基于近红外技术柑橘黄龙病田间快速检测方法研究

柑橘黄龙病在感病植株和健康植株之间传播速度快,因此快速检测柑橘黄龙病对其防治十分关键。本文研究了近红外技术快速检测柑橘黄龙病的方法。采用PLS-LDA建立的模型对未参与建模的样品进行了检测,结果表明,该模型检测的准确率与普通PCR检测的结果符合率达到100%,假阳性率小于1%。该技术具有检测周期短、无污染等优点,可用于田间黄龙病的快速检测。     

Assessment of cytoskeletal damage in Paramecium caudatum: An early warning system for apoptotic studies

The freshwater protozoan ciliate, Paramecium caudatum was used in order to assess the potential cytotoxic effects of fenthion, an organophosphorus insecticide (OPI). It was found that fenthion at concentrations of 76 mg L⁻¹ (LC₅₀ for 2 h) effected cellular morphology of P. caudatum and inhibited its locomotion, as well as degradation of cytoskeleton leading to cell destruction. Cytoskeleton morphology, cytoplasmic components and locomotor behaviour tests were performed by combined conventional light microscopy and a computerized video-tracking system. After short reparation periods from 10 min to 2 h, there was an increase in the number of apoptotic cells with typical features like plasma membrane blebbing, blackening of cytoplasm (due to mixing of the vacuolar contents) and outflow of cytoplasmic contents into blebs leading to cell lysis. The present findings on blackening of cytoplasm, multiple blebs and macronuclear changes indicate a possible apoptotic effect of fenthion on P. caudatum. Development of such simple apoptotic model systems like paramecium with simplicity in handling, low cost, ease in maintenance, rapid performance and high reproducibility provides an ‘early warning system’ for risk assessment in forecasting long-term hazards of pesticides on non-target organisms including humans.     

Influence of dosage,storage time and temperature on efficacy of metalaxyl-treated seed for the control of pearl millet downy mildew

Metalaxyl (Apron 35WS) as a seed treatment has been used extensively to control downy mildew (caused by Sclerospora graminicola) in pearl millet in India. However, the extent of disease control has varied across cultivars, years and locations. We investigated the effects of fungicide dosage, storage time and storage temperature of metalaxyl-treated seed on disease incidence in four pearl millet lines having varying levels of resistance. A linear relationship was found between fungicide dosage (0.5, 1.5 and 2 g a.i. kg⁻¹ seed) and reduction in disease incidence up to 40 days after emergence in all the lines. The normal fungicide dose (2 g a.i. kg⁻¹ seed) protected the crop for up to 20, 40 and 50 days after emergence in highly susceptible (7042S), moderately susceptible (4042R), and moderately resistant (ICMP 451) lines, respectively. However, the quarter and half the normal dosage of fungicide provided protection only up to 20 days after emergence in 7042R and 40 days after emergence in ICMP 451. Storage duration of metalaxyl-treated seed (2 g a.i. kg⁻¹) up to 9 months at 25 ± 2°C did not affect fungicide efficacy. Storage temperatures (5, 25 and 40°C) and duration (30, 60 and 90 days) of metalaxyl-treated seed (2 g a.i. kg⁻¹) showed differential effects in two pearl millet lines 7042S and 843B with downy mildew incidence being significantly lower in 7042S than in 843B. Metalaxyl-treated seed of 7042S and 843B stored at 40°C for different durations showed phytotoxic effects and it was more pronounced in 843B stored for 60 and 90 days where seed germination was inhibited in pot soil.     

Use of gas chromatographic retention indices for quantitative structure activity relationship studies of dialkyl phenyl phosphates

Thirty-five dialkyl phenyl phosphates analogous to methyl and ethyl paraoxon were synthesized and their insecticidal activity against house fly (Musca nebulo) determined. Gas chromatographic retention indices (GCRI) at 200°C for all the phosphates were determined on OV-101, DB-1701 and DB-WX fused-silica capillary columns. The retention indices on polar and nonpolar columns (DB-1701 and OV-101, DB-WX and OV-101) considered together were shown to be related to the Hansch hydrophobic constant (II). Multiple regression analysis using the least-square method was carried out to establish the linear relationships between insecticidal activity and GCRI along with the Hammett constant, (σ). The multiple correlation coefficients (r) of various parameters obtained using GCRI were found to be as significant as those obtained using II values. It was found that both hydrophobic and electronic effects made a significant contribution to the insecticidal activity of dialkyl phenyl phosphates. It is concluded that GCRI on two columns can be used directly as an indicator for hydrophobicity in QSAR studies provided that a suitable pair of polar and nonpolar columns is used for this purpose.     

Evaluation of the effectiveness of a new pheromonic trap for monitoringlasioderma serricorne (F.) in tobacco stores

The “Black Stripe Moth Trap”, a funnel type one (commercially available from AgriSence Inc.) designed for monitoring storage and field moths, was tested in tobacco stores in order to evaluate its effectiveness onLasioderma serricorne. The experiment took place for a 12 months-period (in 1996), in a private warehouse in Thessaloniki, Macedonia, Greece. The trap was applied baited (with 15 mg “serricornin”) and unbaited (control). The pheromonic trap has shown an impressive efficacy in trapping the tobacco beetle adults as it caught ∼95.4% of the total number of the insects, during the whole experimental period.     

Spectrophotometric determination of ziram and zineb using 4-(2-pyridylazo) resorcinol

A spectrophotometric method has been developed for the determination of ziram (zinc bis(dimethyldithiocarbamate)) and zineb (zinc ethylenebisdithiocarbarnate) by converting these into a zinc-4-(2-pyridylazo)resorcinol complex, which is dissolved in acetone and water and the absorbance measured at 490 nm against a reagent blank. Beer's law is obeyed over the concentration ranges 0.025-1.25 and 0.025-1.5 mg litre^?1 for ziram and zineb respectively in the final solution. The method is sensitive and can be used for the direct determination of ziram and zineb in commercial formulations, grains (rice and wheat) and synthetic mixtures (in the presence of various other dithiocarbamates). The limit of determination of ziram and zineb from foodstuffs in 0.2 mg kg ^?1.     

Transport of the systemic fungicide cela W 524 in barley plants (part I)

Doses of 11–20 mg of the title compound in aqueous formulation were added to barley plants in pots. Radioactivity and biological activity against Puccinia coronata on eight different sections of the shoots as well as the inhibition of Cladosporium spore development on thin-layer chromatograms from methanolic extracts were followed during the first 24 h. Transport velocities, distribution and useful doses are discussed.     

Biomass Yield and Essential Oil Yield Variations in Java Citronella (Cymbopogon winterianus Jowitt.), Intercropped with Food Legumes and Vegetables

Java citronella ( Cymbopogon winterianus Jowitt., Family: Poaceae) is a perennial, multiharvest aromatic grass, the shoot biomass of which, on steam distillation, yields an essential oil extensively used in fragrance and flavour industries. It has a long initial lag phase. To utilize the crop resources more efficiently during this lag phase, a field experiment was conducted for two years (1995–97) in semiarid tropical climate to explore the feasibility of intercropping food legumes and vegetables in Java citronella. Among food legumes, greengram ( Vigna radiata (L.) Wilez.), and among vegetables, clusterbean ( Cyamopsis psoraloides D. C., syn. Cyamopsis tetragonoloba (L.) Taub.), tomato ( Lycopersicon esculentum Mill.) and lady's finger ( Abelmoschus esculentus Moench.) as intercrops did not decrease the biomass yield, essential oil yield of Java citronella and produced bonus yields of these crops over and above that of Java citronella. Maximum monetary returns were recorded by Java citronella intercropped with tomato or greengram. Java citronella intercropped with redgram ( Cajanus cajan (L.) Millsp.), horsegram ( Macrotyloma uniflorum (Lam.) Verd. syn. Dolichos biflorus Roxb.) and brinjal ( Solanum melongena L.) suffered significant biomass and essential oil yield reductions. Horsegram proved to be the most competitive intercrop producing least yields and minimum monetary returns.     

Optimizing seed quality during germplasm regeneration inpearl millet

The effect of water stress during flowering and grain filling on seed longevity was studied in three pearl millet genotypes,ICTP-8202, ICTP-8203 and MBH-110. The seeds were produced by three pollination methods; open pollination, selfing(individual panicles enclosed in paper bags), and cluster bagging (panicles from 3–4 adjacent plants enclosed in a paper bag), stored in air-tight plastic bottles underambient conditions (20–40°C,30–80%RH) and germination was tested at 12-month'sintervals. The seeds lost germination completely after six years ofstorage in all treatments. Analysis of variance of the estimates of potential seed longevity (i.e. the seed lot constantK _i of the seed viabilityequation) showed significant effects of water stress andpollination method (P < 0.01). The interaction between irrigation treatment and method of pollination control was also significant (P < 0.05). Averaged over genotypes and pollination methods,potential longevity was greatest(K _i = 2.8) in theirrigated control, and averaged over genotypes and irrigationtreatments, it was greatest (K _i= 3.1) in seeds produced by open pollination. Theimplications of these results were discussed in relation to germplasmseed production.