Greenhouse Tomato Crops Research Articles

Evaluation of event-based irrigation system control scheme for tomato crops in greenhouses

This work presents a study and evaluation of an event-based predictive control system for a greenhouse irrigation process. The control system objective is to maintain the desired substrate humidity level, keeping the water usage as low as possible. The event-based control scheme uses a crop transpiration model to determine the volume of water required to compensate for the irrigation system and a water content model to trigger the irrigation system events. First, simulation experiments were performed to analyze the behavior of the designed system and to study the water supply dynamics to the substrate and subsequent drainage and evaporation. Secondly, the proposed event-based controller was evaluated in an experimental greenhouse, located in southeast of Spain, in real operation conditions. The resulting control system is able to adapt the actuation rate to the state of the plant providing the efficient way of water consumption. The obtained results show that the application of proposed event-based approach for the greenhouse irrigation system allows to improve the control performance and to reduce the water usage (about 20% of required water for the same performance obtained for commonly used on/off) being an important issue in intensive agriculture. The improved control performance is obtained due to event-based approach and the inclusion of information about the plant dynamic response for water supply and transpiration effect.

Canary Greenhouse CFD Nocturnal Climate Simulation

The aim of this paper is to predict in details the distributed nocturnal climate inside a one hectare Moroccan canary type tomato-greenhouse equipped with continuous roof and sidewalls ventilation openings with fine insect screens, by means of 3D CFD (Computational Fluid Dynamics) simulations by using a commercial Software package CFD2000 based on the finite volumes method to solve the mass, momentum and energy conservation equations. The turbulent transfers were described by a k-e model. Likewise, the dynamic influences of insect screens and tomato crop on airflow movement were modeled by means of the concept of porous medium with the Boussinesq assumption. Atmospheric radiations contribution was included in the model by customising the plastic roof cover temperature deducted from its energy balance. Also, the CFD code was customized in order to simulate in each element of the crop cover the sensible and latent heat exchanges between the greenhouse air and tomato crop. Simulations were carried out with a wind prevailing direction perpendicular to the roof openings (west-east direction). Simulations were later validated with respect to temperature and specific humidity field measurements inside the experimental greenhouse. Also, the model was verified respect to global sensible and latent heat transfers. Results show that, generally, greenhouse nocturnal climate distribution is homogeneous along the studies greenhouse area. The insect proof significantly reduced inside airflow wind speed. But there is no significant effect on the inside air temperature and specific humidity respect to outside.

土壤水分胁迫对设施番茄根系及地上部生长的影响

土壤水分胁迫对设施番茄根系及地上部生长的影响

Seasonal phenology of Tuta absoluta (Lepidoptera: Gelechiidae) in protected and open-field crops under Mediterranean climatic conditions

The population structure and dynamics of the tomato leafminer Tuta absoluta were investigated in a protected tomato crop and on potato and tomato crops and Solanum nigrum plants under open-field Mediterranean climatic conditions (Sardinia) by captures in pheromone-baited traps and visual inspection of host plants. In the greenhouse crop, male captures and leaf infestation were low in winter and increased steadily in spring up to 797.3 males/trap/week and 6.4 mines/leaf, respectively. Under open-field conditions, males were captured all year round with a peak in early September, concurrently with highest mean daily temperatures. Pest density in potato crops was very low (<0.3 mines/leaf), as well as on S. nigrum (0.16 mines/leaf). Conversely, high pest infestation was observed in tomato leaves (3.8 mines/leaf) and fruits (27% damaged fruits). Eggs, larvae and adults were detected over two consecutive winters, indicating that T. absoluta can develop continuously over the year under natural conditions. Parasitoids were recorded throughout the survey at low rates (≤16.1%). The most active beneficials were Necremnus tutae and Neochrysocharis formosa in protected and open-field crops, respectively. The tomato leafminer completed 6 generations in the greenhouse tomato crop during the winter-spring growing season, whereas in open-field crops the pest completed two generations on winter potato and 4-5 in spring-summer tomato. The degree-day model based on minimum and maximum temperatures reliably described the population dynamics in the protected crop, and estimated the completion of 7.4 generations per year under open-field Mediterranean conditions.

Insecticidal efficacy and persistence of a co-occluded binary mixture of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) variants in protected and field-grown tomato crops on the Iberian Peninsula.

A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. Concentrations of 10(9) -10(11) occlusion bodies (OBs) L(-1) of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 10(10) OBs L(-1) of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry.

Testing basil as banker plant in IPM greenhouse tomato crops

In order to reduce the use of pesticides, banker plants may be added to crop systems. They can improve the presence of predatory arthropods by offering shelter or alternative food. In the present study, we analyzed basil as banker plant in a greenhouse IPM tomato crop system testing different plant combinations in monocultures vs. dicultures. We measured the influence of the presence of basil on the reduction of pest number, predator population stability, plant health and crop yield. Significantly fewer pests were present in dicultures when basil was present, but the number of predators, crop yield and leaf health was not statistically different between plant combinations. Under the given conditions, basil could not be categorized as an efficient banker plant for Macrolophus pygmaeus.

Spray distribution evaluation of different settings of a hand-held-trolley sprayer used in greenhouse tomato crops.

Hand-held-trolley sprayers have recently been promoted to improve spray application techniques in greenhouses in south-eastern Spain. However, certain aspects remain to be improved. A modified hand-held-trolley sprayer was evaluated under two different canopy conditions (high and low canopy density) and with several sprayer settings (nozzle type, air assistance and spray volume). In this study, the deposition, coverage and uniformity of distribution of the spray on the canopy have been assessed. The deposition on leaves was significantly higher when flat-fan nozzles and air assistance were used at both high and low spray volumes. No differences were detected between the reference system at a high spray volume and the modified trolley at a low spray volume. Flat-fan nozzles with air assistance increased penetrability into the canopy. Air assistance and flat-fan nozzles allow volume rates to be reduced while maintaining or improving spray quality distribution. The working parameters of hand-held sprayers must be considered to reduce environmental risk and increase the efficacy of the spraying process. © 2015 Society of Chemical Industry.

Overwintering potential of the invasive leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) as a pest in greenhouse tomato production in Western Europe

The South American tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest in tomato crops. After having spread rapidly in the Mediterranean area since its first detection in 2006, it has recently become established in greenhouses in Western Europe. It was assumed that the low temperatures commonly associated with the winters in this area would prevent this exotic species from successful overwintering. However, the observed presence of T. absoluta at the start of the growing season in Belgium sparked a study on its potential to overwinter in Western Europe. In this study, the insect’s cold hardiness and overwintering potential was assessed by determining: (1) the supercooling point (SCP) of larvae, pupae, and adults, (2) the lower lethal time (LT) for these stages at 0 and 5 °C, and (3) the reproductive diapause incidence, as indicated by the reproductive performance of females reared at two temperatures (18 and 25 °C) and two photoperiods [16:8 and 8:16 (L:D) h]. The mean SCP recorded for pupae (−16.7 °C) was significantly higher than for adults (−17.8 °C) and larvae (−18.2 °C). Based on estimates of the LT adults demonstrated better cold hardiness than larvae and pupae at both 0 and 5 °C with the median LT of adults averaging 17.9 and 27.2 days, respectively. No reproductive diapause was observed under the tested regimes. The results of this study indicate that T. absoluta is likely to successfully overwinter between two successive tomato crops in commercial greenhouses in Western Europe.

First Report of Tomato chlorosis virus (ToCV) in Tomato Crops in Saudi Arabia

During January 2014, open field and greenhouse tomato (Solanum lycopersicum L.) crops in the peripheral areas of Riyadh region (Al-Aflaj, Al-Kharj, Al-Waseel, and Al-Dalam), Saudi Arabia, were surveyed. In all surveyed tomato crops, yellowing symptoms were observed on the lower leaves, possibly infected by a whitefly transmitted crinivirus (family Closteroviridae) such as Tomato chlorosis virus (ToCV) and/or Tomato infectious chlorosis virus (TICV). Dense population of whiteflies (Bemisia tabaci G.) were present in all affected plants. Incidence of the yellowing disease varied between four greenhouses and three open field tomato crops, but in the majority of the tomato crops surveyed, symptoms typical of Begomovirus infection such as severe stunting, degeneration, upward cupping, distortion and interveinal yellowing of upper leaves, and flower abortion were also observed. Tomato yellow leaf curl virus (TYLCV) is endemic in Saudi Arabia causing severe crop losses (1). Twenty-six leaf samples from 24 symptomatic and two asymptomatic plants from four fields (three greenhouses and one open field crop) were collected and were processed in the lab at King Saud University. Whitefly transmission on tomato indicator plants was carried out using B. tabaci to fulfill Koch's postulates. Two hundred virus-free B. tabaci adults were confined to one of the collected symptomatic tomato sample singly infected with ToCV for a 48-h acquisition access period, followed by a 48-h inoculation access period on five healthy tomato plants Hybrid Super Strain B, using 40 whiteflies per plant. Crinivirus detection following transmission was conducted by RT-PCR. Total RNA was extracted from 26 collected leaf samples using the Total RNA Purification Kit and analyzed by SCRIPT One-Step RT-PCR Kit (Jena Bioscience). First, the degenerate primers HS-11/HS12 were used for amplification of a 587-bp fragment of the HSP70 gene of ToCV and TICV (3). Second, the RT-PCR product was subjected to a nested PCR using specific primers TIC-3/TIC-4 and TOC-5/TOC-6, for the detection of both TICV and ToCV, respectively (2). Finally, degenerate primers (AV494/AC1048) were used for detection of begomoviruses (4). No fragment was amplified by TIC-3/TIC-4 primer whereas TOC-5/TOC-6 amplified a size of 463 bp in all 24 symptomatic tested samples, including one mixed infection with TYLCV detected by AV494/AC1048. Asymptomatic samples did not produce any amplicon regarding TICV, ToCV, and Begomovirus detection. The amplicons of four positive fragments, each from one field, were further sequenced in both directions and all obtained sequences (KJ433488, KJ433489, KJ433490, and KJ433491) analyzed with BLAST and revealed 99% identity with the most closely deposited sequences in NCBI from Japan (AB513442) and Brazil (JQ952601). In the transmission tests, ToCV was detected to all tomato indicator plants which revealed yellowing symptoms 6 weeks post inoculation, whereas no transmission was obtained when non-viruliferous whitefly adults fed on two asymptomatic tomato leaves. To our knowledge, this is the first report of ToCV infecting tomato crops in Saudi Arabia. Further studies are being carried out to study epidemiology and genetic diversity of this virus associated with yellowing diseases of tomato in different regions of Saudi Arabia. This finding is important for the tomato crops and possibly other virus hosts as may cause serious epidemics and crop losses.

Water content virtual sensor for tomatoes in coconut coir substrate for irrigation control design

The main objective of this work has been the development of a virtual sensor (VS) based on the water balance dynamics of tomato crops in greenhouses, using coconut coir substrate as an example in this case. Such sensors are used to provide a viable and economical alternative to expensive or impractical sensors. The final virtual sensor is the result of combining: crop growth, where the water is distributed in structural and non-structural plant biomass (storage); the substrate, which is considered to be composed of a single layer; and the water loss caused by transpiration and drainage. In this work, two ECH2O-EC-5 sensors (Decagon Devices) were calibrated and then used to determine the substrate water content; and a microlysimeter was installed to continuously sample the water supplied, the drainage, and the crop water loss values. The VS took into account the water supplied, the amount of water in three stores (the substrate, the root, and the aerial part of the crop), the climate, and the water loss. The water dynamic was determined by system identification techniques and by physical virtual sensors, which considered the water balance from a holistic point of view – as a sub-model for a customizable interface between crop growth and the plant ecosystem. The influence of both the crop and the climate conditions on the water balance was analysed and the virtual sensors were evaluated giving good final results.

Report of A Larval Parasitoid of Tuta Absoluta (Meyrick) (Lepidoptera: Gelechiidae) from Iran

Abstract The tomato leafminer Tuta absoluta (Meyrick) is one of the most devastating pests of greenhouse and outdoor tomato crops. Since it is a newly introduced pest in Iran, there is an important need to search for its natural enemies. In the course of a survey on the natural enemies of this pest, samplings were carried out in tomato greenhouses heavily infested with the tomato leafminer, in the Borazjan region of the Bushehr province in Iran. Leaves with mines were reared in the laboratory until emergence of parasitoids. A single parasitoid species of the family Eulophidae was reared and identified as Neochrysocharis formosus (Westwood 1833). This species is reported for the first time on the tomato leafminer in Iran. Such information may help in developing biological control programs to control this serious pest.

Dynamic modeling of mineral contents in greenhouse tomato crop

Tomato is one the most important vegetables worldwide and mineral nutrition in tomato crops is considered as the second most important factor in crop management after water availability. Mathematical modeling techniques allow us to design strategies for nutrition management. In order to generate the necessary information to validate and calibrate a dynamic growth model, two tomato crop cycles were developed. Several mineral analyses were performed during crop development to determine the behavior of N, P, K, Ca, Mg and S in different organs of the plant. Regression models were generated to mimic the behavior of minerals in tomato plants and they were included in the model in order to simulate their dynamic behavior. The results of this experiments showed that the growth model adequately simulates leaf and fruit weight (EF > 0.95 and Index > 0.95). As for harvested fruits and harvested leaves, the simulation was less efficient (EF

Estimation of the water requirements of greenhouse tomato crop using multiple regression models

Water utilization by crops, namely tomato, within greenhouses is one of the most significant factors in determining yield. Daily water consumption by tomato plants were calculated, to determine the actual evapotranspiration and transpiration rates, as well as the incorporation measurement of climatic variables and weekly determinations of fresh and dry weights of the plants. Estimations of daily evapotranspiration and transpiration rates by the tomato plants were calculated using multiple regression models. The best models for estimating, both the evapotranspiration and transpiration, had adjusted R 2 values greater than 0.9. Using the multiple obtained regression models it is possible to estimate the water needs of tomato plants under greenhouse conditions from readily available variables. The aim of this study was to generate regression models in order to determine the crop water requirements of greenhouse tomato.

Volume application rate adapted to the canopy size in greenhouse tomato crops

The application rate of plant-protection products is indicated as a concentration or amount of product per area. Greenhouse crops grow swiftly, and an application rate based on a fixed amount of product per hectare can result either in large losses and overdoses when the plants are small or to be insufficient when the plants are fully developed. To solve these problems, the application rates of plant-protection products need to be adapted to the plant mass present in the greenhouse when the spray is applied. Two models were developed to estimate the leaf area based on easily measured geometric data of the vegetation in a greenhouse tomato crop. The model based on the PRV (Plant Row Volume) had that best results. The calculation of the volume application rate from the PRV has resulted in a reduction of more than 30 % of the quantity of plant protection product sprayed, without decreasing yield. The PRV of a greenhouse tomato (Lycopersicon esculentum Mill.) is an easily measured parameter that enables the estimation of the leaf area index and the use of application strategies adapted to the changes in the plant canopy, saving major amounts of plant protection product used, compared to the conventional system.

Evaluation of the effect of spray pressure in hand-held sprayers in a greenhouse tomato crop

In greenhouses, plant-protection products are usually applied by hand-held high-pressure spray guns or lances spraying at high volume rates. This low-technology equipment produces a deposit distribution of low uniformity on the plant canopy, heavy losses to the soil, and high exposure risk to workers. The aim of the present work was to evaluate the effect of spray pressure on deposition and losses to the ground using a hand-held spray lance in a greenhouse tomato crop. Spray applications were made at three different pressures (1000 kPa, 1500 kPa and 2000 kPa) in two developmental stages of a tomato crop. The results show that for the applications at the highest pressure, the average deposit was between 22.5% and 34.6% less than at the two lower pressures. Also, the use of high pressures such as 2000 kPa hampered penetration into the plant canopy, with deposition values in the inner zones of the canopy of between 9.4% and 37.4% less than when pressures of 1000 kPa and 1500 kPa were used. Nevertheless, the losses to the ground for the highest pressure were between 10.3% and 24% lower than for the two lower pressures.

Availability of phosphorus in greenhouse cropping systems with tomatoes – influence of soil and citric acid

Analyses of plant sap from organic greenhouse tomato crops show that the levels of phosphorus (P) are frequently low, despite the fact that soil analyses indicate P status in the soil to be good. In the present study, two soils (A and B) with a pH of just over 6 and a high total content of N and P were investigated with respect to release of P and uptake in a tomato crop. The fertilisers primarily used on soil A was silage and blood meal, and on soil B Vinasse and blood meal. An incubation experiment showed that the release of P per unit time was greater from soil A than soil B. This difference between the two soils may be due to lower soil organic matter concentration, with less P sorbed by Al and Fe on soil A, and a fertiliser regime which favours a high concentration of dissolved organic carbon in this soil. Tomato plants grown for 10 weeks in the soils had greater DW production, total uptake of P and concentration of P in the leaves on soil A than on soil B. Addition of citric acid to the soils in order to mobilise P increased plant yield and uptake of N and P on soil A. Despite the increased growth, the concentration of P in plant leaves increased and the N concentration was unchanged. On soil B addition of citric acid decreased Zn uptake in the tomato plants despite good availability, resulting in a lower concentration of this micronutrient in the leaves. The plants on soil A maintained their concentrations of all micronutrients analysed, but the ratio of P to micronutrients increased. Thus for commercial organic tomato growers, adding citric acid with the irrigation water offers a possibility to increase P availability.

Potential for combined use of parasitoids and generalist predators for biological control of the key invasive tomato pest Tuta absoluta

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has recently invaded Mediterranean countries and is a major pest in tomato crops. Trichogrammatid oophagous parasitoids have shown promising potential for controlling the pest before the yield decreases in the greenhouse. In protected tomato crops (greenhouse), mirid predators are commonly used for biological control of whiteflies and they also prey on T. absoluta. These predators do not attack Trichogramma adults but they may partially decrease the overall impact of parasitoids on T. absoluta if intraguild predation (IGP) occurs on parasitized eggs. Under laboratory conditions, we tested if the mirid predator Macrolophus pygmaeus shows preference between parasitized and unparasitized T. absoluta eggs. We also tested if the predator reduces the number of parasitized eggs on caged tomato plants (microcosms) and assessed the efficacy of natural enemies used alone or together in limiting T. absoluta populations. We found that IGP is inflicted on the parasitoid Trichogramma achaeae by M. pygmaeus and that the risk of IGP depends on the developmental stage of T. achaeae inside the egg because the larva is at risk mostly early in its development (when parasitized egg is still yellow). In addition, we observed that non-consumptive events, likely probing of the predator on parasitized eggs, may induce mortality in parasitoid offspring without actual feeding on parasitized eggs. However, both IGP and non-consumptive events decreased when the predator was not confined with parasitized eggs in small arenas. Despite negative effects of the predator to the parasitoid, results demonstrate that adding Trichogramma parasitoids may significantly increase the level of control of the pest over what could be attained when only the mirid predator M. pygmaeus is present on tomato. Implications of results are discussed regarding potential of these natural enemies for biological control of T. absoluta in greenhouse tomato crops.

Evaluation of a fog cooling system for applying plant-protection products in a greenhouse tomato crop

The hand-held high-volume spray techniques used to apply plant-protection products in glasshouses in south-eastern Spain have poor efficiency due to heavy losses to the soil and to high risks of worker exposure. Therefore, it is necessary to develop alternative techniques to reduce these problems. The main objective of fog cooling systems is to control the climate inside the greenhouse, but the possibility of adding the extra function of plant protection without the presence of an operator inside the greenhouse, thereby accelerating the payback on the investment in equipment, has stirred interest among farmers. In the present study, the capabilities of fog cooling system were investigated in comparison with conventional spray guns. The results show that the deposition values on the crop were very low, far below the values reached with spray guns. Also, losses increased, due mainly to evaporation of droplets, despite saturating the atmosphere of the greenhouse before applications. The need to saturate the atmosphere implying an expense in water that is not necessary with spray guns.

Recycling of environmentally problematic plant wastes generated from greenhouse tomato crops through vermicomposting

The enormous quantity of plant waste produced from greenhouse tomato crops is an environmental problem that should be solved by recycling that waste into valuable organic products through low-cost technologies, such as vermicomposting. Feasibility of vermicomposting greenhouse tomato-plant waste (P) using paper-mill sludge (S) as complementary waste was investigated by this study. Earthworm development in P, S, and two mixtures of both wastes was monitored over 24 weeks and compared with that in cow dung (D), an optimum organic-waste to be vermicomposted. The effectiveness of vermicomposting to biostabilize those wastes was assessed by analysing phospholipid fatty acid composition, chemical features, plant-nutrient content, metal concentration, enzyme activities, and germination index (GI). A commercial vermicompost was also analyzed and taken as a reference of vermicompost quality. Earthworms did not survive in P alone, but a mixture of P with S at a ratio of 2:1 or 1:1 resulted in earthworm development similar to that observed in D. Phospholipid fatty acid analysis revealed that earthworm activity strongly transformed initial microbiota inhabiting the wastes, giving rise to vermicompost microbial communities which were similar to that of a commercial vermicompost. Both mixtures of P and S were properly biostabilized through vermicomposting, as indicated by decreases in their C:N ratio and enzyme activities together with increases in their degree of maturity (GI ~ 100 %) after the process. This study demonstrates that the vermicomposting of tomato-plant waste together with paper-mill sludge allows the recycling of both wastes, thereby improving the environmental sustainability of greenhouse crops.

An environmental impact calculator for greenhouse production systems

Multiple web-based calculators have come on the market as tools to support sustainable decision making, but few are available to agriculture. Life cycle assessment (LCA) has proved to be an objective, transparent tool for calculating environmental impacts throughout the life cycle of products and services, but can often be too complex for non-specialists. The objective of this study was therefore to develop an environmental support tool to determine the environmental impacts of protected crops. An effort was made to provide an easy-to-use tool in order to reach a wide audience and help horticulture stakeholders choose efficient options to mitigate the environmental impacts of protected crops. Users can estimate the environmental performance of their crops by entering a limited amount of data and following a few easy steps. A questionnaire must be answered with data on the crop, greenhouse dimensions, substrate, waste management, and the consumption of water, energy, fertilisers and pesticides. The calculator was designed as a simplified LCA, based on two scenarios analysed in detail in previous tasks of the EUPHOROS project and used as reference systems in this study. Two spreadsheets were provided based on these reference scenarios: one for a tomato crop in a multi-tunnel greenhouse under Southern European climate conditions and the other for a tomato crop in a Venlo glass greenhouse under Central European climate conditions. The selected functional unit was one tonne of tomatoes. Default data were given for each reference system for users who did not have complete specific data and to provide results for comparison with users' own results.The results were presented for water use as an inventory indicator and for the impact categories abiotic depletion, acidification, eutrophication, global warming, photochemical oxidation and cumulative energy demand. In the multi-tunnel greenhouse, the main contributors based on the default data were the structure, fertilisers and auxiliary equipment, whereas, for the Venlo glass greenhouse, the main contributors were energy consumption for heating and, to a lesser extent, the structure. The results were evaluated for alternative options of electricity, fertilisers, pesticides and means of transport, as these areas were found to have potential variability, depending on the characterisation model and datasets used.The resulting calculator is a useful tool to simulate the environmental performance of protected horticultural production systems and is also helpful to growers and advisers for evaluating the efficiency of input reduction options.