茉莉酸甲酯对烟草抵御棉铃虫的诱导作用

为进一步阐明茉莉酸甲酯（MeJA）诱导植物抗虫的机理,研究了外源MeJA对烟草多酚氧化酶（PPO）、过氧化物酶（POD）、脂氧合酶（LOX）活性及编码氢过氧化物裂解酶（HPL）和蛋白酶抑制剂（PI-I和PI-II）基因表达的诱导作用,并对棉铃虫取食烟草叶片面积及其体重进行了生物学测定。结果表明,用100 μmol/L MeJA处理后,烟草体内PPO、POD和LOX活性显著升高,HPL、PI-I和PI-II表达明显增强,叶片被取食面积减少,棉铃虫体重增加变慢。说明MeJA对诱导烟草抵御棉铃虫有重要作用。     

食品添加剂果胶的研究进展

果胶是以半乳糖醛酸为基本构成单位的高分子多糖,其基本结构分为半乳糖醛酸富集的平滑型区域和中性糖富集的分枝型区域。果胶由于独特的理化性质及多样的生理功能,在食品、化工、医药等领域被广泛应用。对近年来果胶的化学构造特征及其功能特性与应用的研究进展作了较为系统的分析与综述。     

Effect of adjuvants on the rainfastness and performance of tribenuron‐methyl on broad‐leaved weeds

The influence of a non‐ionic surfactant (20% isodecyl alcohol ethoxylate plus 0.7% silicone surfactants), an anionic surfactant (25.5% alkylethersulfate sodium salt), and a vegetable oil (95% natural rapeseed oil with 5% compound emulsifiers) on the performance and rainfastness of a new commercial formulation of tribenuron‐methyl was assessed on four broad‐leaved weeds: wild mustard (Sinapis arvensis), scentless mayweed (Tripleurospermum inodorum), common poppy (Papaver rhoeas), and common lambsquarters (Chenopodium album). In one experiment, six doses of tribenuron‐methyl alone or in a mixture with each of the three adjuvants were applied to each weed species at two different leaf stages. In another experiment, the plants of T. inodorum were sprayed and subsequently subjected to 3 mm of rain at 1, 2, and 4 h after treatment (HAT). The activity of tribenuron‐methyl was significantly enhanced by all the adjuvants on all the weed species and only minor differences were observed among the tested adjuvants. The impact of the adjuvants varied among the weed species and growth stages. The highest response to the inclusion of adjuvants in the spray liquid was found at the late growth stage and on C. album, followed by P. rhoeas and T. inodorum, while S. arvensis was less responsive to the adjuvants. All the adjuvants significantly improved the rainfastness of tribenuron‐methyl on T. inodorum, with differences among the adjuvants being more pronounced when rain occurred shortly after herbicide application. The effect of the vegetable oil on tribenuron‐methyl's rainfastness was significantly lower than that of the surfactants with rain at 1 HAT, while no significant differences among the three adjuvants were observed when rain occurred at 2 and 4 HAT.     

Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns

BACKGROUND: Metam‐sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off‐gassing rate of MITC. RESULTS: Off‐gassing rate was consistently reduced with increasing water seal application. The application of a 2.5–3.8 cm water seal provided significantly lower (71–74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off‐gassing was observed in the 2.5 cm water seal. CONCLUSION: This suggests that volatilization of MITC‐generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench‐scale soil column studies. Copyright © 2010 Society of Chemical Industry     

Effects of reduced‐rate methyl bromide applications under conventional and virtually impermeable plastic film in perennial crop field nurseries

BACKGROUND: Producers of perennial crop nursery stock in California use preplant soil fumigation to meet state phytosanitary requirements. Although methyl bromide (MB) has been phased out in many agricultural industries, it is still the preferred treatment in the perennial nursery industry and is used under Critical Use Exemptions and Quarantine/Preshipment provisions of the Montreal Protocol. The present research was conducted to evaluate reduced‐rate MB applications sealed with conventional and low‐permeability plastic films compared with the primary alternative material. RESULTS: Reduced rates (100–260 kg ha^?1) of MB applied in combination with chloropicrin (Pic) and sealed with a low‐permeability plastic film provided weed and nematode control similar to the industry standard rate of 392 kg ha^?1 MB:Pic (98:2) sealed with high‐density polyethylene (HDPE) film. However, the primary alternative chemical, 1,3‐dichloropropene (1,3‐D), tended to provide slightly lower pest control even on sites with relatively low plant parasitic nematode, soil‐borne pathogen and weed pest pressure. CONCLUSION: If California regulations change to allow the use of low‐permeability films in broadcast fumigant applications, the results of this research suggest that reduced rates of MB in perennial crop nurseries could serve as a bridge strategy until more technically, economically and environmentally acceptable alternatives are developed. Published 2010 by John Wiley & Sons, Ltd.     

Analysis of metsulfuron‐methyl residues in wheat field soil: a comparison of HPLC and bioassay techniques

BACKGROUND: Metsulfuron‐methyl is a low‐application‐rate sulfonylurea herbicide that is widely used to control broad‐leaved weeds in wheat. Owing to its persistent nature, its residues may be present at phytotoxic levels for the next crop in rotation. Therefore, a comparative evaluation of HPLC and bioassay techniques was made for the analysis of this herbicide in wheat field soil. RESULTS: Metsulfuron‐methyl was applied to wheat crop at different rates (4, 8 and 12 AI ha^?1) at 28 days after sowing as a post‐emergence application, and the soil was analysed for metsulfuron‐methyl residues by HPLC and lentil seed bioassay techniques. The bioassay was found to be the more sensitive technique. At the recommended rate of application, 4 g AI ha^?1, the bioassay technique could detect the residue up to 30 days in surface soil, while, with HPLC, residues were not detectable on the 15th day. The half‐lives of metsulfuron‐methyl by HPLC and bioassay were calculated as 6.3–7.8 and 17.5 days respectively. Under field conditions, residues of metsulfuron‐methyl were also detected in subsurface soil by the bioassay technique at trace levels, but were not detected by the solvent extraction/HPLC method. CONCLUSION: Lentil seed bioassay is a more sensitive technique than HPLC. Traces of residues detected in subsurface soil indicated the mobility of metsulfuron‐methyl into lower layers. Copyright © 2009 Society of Chemical Industry     

LJ-VH01型溴甲烷车载汽化装置的研制

LJ-VH01型溴甲烷车载汽化投药装置具有汽化效率高,自动循环、自动测温加温、精确控制投药量、经久耐用、节约能源等性能。实现了常温下熏蒸剂汽化的自动化全过程控制。该装置气密性保温性能好,投药定量准确,汽化高效。不仅能够较好地解决溴甲烷等熏蒸药剂的汽化问题,而且克服了国内现有汽化投药装置的许多不足。而其紧凑的设计方便整体移动或运输。     

Genetics and evidence for an esterase-associated mechanism of resistance to indoxacarb in a field population of diamondback moth (Lepidoptera: Plutellidae)

Bioassays (at generation G2) with a newly collected field population (designated CH3) of Plutella xylostella L. from farmers' fields in the Cameron Highlands, Malaysia, indicated resistance ratios of 813-, 79-, 171-, 498- and 1285-fold for indoxacarb, fipronil, spinosad, deltamethrin and Bacillus thuringiensis toxin Cry1Ac respectively compared with a laboratory susceptible population (Lab-UK). At G2 the field-derived population was divided into two subpopulations: one was selected (G2 to G7) with indoxacarb (indoxa-SEL), while the second was left unselected (UNSEL). A significant reduction in the resistance ratio for each compound was observed in UNSEL at G8. For indoxa-SEL, bioassays at G8 found that selection with indoxacarb gave a resistance ratio of 2594 compared with Lab-UK and of 90 compared with UNSEL. The toxicity of fipronil, spinosad and deltamethrin was not significantly different in indoxa-SEL at G8 compared with G2 but was significantly greater than UNSEL at G8. The toxicity of Cry1Ac was significantly reduced in indoxa-SEL at G8 compared with G2 but was also significantly greater than UNSEL at G8. This suggests that indoxacarb selection maintained resistance to these compounds in the indoxa-SEL population. Synergist studies indicated that resistance to indoxacarb in indoxa-SEL was esterase associated. Logit regression analysis of F1 reciprocal crosses between indoxa-SEL and Lab-UK indicated that resistance to indoxacarb was inherited as an autosomal, incompletely recessive (D(LC) = 0.35) trait. Tests of monogenic inheritance suggested that resistance to indoxacarb was controlled by a single locus.     

Repellent Activity of Extracts of Wild Rice Species against Panonychus citri and Aphis citricola in Associated with Esterase Isoenzyme in Insests

China is one of the eight centers of origin for crop plants in the world and also the origin center of Asian cultivated rice. There are three species of wild rice i.e. Oryza rufipogon, O. officinalis and O. meyeriama in the South of China. Wild rice enjoys the second-class national protection in China due to its high research values and possession of abundant stress resistance genes. Wild rice has developed certain level of resistance against stress due to better genetic characteristics sin…     

Physical, chemical and environmental properties of selected chemical alternatives for the pre-plant use of methyl bromide as soil fumigant

Production and use of methyl bromide, a soil fumigant, are being restricted because of this chemical's deleterious effects on stratospheric ozone concentrations. Several products, some of which are currently used as soil fumigants, are being considered as possible replacements for methyl bromide, alone and in various combinations. Among these, 1,3-dichloropropene, methyl isothiocyanate generators such as metam-sodium, and chloropicrin are currently registered, while others such as methyl iodide and sodium azide are at different stages of the registration process. This review examines physicochemical properties, environmental fate, and metabolism of the various potential methyl bromide replacement products.