Glasshouse Vegetables Research Articles

The Automation of the Mathematical Model of Heated Glasshouses

The analysis of technical operations associated with growing vegetables in glasshouses shows that it is possible to reduce labor inputs and improve the efficiency of indoor growing structures through a specific set of technical solutions. The facilitation of the fundamental improvement of the glasshouse vegetable production technology requires stationary transportation systems and robot hardware. The glasshouses can be classified according to their functional and structural properties: intent, seasonality, growing practices, the type of transparent cover, the type of frame, and heating method. In this case, detailed thermophysical models should not be used. The lack of properly rationalized mathematical models for heated glasshouses holds back their development and improvement. When creating such models, it is necessary to consider heat and mass transfer processes taking place in the glasshouse, the distribution of their parameters, and the accidentality of external impacts. Additional problems arise because the requirements set for models rarely comply with the research goals set or do not reflect the conditions, under which it is used. The suggested balanced dynamic models allow for the extensive use of computers to research heat consumption patterns in glasshouses and synthesize temperature regulators. The mathematic methods for such calculations comprise vector-matrix algebra, for the respective software is widely available on various computers. Growing plants indoors during winters and springs requires the maintenance of climatic factors influencing the growth and development of plants. Due to this, automated control of such factors in compliance with agricultural practices receives great importance. To maintain temperatures automatically in hotbeds, two-position control systems are used. Large glasshouse businesses are currently introducing intensive vegetable growing technologies, and automated workflow control systems based on micro- and minicomputers. Key production activities include the watering and mineral fertilizer dressing of plants. These processes must be automated because they require large labor inputs during the preparation of the solution, the maintenance of the required content proportions, timely feed, and even distribution across all of the glasshouse under various external impacts.

Effect of the extract and compound from Solanum nigrum Linn on Tetranychus cinnabarinus

AbstractThe carmine spider mite Tetranychus cinnabarinus (Boisduval) is a serious pest affecting various glasshouse vegetables, fruits and crops and causes significant damage to crop yields and quality by piercing and sucking foliar tissues. The control of this mite primarily involves the application of synthetic chemical pesticides. In this study, a Solanum nigrum L. extract was evaluated for its potential acaricidal activity against adult female T. cinnabarinus in laboratory conditions, and the S. nigrum extract showed marked efficacy in controlling the carmine spider mite both in vitro and in potted seedlings. Furthermore, the active compound, a phytostanol ester (β‐sitosterol‐3‐O‐heptadeca‐8Z, 11Z‐dienoate), was isolated from the petroleum ether‐soluble fraction of S. nigrum extract via repeated column chromatography and identified based on its physiochemical properties and spectral data. At 7 days after treatment in a potted seedling experiment, the LC50 values of the S. nigrum extract and active compound were found to be 4.70 and 1.85 g/l, respectively. All of these results demonstrated that the S. nigrum extract and its active component exhibit the potential for use as new natural acaricides for controlling carmine spider mites.

Economic Effects of Using Geothermal Waters in the Production of Flowers and Vegetables in Glasshouses

Using geothermal waters in growing flowers and vegetables in the glasshouses represents the most modern form of production in sheltered areas, which enables the realization of a production cycle during the whole year, along with decreased energy costs. According to a study research, which was done in the area of South and East Serbia (first of all in the municipality of Vranje), in the paper were shown the economic effects of flowers and vegetables production, which can be expected by starting the production in modern glasshouses, along with the geothermal waters use. A basic goals of the research is to point out to peculiarities of flowers and vegetables production in the modern glasshouses, as well as to determine, based on the analysis of the gross reimbursement margin (gross financial result) in production of cut flowers (i.e. roses, gerbera and calla) and vegetables (i.e. tomato, cucumber and pepper), in which production line can be realized the best results. Accordingly, by making the analytical calculations based on the variable costs, was determined that the best results can be expected for roses (cut flowers production line) and tomato (vegetable production line).

Biocontrol of Pests on Plant Crops in Denmark: Present Status and Future Potential

In this review, the status of biocontrol in plant crops in Denmark is analysed and factors governing the present use and future potential are described. In glasshouse vegetables, biocontrol is the dominant method to control pests while it is much less used in glasshouse ornamentals. On outdoor crops, the use of biocontrol is negligible. The main factors determining future prospects include: research, political initiatives, the scale of organic farming, the interest of companies marketing and advising on biocontrol, and public opinion. Good communication between scientists, advisers, growers, government authorities and the public has occurred for many years in Denmark, and has been essential for the successful implementation of biocontrol in glasshouses. Future development of microbial control (to which some organic growers and some members of the public show concerns) will require both research and a debate among the partners, particularly about environmental safety.

Detection of soil‐borne pathogens in glasshouse‐grown ornamentals*

The Research Station for Floriculture and Glasshouse Vegetables focuses its activities on the entire glasshouse horticulture chain. Research involves many different ornamental crops, each with its own specific problems with respect to pest control. Correct diagnosis of diseases is very important in order to give good advice for control strategies. With the introduction of integrated and supervised control strategies, pathogen monitoring has become even more important. In general, diagnosis is carried out by conventional methods using selective media to isolate and identify the pathogen. These methods can be time‐consuming and result in the identification of a single pathogen at a time. Diagnostic methods based on isozyme patterns have also been used for the detection of fungal pathogens in infected plant material. Specific isozyme methods have been developed for the diagnosis of Fusarium oxysporum f. sp. cyclaminis in cyclamen, F. oxysporum f. sp. gladioli in gladiolus, Gnomonia radicicola in rose, and Phytophthora nicotianae, Phytophthora sp. and Cylindrocladium spathiphylli in spathiphyllum. Current and future work is focussing on identification of plant pathogens in contained environment‐culturing systems using molecular techniques.

Novel approaches to integrated pest and disease control in glasshouse vegetables in the Netherlands

AbstractAs a result of government policy and consumers' attitudes to environmentally compatible growing systems, research is focused on reduction of pesticide input into the environment. This aim is approached in different ways.With so‐called “closed growing systems”, soil fumigants are no longer needed, resulting in an estimated 60% reduction in the total use of pesticides. Further, far smaller quantities of (systemic) pesticides need to be added to plants, via the nutrient solution, than with soil‐grown crops. Water disinfestation is essential to minimize the spread of diseases and heat treatment and ozonization are already used under commercial conditions. Filtration appears to be neither reliable nor practical. Other disinfestation methods are under investigation.Ventilators may be provided with insect‐proof screens to minimize infection pressure, especially on young plant material. Air filters in combination with mechanical ventilation may be an option for the future to raise healthy plants.A further reduction in the use of pesticides can be achieved by developing biological and integrated control of insects and fungi. Simultaneous application of several biocontrol methods in the fruit vegetable area has increased the complexity of IPM. Open rearing systems of parasitoids on alternative hosts to control cotton aphids and leaf miners are promising. IPM is highly dependent on the availability of selective chemicals.Biological control of root‐infecting fungi in substrate crops shows promise. Integrated control of powdery mildew in cucumbers using a combination of nutritional and climatic management and varieties showing partial resistance will be studied.Improvement of application techniques for pesticides is being studied by plant pathologists in cooperation with technical experts. The aim is to reduce pesticide application rates, to minimize losses to the environment and to avoid health risks for the worker.By developing decision‐support systems for crop protection, optimal use of beneficial insects is achieved and unnecessary applications of chemicals are avoided. A programme to develop such a system for the sweet pepper crop is under way.

Reproduction of Dacnusa sibirica (Hymenoptera: Braconidae), an Endoparasitoid of Leafminer Liriomyza bryoniae (Diptera: Agromyzidae) on Tomatoes, at Constant Temperatures

The parasitoid Dacnusa sibirica Telenga is currently used for seasonal inoculative biological control of the leafminers Liriomyza bryoniae (Kaltenbach) and Liriomyza trifolii (Burgess) on glasshouse vegetables in northwest Europe. The braconid is effective from the beginning of the season until July, when average temperatures vary between 15 and 20°C. To estimate the potential reproduction (R) of the parasitoid, the effect of temperature (15, 20, and 25°C) on its fecundity, longevity, and oviposition rate was examined in the laboratory. Fecundity and longevity decreased with increasing temperatures, but did not differ significantly between 20 and 25°C. Oviposition rate was highest at 20°C, apparently the optimum temperature for oviposition. The R of D. sibirica decreased with increasing temperatures. Therefore, D. sibirica is expected to be less effective for the biological control of leafminers on tomato at high temperatures. The use of potential population growth, R or rm, to evaluate parasitoids' effectiveness is discussed.

Studies on the application of iron to some glasshouse vegetables grown in soilless culture

The application of iron to some glasshouse crops in soilless culture was studied in the course of an investigation. The growing systems consisted of nutrient film technique and rockwool. The test crops were tomatoes, cucumbers and sweet peppers.

Nitrate and glasshouse vegetables

Leafy vegetables grown under glass in winter have a rather high nitrate content. Three possibilities of reducing this content are discussed: the use of nitrification inhibitors, growing on NFT and omission of nitrogen during a certain period before harvest, and the breeding of varieties with a low nitrate content. In the last chapter the question whether high nitrate levels in vegetables are dangerous to human health is briefly discussed.

A whitefly-transmitted disease of glasshouse vegetables, a novelty for Europe

Sinds eind 1978 wordt in toenemende mate onze aandacht gevraagd voor een vergelingsziekte bij sla, andijvie en komkommer, die in kassen worden geteeld. De ziekte komt soms reeds in schadelijke mate voor. De symptomen gelijken geheel op die van het door bladluizen verspreide slavergelingsvirus. De ziekte kon bij de genoemde gewassen worden overgebracht door de kaswittevlieg (Trialeurodes vaporariorum) maar o.a. ook op enkele tabakssoorten. Het gaat hier waarschijnlijk om een virusziekte en de verantwoordelijke verwekker is waarschijnlijk identiek aan het in 1965 in Californie beschreven en tot dusver nog maar eemaal gerapporteerde ‘beet pseudo-yellows virus’ dat daar bij onderzoek als verontreinigere optrad, maar in staat was om vele plantesoorten te infecteren. Voor het virus werd de Nederlandse naam pseudoslavergelingsvirus ingevoerd. Over de verwantschap met een onlangs in Japan beschreven verwekker van een door dezelfde wittevlieg overgebrachte kasvergelingsziekte van komkommer en meloen bestaat nog onzekerheid. Door wittevliegen overgebrachte virussen komen veelvuldig en in een schadelijke mate voor in de tropen.

BRITISH HORTICULTURE AND THE COMMON MARKET

Tariffs and quotas against the Six are not consistent with Britain as a part of the Common Market. Such restrictions have produced the traditional policy for horticulture in Britain. Now their removal is threatened and with it the incomes of our producers.This paper attempts to measure the seriousness of the threat to British growers. Three features are most relevant to this question. Firstly, somewhat less than two‐thirds of the producers depend wholly on income from horticultural produce. Secondly, only one‐tenth of the producers account for two‐thirds of the output. Thirdly, horticultural produce is of distinct types, decorative, dessert, salad, or staple, and the future demand and supply prospects vary accordingly.The E.E.C. is poised to send us more glasshouse vegetables and more apples and pears. Thus the most highly capitalised sectors of horticulture are most vulnerable and those growers with modernised investment will best meet the increased competition. The future will see further adjustment within the industry, but the outcome will mainly depend on the general level of prosperity in Britain.

Vegetables Under GlassThe Forcing Book; A Manual of the Cultivation of Vegetables in Glass Houses. L. H. Bailey

Vegetables Under Glass<i>The Forcing Book; A Manual of the Cultivation of Vegetables in Glass Houses</i>. L. H. Bailey

The Forcing-Book: a Manual of the Cultivation of Vegetables in Glass-houses

THIS is a small manual devoted to an explanation of the principles, and to a statement of the practices involved, in “forcing for market.” In no department of horticulture do experience and judgment tell more than in forcing operations; but if “practice” be essential, it is certain that to get the best results, it must be directed by trained intelligence. In this country market-gardening under glass has greatly extended of late years, and many agriculturists, rinding it no longer remunerative to grow wheat, have turned their attention to the growth of flowers or to market-gardening generally. As a rule these men have been successful because they have known how to adapt themselves to new conditions, and have not been mere slaves to routine. As competition increases it may be expected that market-gardening will become less remunerative, and hence the necessity for increased knowledge and quickened intelligence in order to meet the new circumstances. In the United States, in Germany, in France, in Belgium, in Denmark, this truth has been recognised, and horticultural schools and experiment stations have been established for years. In this country, as is usually the case in such matters, we have lagged behind, and have many arrears to clear off before we can deem ourselves on a level with the countries we have mentioned. And all this time we are importing, to an enormous amount, commodities a large proportion of which might be grown at home.