮和有效磷含量,与未经修复处理的石油污染土壤相比,生物刺激处理使土壤中烃降解菌数量增加。     

Enhanced bioremediation of PAH-contaminated soil by wheat bran and microbial community response

ABSTRACT

Microcosms were set up containing a PAH polluted soil to investigate biostimulation (addition of wheat bran and fertilizer) and bioaugmentation (inoculation with Pseudomonas sp. SB). After 60 d the fertilizer + wheat bran gave the highest PAH degradation. The degradation rate was 42.2%, significantly higher than the 18.7% in the fertilizer only treatment. Principal coordinate analysis (PCoA) indicates that wheat bran treatment can significantly alter soil bacterial and fungal communities. In addition, wheat bran promoted the enrichment of some soil bacteria such as Bacillaceae, Xanthomonadaceae, Streptomycetaceae, and Chitinophagaceae, and the fungi Talaromyces, Humicola, unclassified_Chaetomiaceae and Mortierella. These results highlight the potential of wheat bran application to reduce the PAHs detected in soil.     

In situ bioremediation of organochlorine‐pesticide‐contaminated microcosm soil and evaluation by gene probe

BACKGROUND: Pesticide‐formulating industries are contaminating the environment through various activities. Bioremediation is the best method for decontamination, as chemical and physical methods are not only costly but also not very effective in open field systems. In the present study, in situ bioremediation of organochlorine‐contaminated soil was demonstrated by combined biostimulation and bioaugmentation strategies, followed by evaluation using a molecular method. RESULTS: Three parameters were monitored: microbial biomass (colony‐forming units (CFU) g^?1 soil), residual pesticides after treatment and catabolic genes from microcosm soil. Both the biostimulation and the bioaugmentation treatments showed an initial lag phase of 80 days towards colony‐forming units. Gas chromatography of soil samples showed that concentrations of residual pesticides in the soil declined by up to 85–90% after 80 days, indicating their utilisation with time. On dot‐blot hybridisation of the total DNA from the same soil samples, it was observed that catabolic genes tfdC (catechol 1,2‐dioxygenase) and cm genes (chlorophenol monoxygenase) were predominant, whereas other catabolic genes such as catechol 2,3‐dioxygenase (xylE) were negligible. CONCLUSION: The strategy of in situ bioremediation and its evaluation by gene probe and also by conventional methods was demonstrated for organochlorine‐pesticide‐contaminated soil in open microcosms. It showed that bioaugmentation along with biostimulation was effective, although initial acclimatisation for a period of almost 2–3 months was required in the open field systems. Copyright © 2009 Society of Chemical Industry