Gas Fumigation Research Articles

Preliminary Tests of Tomato Plant Protection Method with Ozone Gas Fumigation Supported with Hydrogen Peroxide Solution and Its Effect on Some Fruit Parameters

The aim of this research was to determine the impact of hydrogen peroxide spraying and ozone gas fumigation during the growing season of tomato plants grown under cover on the mechanical and chemical parameters of fruit harvested from these plants. Tomato plants were grown under cover in accordance with the principles of good agricultural practice in the soil and climatic conditions of southeastern Poland. During the growing season, tomato fruits were collected for testing in order to determine the impact of the applied variable factors on the modification of selected metabolic pathways of bioactive compounds. As part of the tests on the chemical properties of the fruits, the content of ascorbic acid, the total content of polyphenols, and the antioxidant potential were determined. Additionally, the influence of the tested variable factors on the mechanical properties of tomato fruits was determined. In the case of the total polyphenol content, the most beneficial effects were observed for fruits collected from plants treated with ozonation at a dose of 2 ppm for 3 min and spraying the plants with 1% hydrogen peroxide. The highest antioxidant potential was recorded for fruits of the variants ozonated with doses of 2 ppm for 1 min, 2 ppm for 1.5 min, and 2 ppm for 3 min compared to the remaining variants and controls. In turn, the vitamin C content increased significantly in the tested fruits after the ozonation of plants with a dose of 2 ppm for 1 min and ozonation with a dose of 2 ppm for 3 min combined with spraying plants with 3% hydrogen peroxide. In the case of the mechanical properties of tomato fruits, only the ozonation dose of 2 ppm for 3 min significantly improved them.

Yeast Solution Spray and Ozone Gas Fumigation as Methods of Protecting Tomato Plants Against Diseases

Abstract The aim of the study was to determine the effect of ozone fumigation and spraying with microorganisms, i.e. yeast, on selected physiological parameters, and the extent of disease infection of tomato plants. Tomato plants were grown in the ground under covers. Throughout the 2021 and 2022 growing season, the plants were exposed to variable factors, i.e. fumigation with gaseous ozone at a dose of 2 ppm for 1 minute and spraying with yeast. After ozonation and spraying with yeast, physiological measurements were made on tomato plants, such as: selected parameters of chlorophyll fluorescence (maximum quantum yield of PSII photochemistry, maximum quantum yield of primary photochemistry) and gas exchange parameters (transpiration rate, stomatal conductivity and intercellular CO2 concentration). In addition, the content of chlorophyll using the SPAD method as well as plant infection by diseases was determined. Compared to the control sample, ozonation resulted in a slight decrease in the physiological parameters of tomato plants. In addition, no visible leaf damage was observed after the ozone gas fumigation process. However, the use of microorganisms did not significantly change the examined physiological parameters. Both after the application of gaseous ozone and microorganisms, a significant impact of the tested variable factors was found on reducing the infection of tomato plants by diseases such as: tomato late blight, tomato alter-nariosis, gray mold, bacterial canker of tomato and bacterial spot of tomato.

Effects of chlorine dioxide gas fumigation on the storage quality of astringent persimmon (Diospyros kaki T.) Cheongdobansi

Because of their short harvest season, large quantities of persimmons must often be processed within a limited time. Therefore, new methods to extend their storage life are required. This study examined the effects of chlorine dioxide (ClO2) gas fumigation for various treatment periods on the storage quality of astringent persimmons Cheongdobansi under low-temperature conditions. The conditions consisted of continuous treatment with ClO2, treatment for 2 weeks with ClO2, and no treatment, all of which are stored at low temperatures. Control samples (storage 0 days) without any treatment were prepared and all experiments were conducted for 10 weeks at two-week intervals. The ClO2 gas treatment maintained the moisture content, color value, hardness, soluble tannin content, and sensory characteristics. However, ClO2 gas treatment did not affect the soluble solids, pH, and total sugar content. In particular, continuous treatment with ClO2 maintained the storage quality after 6-8 weeks of storage, particularly the hardness and weakness (sensory evaluation). The results suggest the potential of continuous treatment with ClO2 as a highly effective method for maintaining the freshness of Cheongdobansi.

Impacts of ozone stress on stem lodging characteristics of different indica and japonica rice cultivars

AbstractOzone (O3) stress inhibits rice growth and development, resulting in yield loss and poor quality. However, the effect of ozone stress on the lodging resistance of rice stems has scarcely been reported. In this study, three indica rice cultivars and three modern japonica rice cultivars were treated with high O3 concentration (100 ppb) while a gas fumigation platform was used in the indoor control (about 10 ppb). The influence of O3 stress on lodging resistance was investigated in 2016 and 2017. Ozone stress reduced the in situ pushing resistance of intact plants by 40% and single stems by 32.0%. The breaking resistance of the third, fourth, and fifth internodes from the top of the rice stem was, respectively, reduced by 24.0%, 25.1%, and 33.6%, on average. The O3‐induced reduction in the basal internode morphological characteristics was associated with the reduced cross‐sectional area, maximum and minimum stem diameter, dry weight per unit length, length, dry weight, and culm wall thickness. Among these characteristics, the largest reduction was exhibited by internode dry weight (−43.1%), while the lowest reduction was observed for culm wall thickness (−9.7%). The O3 induced a significantly higher reduction in basal internode characteristics of indica compared with the japonica rice, with a larger effect in the lower internode than the upper internode, indicating a significant interaction between O3 and rice cultivar and internode position. Statistical analysis revealed a significant positive linear correlation between the response of in situ pushing resistance of rice under O3 stress and the response of basal internode breaking resistance, cross‐sectional area, and dry weight per unit length. Ozone stress significantly reduced the lodging resistance in the rice stem, which is primarily associated with the thinning and poor filling of the basal internodes, and the O3 impacts varied with cultivars and internode positions, but were similar between the two years. These results provide a scientific reference for the study of lodging resistance regulation of rice under high O3 concentrations.

Fumigation Monitoring and Modeling of Hopper-Bottom Railcars Loaded with Corn Grits

IntroductionBulk railcars are a common method of moving commodities in the USA. Allowances are given for the practice of treating railcars with fumigates during transit because the routes are limited access and not on public roads. Recent technology has become available for monitoring phosphine gas (PH3) fumigation on railcars which logs the phosphine concentration and temperature of the test point in the railcars.Materials and MethodsTwo hopper bottom railcar shipments of corn grit were monitored for phosphine during 8-day transit from mill to processor. Several phosphine-sensing units were used in each railcar and spaced across the top layer. Mathematical modeling of the railcar fumigation was carried out using computational fluid dynamic software. Because access to lower depths in the railcar was not available, supplement experiments were performed with small columns of corn grits (2.5 m height x 0.55 m diameter) to test for phosphine at greater depths. Also, in the grain columns, bioassays of both phosphine susceptible and resistant, adult Rhyzopertha dominica (F.), lesser grain borer, and Tribolium castaneum (Herbst), red flour beetle, were included at the 0 cm, 25 cm, and 60 cm below the surface.ResultsThe phosphine concentrations in the railcar headspace varied with time with phosphine spiking over 1600 ppm and gradually settling to over 300 ppm at the end of the 8 days. Total gas dosage was estimated as concentration*time (CT) over the 8 days as 115,000 and 125,000 ppm*h at the top of each railcar. The supplement grain column fumigation tests found significant phosphine penetration into the column at 2 m depth with ~380 ppm after 2 days which reduced to ~260 ppm after 8 days, and all insects, at all locations, were dead after 8 days. The CFD simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well with the observed data, validating the CFD approach as a useful tool.DiscussionThe simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well the observed data, validating the CFD approach as an efficient tool for future planning and analysis of similar fumigations.

Effects of small-scale storage on the cooking property and fatty acid profile of sea rice paddy

This research investigated the storability of sea rice paddy in an experimental silo for 11.5 months. Water was circulated in the silo walls from June 30 to maintain a grain bulk temperature of 23°C. The dry-bulb temperatures in three layers (top, middle, and bottom) of paddy bulk showed very small differences, but the intergranular air parameters such as relative humidity (RH), wet-bulb temperature and humidity ratio in middle and bottom bulk layers were significantly higher than those of top bulk layer, and storage insects occurred in these two bulk layers from August to September as a result that sulfuryl fluoride gas fumigation was done on September 30. During storage, the rice's water absorption rate and gruel solids loss decreased with storage time, while the peak temperature of gelatinization (Tp) increased, and water uptake ratio and taste panel score remained unchanged. Fatty acid profile analysis shows that the total, saturated, and unsaturated fatty acid concentrations decreased with storage time, while the unsaturated-to-saturated fatty acid ratio increased. Compared to top bulk layer, the bottom layer had lower water absorption rate and fatty acid concentration, and a similar Tp and better cooking property. Further compared with a short-grain Japonica paddy (cv. Yanfeng) stored in a large cooled warehouse before and after oversummering, sea rice paddy stored in the experimental silo had lower protein content, but had a higher Tp, poly-unsaturated fatty acid content and unsaturated-to-saturated fatty acid ratio, and similar amylose content and taste panel score. These results suggest that sea rice has good storability, and quasi-low-temperature storage (23°C) requires autumn chemical fumigation to control the storage insects.

A critical Review of Dhoopan Karma in Ayurveda and Dhoopana of an Ayurvedic Herbomineral formulation Yavasarshapadi churna in context of Sterilization.

Dhoopana Karma is classical remedy mentioned in various Ayurvedic scriptures to maintain disease free and hygienic environment in the world. As per Ayurvedic scriptures Dhoopana is indicated for Rakshoghna Karma which means killing of disease producing microorganisms. Hence, it plays key role in prevention and cure of various infectious diseases.A similar process called fumigation is one of best and fastest method to maintain asepsis, antisepsis in wards and operation theatres of hospitals.Additionally, this study comprises critical literary review of herbomineral formulation named Yavasarshapadi Choorna which is indicated in form of incense for Dhoopana karma. It is indicated in Ayurvedic scripture Charaka Samhita in chapter Jatisutriya Sharir Adhyaya of Sharir Sthana. It was reviewed in context of sterilization activity to maintain asepsis and antisepsis. Specifically, it is indicated for fumigation of cloths and belongings of post-natal period of Women and that of the New born, Drug preparation room, New born care room, Surgical Procedure room modern surgery, traditional operation theatre sterilization was done by formalin gas fumigation over many decades which is found to have carcinogenic effect over human lives. Ayurvedic modality named Dhoopana was undertaken in current study as it is a safe and healthy alternative for sterilization.It overcomes harmful effects caused by modern sterilization method i.e. Formalin gas fumigation which is need of an hour. The Analytical study of antimicrobial and antifungal effect of various Ayurvedic Dhoopana Dravyas is the need of the hour along with preclinical and clinical study to verify Sterilization activity of various Ayurvedic Dhoopana Dravyas.

Performance, Emission, and Economic Perspectives of a Diesel Engine Fueled with a Mixture of Hydroxy Gas and Biodiesel from Waste Palm Cooking Oil

This investigation experimentally examines the influence of hydroxy gas fumigation in a diesel engine fueled with a biodiesel blend derived from waste palm cooking oil (B10). For the experimental tests, a fixed rotation speed of 2000 rpm and a load condition of 50%, 75%, and 100% have been established. Hydroxy gas (HHO) has been added through the engine's air intake system at a flow of 0.5 lpm, 0.75 lpm, and 1 lpm. Results have demonstrated the positive effect of HHO fumigation on the combustion performance of the B10 blend. Moreover, a reduction of 4.3% in the BSFC and a 2.64% increase in peak pressure in B10 due to the presence of HHO have been observed. On the other hand, a decrease of 8.7%, 9.9%, and 22.8% in CO2, HC, and smoke opacity emissions has been evidenced with the addition of HHO in B10. B10 implementation has promoted NOx emission escalation. However, this increase has been only 1.23% compared to pure diesel. In conclusion, HHO enrichment favors combustion performance and emissions minimization, which represents a significant opportunity to mitigate the negative effect of the lower calorific power of these types of fuels.

Risk Assessment of Ozone Fumigation Under Vacuum to Control Potential Infestation of Coffee Berry Borer and Coffee Leaf Rust in Green Coffee Beans Imported Into Hawaii.

Studies were conducted with ozone gas fumigation under vacuum as a methyl bromide alternative against life stages of coffee berry borer (CBB) Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), and the urediniospores of coffee leaf rust (CLR), Hemileia vastatrix Berkeley & Broome (Basidiomycota: Pucciniales) in green coffee, Coffea spp. L. Fumigation with 10,000 ppm O3 gas under -25.4 mm Hg vacuum1 at 13.0 ± 3.0°C for 6.0 h killed all CBB larvae, pupae, and adults, but did not kill all CBB eggs (~15% survival). Mortality of CLR urediniospores was 100% within the first hour of the 6-h fumigation. Ozone fumigation had no adverse effects on coffee quality. Results indicated that CBB adult hitchhikers may be the only target life stage of quarantine concern, and additional studies focused on this stage. CBB adult survival and reproduction decreased significantly at moisture contents ≤20%, and F1 generation survival did not occur in green coffee at moisture contents ≤15%. As the international standard for green coffee moisture content is 9-12%, adult CBB should not survive or reproduce in exported dry green coffee. Standard industry processing of harvested coffee cherries to the green coffee stage using either mechanical- or sun-drying eliminated CBB infestations from the field. A systems approach is recommended for exporting green coffee to control CBB and CLR that includes eliminating CBB life stages with standard processing methods, reducing moisture content to 9-12% to prevent egg deposition, survival or reproduction, and O3 fumigation to ensure quarantine security against potential CBB adult hitchhikers.

Effects of High Concentration Ozone Gas Fumigation on the Quality and Shelf-life of Longan Fruit

ABSTRACT The objective of this research was to study the effects of high concentration ozone (HCO) fumigation on the shelf-life of fresh longan. Longan was exposed to ozone gas at varying inlet concentrations of 4,000, 8,500, and 13,000 ppm with holding times of 5 and 15 min. Results showed that the longan exposed to ozone gas at 8,500 ppm for 5 min was considered a suitable treatment to extend shelf-life up to 35 days, which is 57% longer than the shelf-life of non-ozonated longan. The SEM revealed that the ozonated longan had less surface epidermal hairs than the non-ozonated longan.

Field Evaluations of Sulfuryl Fluoride Fumigation for Control of the Common Bed Bug (Hemiptera: Cimicidae), Using a 1.9× Dosage Factor in Motor Vehicles and Filled Cargo Trailers.

This study investigated the efficacy of using Vikane gas fumigant (sulfuryl fluoride) at the 1.9× dosage rate for eliminating bed bugs (Cimex lectularius L.) in two challenging infestation situations: personal vehicles, and confined spaces densely packed with personal belongings. The vehicles used in this study were large minivans with seating that folded into the floor. The confined spaces were cargo trailers filled to 85% capacity with books, furniture, and other household items. Each van and trailer was equipped with ~90 sentinel bed bugs consisting of three groups of 9-11 bed bug eggs, 10 nymphs, and 10 adults. The Vikane Fumiguide calculator was used to determine the target dosage (g-h/m3) to apply in each replicate (e.g., one van or trailer). Sulfuryl fluoride concentrations were measured throughout the fumigation process using a Spectros SF-ReportIR. Concentration readings were input into the Fumiguide to determine when the accumulated dosage (g-h/m3) was achieved, and when aeration should be initiated. After aeration was complete, the sentinel bed bugs were removed from the replicates and bed bug nymph and adult mortality was recorded. Bed bug eggs were monitored for 23 d to determine latent mortality. Fumigated bed bug mortality for each replication was 100% regardless of life stage. Latent mortality was observed in a single bed bug egg, but the first instar never fully eclosed. This study determined that fumigation with sulfuryl fluoride at the 1.9× dosage factor is an effective method for eliminating resistant bed bugs from vehicles and personal belongings in densely packed situations.

Effects of hexanal fumigation on fungal spoilage and grain quality of stored wheat

The prevention of fungal spoilage is an essential consideration in wheat storage. Recent studies have revealed that volatile organic compounds (VOCs), possibly with natural fungicidal properties, could be produced from stored wheat grains. In this study, the antifungal effect of hexanal, a main component of VOCs from stored wheat, against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method. And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content, fatty acid values, germination percentages and vigor of 16% and 18% moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor. The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal (fatal) concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid, respectively. The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor. During 5-week storage of high-moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor, the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples, and fatty acid values were slightly higher in 18% moisture wheat than in 16% moisture wheat. The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content. These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Transcriptome profiling of postharvest kiwifruit in response to exogenous nitric oxide

Nitric oxide (NO) is a signal molecule that can regulate fruit physiology. Several studies have indicated that NO can inhibit the ripening of kiwifruit, but the mechanism underlying this process is unresolved. This study used transcriptome analysis to identify the essential genes related to NO regulation during kiwifruit softening. NO gas fumigation (15 μl L-1) significantly delayed kiwifruit softening. There were 736 differentially expressed genes (DEGs) between the NO treatment and the control. The expression levels of polygalacturonase (PG), pectate lyase (PL), β-galactosidase (β-GAL), pectinesterase (PE), and the beta-amylases-related genes decreased in response to the NO treatment, while those of four genes encoding cellulose synthase increased. The expression of genes related to ethylene biosynthesis and signal transduction also differed; the expression levels of 1-aminocyclopropane carboxylic acid oxidase (ACO), the ethylene receptors (ERS1, ETR2), and the ethylene-responsive transcription factors (ERF016, ERF7, ERF010, ERF062, ERF110, ERF037, ERF008, ERF113, ERF12, ERF095) were lower in the NO-treated kiwifruit. Expression of the calcium ion (Ca2+) signal-related genes (CNGC1, CPK1, CIPK2, CML31, CML48, ZIFL1) significantly differed and may be involved in the regulation of the NO softening response. These findings add to our understanding of the molecular mechanisms of the NO-delayed softening response in kiwifruit.

Effects of ozone stress on amylose content and starch RVA profile in grains located at diffe-rent positions on a panicle

The increase of ground-level ozone concentration significantly reduces rice yield, but its effect on grain quality in association with the positions on a panicle was largely unknown. The effects of ozone stress on amylose content and RVA profile of rice grains located at different positions of panicles were studied by using a sunlit gas fumigation platform. Eight varieties representing different types of rice were fumigated under ambient (9 nL·L-1) or elevated ozone (100 nL·L-1) concentrations from transplanting until maturity. The results showed that elevated ozone treatment significantly reduced amylose content, maximum viscosity, hot viscosity, breakdown and cold viscosity by 5.9%, 7.6%, 5.9%, 11.6%, 2.9%, respectively, but increased the setback and gelatinization temperature by 24.9% and 1.0%. There were significant differences among varieties for amylose content and all parameters in RVA profile. The grains located at different positions on a panicle differed in amylose content, maximum viscosity, hot viscosity, breakdown and cold viscosity. The superior grains located at the upper part of a panicle had the highest value and the inferior grains located at the lower part of a panicle had the lowest value. However, the setback in RVA profile showed a different trend, with the superior grains having the lowest setback but inferior grains having the highest setback. In most cases, there were significant interactive effects of ozone by year or ozone by variety on amylose content and RVA profile. No significant ozone by grain position interaction on RVA profile was found, although the responses of superior grains to ozone stress was slightly smaller than those of inferior grains or grains located at the middle part of a panicle. The results demonstrated that ozone fumigation of 100 nL·L-1 during rice growing season deteriorated rice quality, with the magnitude of deterioration varying with growth seasons and varieties and little impacts of grain positions on a panicle.

APLIKASI FUMIGAN GAS FOSFIN (HIDROGEN FOSFIDA (PH3)) UNTUK PENGENDALIAN TIKUS (RODENT)

Rats are widely distributed disease spreaders and settlement pests. Species of rats often found include Rattus norvegicus, R. tanezumi and Mus musculus. Phosphine as a fumigant is commonly used to control pests with no residue, especially related where there are placed the commercial products . The research objective was to determine effect of phosphine gas fumigant (hydrogen phosphide (PH3)) on rat death. The study sample was species of rats, i.e. M.musculus, R.tanezumi, and R.norvegicus. This study was used 4 dose variations (0, 4, 6 and 8 tablets) with 6 replications per unit treatment. Each treatment (dosis) needed 1 rat . The results of different test analyzed that significance value was 0.0001 (p=0.0001), indicating that there were differences in average time span of M. musculus, R. tanezumi and R. norvegicus death to treat of phosphine dose variations. Based on Probit analysis, the data showed that The fastest LT50 and LT99 were at a dose of 8 tablets for 90.5 and 114.9 minutes, and LT50 and LT99 were at the lowest dose of 4 tablets in 148.1 and 188.1 minutes, respectively. The higher dosage of phosphine was treated, the higher gas concentration was produced, so that it could kill M. musculus, R. tanezumi dan R. norvegicus quickly. The mortality might be generated by cell damages that occurred inside the body of rats.
 
 
 

Web-based monitoring system using Wireless Sensor Networks for traditional vineyards and grape drying buildings

The quality of grapes and the drying process has a momentous impact on the quality of the final products (raisins). South Azerbaijan is the most important region for grape growing and raisin producing. However, the majority of the vineyards in the region are traditional, and the drying process is carried out in conventional structures that are not convenient. To increase the quality and productivity, it is necessary to modernize agricultural practices with reasonable cost suitable and affordable to traditional farming and farmers. To do this, the harsh environments and severe climate conditions of the vineyards and the drying buildings should be observed periodically to collect data. Wireless Sensor Networks are a key technology that can provide precise information, can update information, and can be a valuable resource to farmers to determine appropriate management practices. Using this technology, farmers can make real-time decisions such as scheduling irrigation periods, preventing diseases, choosing the right time for harvesting and so on. In this project, a Wireless Sensor Network system was designed and developed for remote real-time monitoring and collection of micrometeorological parameter data in three distant vineyards. The system was also used for monitoring the SO2 gas fumigation process and atmospheric parameters inside the drying structure. The system consists of a gateway and a series of peripheral wireless motes placed in the vineyards and inside the drying structure, which are equipped with agrometeorological sensors for environmental monitoring and for storing and transmitting data to the gateway. The gateway collects agrometeorological data and utilizes a wireless technology for data transmission and for communication between the motes and the central server (webpage). In addition, an on-line (real-time) warning system was embedded in the gateway to send alarm signals via SMS (Short Message Service). The devices were tested for software configuration functionality, hardware operation and data acquisition, energy consumption, and connectivity. Field experiment results demonstrated that the system represents a complete monitoring system, which provides efficient performance for developing information systems in precision viticulture.

이산화염소 가스 훈증 처리에 따른 곶감의 미생물학적 변화 및 품질특성

This study was conducted to investigate the effect of chlorine dioxide fumigation as a substitute for sulfur fumigation which has been used as a method to prevent the quality change of persimmon during storage and distribution process. Dried persimmons were treated with chlorine dioxide gas concentration (0, 15 30, and 45 ppm) and time (0, 15, 30, and 45 min) and microbiological changes, texture properties and color of the treated samples were investigated during storage at room temperature. Total aerobic bacteria, yeast and mold numbers after chlorine dioxide gas fumigation were decreased when compared with the control group. The inhibitory effects of total aerobic bacteria, yeast, and mold were observed during storage. The texture properties and color value of dried persimmons were not affected by chlorine dioxide gas fumigation concentration and time. There was no difference in quality between chlorine dioxide gas fumigation treatment group and control group. These results suggested that chlorine dioxide gas fumigation treatment can be utilized as a processing technique to secure microbiological storage stability of dried persimmons.

Suppression of Fusarium wilt of cucumber by ammonia gas fumigation via reduction of Fusarium population in the field

Cucumber plants subjected to consecutive monoculture for 9 years were found to suffer from severe Fusarium wilt disease, caused by the soil-borne fungus Fusarium oxysporum f. sp. Cucumerinum J. H. Owen. In the present study, greenhouse experiments were performed to evaluate the influence of ammonia gas fumigation on Fusarium wilt suppression, fungal abundance and fungal community composition. Results showed that ammonia gas fumigation remarkably reduced disease incidence from 80% to 27%, resulting in a four-fold increase in yield, compared to the control. Total fungal abundance declined dramatically after fumigation and reached the lowest level at day 32, at 243 times lower than the control. Moreover, fumigation significantly increased soil fungal diversity, though it also decreased considerably coinciding with cucumber growth. Fumigation also significantly altered soil fungal community composition, relative to the control. Fusarium was strongly inhibited by fumigation in both relative abundance (3.8 times lower) and targeted quantification (a decrease of 167 fold). Collectively, the application of ammonia gas fumigation to control Fusarium wilt of cucumber resulted in a re-assembly of the fungal community to resemble that of a non-disease conducive consortium. Additional strategies, such as bioorganic fertilizer application, may still be required to develop sustainable disease suppression following fumigation.

Flow field and traverse times for fan forced injection of fumigant via circular or annular inlet into stored grain

Fan forced injection of phosphine gas fumigant into stored grain is a common method to treat infestation by insects. For low injection velocities the transport of fumigant can be modelled as Darcy flow in a porous medium where the gas pressure satisfies Laplace’s equation. Using this approach, a closed form series solution is derived for the pressure, velocity and streamlines in a cylindrically stored grain bed with either a circular or annular inlet, from which traverse times are numerically computed. A leading order closed form expression for the traverse time is also obtained and found to be reasonable for inlet configurations close to the central axis of the grain storage. Results are interpreted for the case of a representative 6 m high farm wheat store, where the time to advect the phosphine to almost the entire grain bed is found to be approximately one hour.

The impact of elevated CO2 and temperature on grain quality of rice grown under open-air field conditions.

Rising atmospheric CO2 is accompanied by global warming. However, interactive effects of elevated CO2 and temperature have not been well studied on grain quality of rice. A japonica cultivar was grown in the field using a free-air CO2 enrichment facility in combination with a canopy air temperature increase system in 2014. The gas fumigation (200 µmol mol(-1) above ambient CO2 ) and temperature increase (1 °C above ambient air temperature) were performed from tillering until maturity. Compared with the control (ambient CO2 and air temperature), elevated CO2 increased grain length and width as well as grain chalkiness but decreased protein concentrations. In contrast, the increase in canopy air temperature had less effect on these parameters except for grain chalkiness. The starch pasting properties of rice flour and taste analysis of cooked rice indicated that the palatability of rice was improved by CO2 and/or temperature elevation, with the combination of the two treatments showing the most significant changes compared with ambient rice. It is concluded that projected CO2 in 2050 may have larger effects on rice grain quality than the projected temperature increase. Although deterioration in milling suitability, grain appearance and nutritional quality can be expected, the taste of cooked rice might be better in the future environment. © 2015 Society of Chemical Industry.