Greenhouse Production Systems Research Articles

Design and Implementation of a Low-Cost, Linear Robotic Camera System, Targeting Greenhouse Plant Growth Monitoring

Automated greenhouse production systems frequently employ non-destructive techniques, such as computer vision-based methods, to accurately measure plant physiological properties and monitor crop growth. By utilizing an automated image acquisition and analysis system, it becomes possible to swiftly assess the growth and health of plants throughout their entire lifecycle. This valuable information can be utilized by growers, farmers, and crop researchers who are interested in self-cultivation procedures. At the same time, such a system can alleviate the burden of daily plant photography for human photographers and crop researchers, while facilitating automated plant image acquisition for crop status monitoring. Given these considerations, the aim of this study was to develop an experimental, low-cost, 1-DOF linear robotic camera system specifically designed for automated plant photography. As an initial evaluation of the proposed system, which targets future research endeavors of simplifying the process of plant growth monitoring in a small greenhouse, the experimental setup and precise plant identification and localization are demonstrated in this work through an application on lettuce plants, imaged mostly under laboratory conditions.

Early assessment of fungal and oomycete pathogens in greenhouse irrigation water using Oxford nanopore amplicon sequencing.

Water-borne plant pathogenic fungi and oomycetes are a major threat in greenhouse production systems. Early detection and quantification of these pathogens would enable us to ascertain both economic and biological thresholds required for a timely treatment, thus improving effective disease management. Here, we used Oxford nanopore MinION amplicon sequencing to analyze microbial communities in irrigation water collected from greenhouses used for growing tomato, cucumber and Aeschynanthus sp. Fungal and oomycete communities were characterized using primers that amplify the full internal transcribed spacer (ITS) region. To assess the sensitivity of the MinION sequencing, we spiked serially diluted mock DNA into the DNA isolated from greenhouse water samples prior to library preparation. Relative abundances of fungal and oomycete reads were distinct in the greenhouse irrigation water samples and in water samples from setups with tomato that was inoculated with Fusarium oxysporum. Sequence reads derived from fungal and oomycete mock communities were proportionate in the respective serial dilution samples, thus confirming the suitability of MinION amplicon sequencing for environmental monitoring. By using spike-ins as standards to test the reliability of quantification using the MinION, we found that the detection of spike-ins was highly affected by the background quantities of fungal or oomycete DNA in the sample. We observed that spike-ins having shorter length (538bp) produced reads across most of our dilutions compared to the longer spikes (>790bp). Moreover, the sequence reads were uneven with respect to dilution series and were least retrievable in the background samples having the highest DNA concentration, suggesting a narrow dynamic range of performance. We suggest continuous benchmarking of the MinION sequencing to improve quantitative metabarcoding efforts for rapid plant disease diagnostic and monitoring in the future.

Chance-constrained stochastic MPC of greenhouse production systems with parametric uncertainty

Greenhouse climate control is important to provide sufficient fresh food for the growing population in an economical and sustainable manner. However, the developed crop-climate models are generally complex with parametric uncertainties and far from describing the real system accurately, which affects adversely the control system’s performance. To improve optimality and guarantee robustness during the control process, we develop and implement a stochastic model predictive control (MPC) scheme for greenhouse production systems considering parametric uncertainties. By leveraging the advantages of model linearization, the proposed chance-constrained MPC method enables a more straightforward formulation of uncertainty constraints and computationally cheaper optimization in comparison to directly using the nonlinear model. Finally, the efficacy of the proposed approach is demonstrated on a greenhouse climate control case study.

Imaging spectroscopy for monitoring the crop status of tomato plants

The increasing complexity of greenhouse production systems requires the step to a more data-driven approach that is based on robust, intelligent sensors. Whereas climate sensors are widely available in greenhouse systems, control based on crop data is still in its infancy. There is a clear need among growers to monitor the status of the crop in the greenhouse in real time and non-destructively compared to current practice of cumbersome, expensive and slow laboratory measurements. This project aimed to use visible and near infrared imaging spectroscopy to determine the contents of sugars and starch, dry matter percentage, chlorophyll, and nutrient composition in both leaves and fruits of tomato plants. The results were promising, with Q2 values up to 0.97 for dry matter content in leaves, 0.86 for sugar and 0.99 for chlorophyll-a. The results also showed that pigments have a better correlation to the visible spectrum, while water content, sugars and nutrients showed a better correlation in the near infrared part of the spectrum.

Evaluation of sustainability in strawberry crops production under greenhouse and open-field systems in the Andes

ABSTRACTThe use of natural resources for food production and the identification of viable solutions to problems related to agricultural sustainability are topics of current debate. Our proposed objectives were to: i) determine the agronomic characteristics of strawberry crops in open-field and aeroponic greenhouse production systems, ii) assess the sustainability of production systems concerning social, environmental, economic, and governance dimensions, and iii) identify the variability of sustainability scores between production systems. Surveys were conducted on small Mestizo strawberry producers with open-field production systems and aeroponic production researchers in the Ecuadorian Andes. The SAFA-FAO methodology was applied, considering 111 indicators, 56 subtopics, and 20 topics, distributed among the four dimensions. A principal component analysis was performed using the Infostat programme. The sustainability score (0–5) of the aeroponic system was 1.09 times higher than that of the traditional system. The dimensions of economic resilience (2.23) and good governance (2.29) obtained low scores in the open-field system, and in the aeroponic production system the dimensions with high scores were environmental integrity (4.05) and social welfare (4.46). The identified sustainability dynamics contribute to a better multidimensional understanding for decision-makers and are a contribution toward meeting the goals of the UN’s 2030 Agenda.

Prescriptive-Corrective Irrigation and Macronutrient Management in Greenhouse Soil-Grown Tomato Using the VegSyst-DSS v2 Decision Support Tool

This work relates to greenhouse vegetable production in soil in Almeria, Spain. The prescriptive–corrective management (PCM) of irrigation and fertilization (N, P, K, Ca, and Mg) was evaluated. PCM combined recommendations (prescriptive management) for irrigation and nutrients made with the VegSyst-DSS v2, a decision support system, with monitoring (corrective management) using tensiometers (for irrigation) and petiole sap analysis (for nutrients). PCM was compared with conventional farmer management (CONV). The VegSyst-DSS v2 recommends applied nutrient concentrations considering simulated crop uptake, available soil nutrient supply, and evapotranspiration (ETc). This study was conducted with soil-grown tomato in a plastic greenhouse. Nutrients were applied in nutrient solution via drip fertigation. Compared to CONV management, PCM reduced irrigation by 25%, N, K, and Mg application by 40%, Ca by 58%, and P by 85%. There were no significant differences between treatments in fruit production and quality, despite appreciable reductions in irrigation and nutrient application. An economic analysis indicated that in this 7-month tomato crop, PCM compared to CONV management was associated with a financial saving of 1611 € ha−1. These results showed that by using prescriptive–corrective fertigation management, based on the VegSyst-DSS v2, considerable savings can be achieved in water and nutrient (N, P, K, Ca, and Mg) inputs to greenhouse tomato without compromising production. This can reduce farmer costs and the environmental impact associated with these greenhouse production systems.

Are Entomopathogenic Fungal-based Insecticides and Insect Growth Regulator Mixtures Effective Against the Citrus Mealybug, Planococcus citri (Hemiptera: Pseudococcidae), Feeding on Coleus, Solenostemon scutellarioides, Plants under Greenhouse Conditions?

The citrus mealybug, Planococcus citri, is an insect pest of greenhouse-grown horticultural crops. Citrus mealybug causes plant damage when feeding on plant leaves, stems, flowers, and fruits, resulting in a substantial economic loss. Insecticides are applied to manage citrus mealybug populations in greenhouse production systems. Anecdotal information suggests that mixing entomopathogenic fungal-based insecticides with insect growth regulators may be effective for managing citrus mealybug populations under greenhouse conditions. Consequently, we conducted two experiments in a research greenhouse at Kansas State University (Manhattan, KS, USA) in 2023. The experiments were designed to determine the efficacy of three commercially available entomopathogenic fungal-based insecticides [Beauveria bassiana Strain GHA (BotaniGard®), B. bassiana strain PPRI 5339 (Velifer™) and Isaria fumosorosea Apopka Strain 97 (Ancora®)] when mixed with three insect growth regulators [azadirachtin (Azatin® O), novaluron (Pedestal®), and pyriproxyfen (Distance®)] on citrus mealybug feeding on coleus, Solenostemon scutellarioides, plants. The entomopathogenic fungal-based insecticides alone or when mixed with the insect growth regulators were not effective in managing citrus mealybug populations, with <20% mortality during each experiment. In addition, all coleus plants treated with the entomopathogenic fungal-based insecticides had a white, powdery residue on the leaves. Our study demonstrates that entomopathogenic fungal-based insecticides, even when mixed with insect growth regulators, are not effective in managing citrus mealybug populations in greenhouses, which is likely because the environmental conditions (temperature and relative humidity) are not optimal for conidial germination and hyphal infection to occur. Therefore, entomopathogenic fungal-based insecticides have limited use for managing insect pests in greenhouse production systems.

Impact of Agricultural Policies on the Sustainable Greenhouse Development in Biskra Region (Algeria)

Since its appearance in Algerian agriculture, the greenhouse production system has turned the agricultural sector upside down, bringing great advantages for production in terms of quality and quantity, creating a very important socio-economic dynamic, especially in the Saharan region. This paper makes a new contribution by providing information on the impact of agricultural policies on greenhouse development in Biskra (southeastern city in Algeria). This study aims to understand the type of farms/farmers most specialized in greenhouses as well as the relationship between the use of these land acquisition and financing policies (PNDA) and their degree of specialization in greenhouses. A field survey was held from February to April 2021 in the M’ziraa region (a municipality of Biskra City), completing 97 questionnaires. Collected data were analysed by Ordinary Least Squares (OLS) regression and Truncated regression. The results show that farmers who used PNDA to acquire the land and for greenhouse investments and those with a lower education level are less likely to specialize in greenhouse production. Similarly, the effect of farm size is negative on the specialization in greenhouse production. Conversely, we found that farmers who do not directly manage the farm and those who have a longer experience with greenhouse production invest a higher share of their land in greenhouses.

The Use of Silicon Substrate Amendments to Decrease Micronutrient Concentrations at Varying Micronutrient Fertility Rates with Cannabis sativa ‘Auto CBG’

Many abiotic factors impact the yield and growth of Cannabis sativa (cannabis). Cannabis has been reported to be a bio-accumulator of heavy metals. For growers who are targeting floral production and other byproducts for human consumption, this is a concern. Silicon (Si) has been examined as a beneficial plant element to limit the uptake of heavy metals in a variety of crops. The objective of this study was to determine the impact of Si on heavy metal micronutrient uptake and plant growth for greenhouse-cultivated cannabis at varying Si substrate amendments. ‘Auto CBG’ plants were grown in a 70:30 peat:perlite substrate with one of three varying calcium silicate (CaSiO3) (Si) substrate amendment rates, Si0X, Si0.5X, or Si1X (of 0.0, 1.04, and 2.07 kg⋅m−3 CaSiO3), and one of three micronutrient fertility treatments, M1X [0.49 boron (B), 0.19 copper (Cu), 4.02 iron (Fe), 0.99 manganese (Mn), 0.01 molybdenum (Mo), and 0.20 zinc (Zn) mg⋅L−1], M2X, or M4X, using a modified Hoagland’s solution, creating a 3 × 3 factorial. Plants grown with a Si1X substrate amendment exhibited a significantly lower iron concentration in the foliage and root tissue when compared with those grown in a substrate without Si. After 6 weeks of growth, Si0X plants that received a M4X fertility rate exhibited greater foliar micronutrient concentrations of B, Mn, Zn, Fe, and Cu than plants that received a Si substrate amendment when provided a M4X fertility rate. Additionally, lower micronutrient concentrations in floral tissue were observed in plants that received a Si substrate amendment for M2X and M4X when compared with plants that did not. Silicon substrate amendments had no impact on the cannabinoid concentration or plant growth metrics after 12 weeks of growth. This research suggests that using a Si substrate amendment in a greenhouse production system can limit excessive uptake and accumulation of micronutrients in the foliage, roots, and floral material of cannabis without negative impacts on plant growth or cannabinoid concentrations.

Performance of Entomopathogenic Fungal-Based Insecticides against the Citrus Mealybug (Hemiptera: Pseudococcidae) on Coleus (Lamiales: Lamiaceae) Plants under Greenhouse Conditions1

Abstract The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is an important insect pest of greenhouse-grown horticultural crops. Citrus mealybug causes direct plant damage when feeding on plant leaves, stems, flowers, and fruits, and this damage can result in substantial economic losses. Insecticides are used to manage citrus mealybug populations in greenhouse production systems. Although entomopathogenic fungal-based insecticides are labeled for use against citrus mealybug, there is no quantitative information on their efficacy against this insect pest under greenhouse conditions. Consequently, four experiments were conducted in a research greenhouse at Kansas State University (Manhattan) from 2020 to 2022 to determine the efficacy of three commercially available entomopathogenic fungal-based insecticides on citrus mealybug feeding on coleus, Solenostemon scutellarioides (L.) Codd (Lamiales: Lamiaceae), plants: Beauveria bassiana strain GHA (BotaniGard®, Laverlam International Corp., Butte, MT), B. bassiana strain PPRI 5339 (Velifer™, BASF, Research Triangle, NC), and Isaria fumosorosea Apopka strain 97 (Ancora®, OHP, Inc., Bluffton, SC). The surfactant polyether and polyether-polymethylsiloxane-copolymer (CapSil®, Aquatrols, Paulsboro, NJ) was added to spray solutions to determine whether the surfactant would enhance efficacy. The entomopathogenic fungal-based insecticides, with or without the surfactant, were not effective in managing citrus mealybug populations, with <50% mortality in all four experiments. Our study indicates that entomopathogenic fungal-based insecticides are not effective in managing citrus mealybug populations in greenhouses.

Energy Analysis for Two Production Systems of Cucumber

This research, conducted in Gotvand, southwest of Iran, compared the energy consumption of two cucumber production systems: field and greenhouse production systems. In this study, energy inputs of two production systems of cucumber (including seed, pesticide, human labor, machinery, diesel fuel, electricity, organic manure, chemical fertilizer) were determined from questionnaires completed by farmers. The results of the experiment indicated that the energy input of the two cultivation systems was not significantly different in input energies. In both cucumber production systems, the most input energy was allocated to nitrogen fertilizer (57% and 53% for field and greenhouse, respectively) followed by diesel fuel (21% in both production systems). Non-renewable energies accounted for 90 and 88% of the total energy input to the farm and greenhouse systems, respectively. Total output energy of field and greenhouse cucumber production system was 33000 and 34000 MJ, respectively. Reducing the consumption of nitrogen fertilizer through the use of appropriate crop rotation is a suitable solution to improve energy efficiency in the cucumber production system.

Evaluation of a Proprietary Plant Extract to Suppress Bacterial Canker and Improve Yield in Hydroponic Tomatoes

Bacterial canker of tomato, caused by the systemic bacterial phytopathogen Clavibacter michiganensis, can result in significant economic losses in hydroponic tomato production systems. Lacking effective bactericides, the disease is managed primarily by clean seed procedures, sanitation, and quarantine. Plant extracts have been shown to display antimicrobial activity and/or induce plant resistance to disease. We tested the efficacy of AOMMA-Agro, an Organic Materials Review Institute-listed proprietary blend of plant extracts, in suppressing bacterial canker and improving yield and shelf life in hydroponic tomato trials over 2 years. Experiments were conducted in a greenhouse with ‘Campari’ tomatoes transplanted into coconut coir blocks and grown under hydroponic conditions. Plants were trellised, pruned, and harvested according to commercial standards. AOMMA-Agro was applied weekly or biweekly as a foliar spray and inoculated with C. michiganensis. Plants treated with water and inoculated or not inoculated served as controls. Disease severity was relatively low in both years; however, disease progress was significantly lower for plants inoculated and treated biweekly, but not weekly, with AOMMA-Agro than for nontreated, noninoculated plants in one of two trials. Similar results were observed for C. michiganensis incidence determined using qPCR. Marketable yield was 29 and 44% higher from inoculated plants treated biweekly with AOMMA-Agro than from nontreated, noninoculated plants in the two experiments. These results support the use of AOMMA-Agro as a potential option for bacterial canker management and yield enhancement in hydroponic tomato greenhouse production systems.

Evaluation of annual and herbaceous perennial plants for susceptibility to Phytophthora root and crown rot in the Southeastern United States

Abstract Annual and herbaceous perennial ornamental bedding plants are popular, high value crops in the southeastern United States. However, many of these plants are subject to root or crown rot caused by Phytophthora species. In North Carolina, Phytophthora nicotianae Breda de Haan, Phytophthora drechsleri Tucker, Phytophthora cryptogea Pethybr. & Laff., and/or Phytophthora tropicalis Aragakia and J.Y. Uchida cause this disease in greenhouse production systems and in the landscape. Because practical management options for landscapers and homeowners are limited, the objective of this study was to identify annual and herbaceous perennial ornamental landscape plants that perform well in Phytophthora-infested landscape beds at three locations in western and central North Carolina. Although landscape beds were artificially inoculated with P. nicotianae, P. drechsleri, P. cryptogea sensu lato, and P. tropicalis, P. nicotianae was the most frequently isolated species from symptomatic plants and was the only species confirmed to be active at all locations in both years of this study. Eighteen cultivars of annuals and twenty-one cultivars of herbaceous perennials performed well and have been recommended for Phytophthora-infested landscapes to growers and homeowners in the southeastern United States.

Survival of Rove Beetle, Dalotia coriaria (Coleoptera: Staphylinidae), and Insidious Flower Bug, Orius insidiosus (Hemiptera: Anthocoridae), Adults after Exposure to Five Newly Registered Insecticides under Laboratory Conditions

The rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), and insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), are biological control agents used in greenhouse production systems. However, there is no information available on the effects of five newly registered insecticides: pyrethrins and canola oil, cyclaniliprole, cyclaniliprole and flonicamid, afidopyropen, and Beauveria bassiana PPRI 5339 on adult survival of these biological control agents. Consequently, two experiments were conducted under laboratory conditions in 2020 to determine the direct effects of the five insecticides on rove beetle and insidious flower bug adults. Individual rove beetle or insidious flower bug adults were placed into Petri dishes with filter paper treated with the insecticides. After 24, 48, 72, and 96 hours, the number of live and dead adults was recorded. We found that afidopyropen at 0.27 mL/500 mL and Beauveria bassiana PPRI 5339 at 0.11 and 0.50 mL/500 mL, were not directly harmful to rove beetle or insidious flower bug adults with 100% survival. However, pyrethrins and canola oil, cyclaniliprole, and cyclaniliprole and flonicamid were directly harmful to rove beetles and insidious flower bugs with ≤ 60% adult survival. Based on our results, afidopyropen and Beauveria bassiana PPRI 5339 can be integrated into biological control programs that include the use of rove beetle or insidious flower bug adults.

Large differences in ammonia emission factors between greenhouse and open-field systems under different practices across Chinese vegetable cultivation

Estimating ammonia (NH3) emission factors (EFs) for vegetable production can support assessment of potential atmospheric pollution risk and provide information for mitigating NH3 volatilization. The EFs in greenhouse and open-field systems under different fertilization, irrigation regimes, vegetable types and soil properties in both greenhouse and open-field vegetable production systems in China are poorly understood. An integrated analysis was performed, including 282 field measurements of NH3 volatilization from 54 field studies, to quantify ammonia EFs under different management practices and soil properties. The results showed that the mean ammonia EF across all measurements was 4.2 % (3.6 %–4.8 %). The EFs of greenhouse and open-field systems were 2.0 % (1.5 %–2.5 %) and 6.3 % (5.4 %–7.2 %), respectively. There was a power function relationship between nitrogen application rate and ammonia EF in greenhouses. No relationship was identified between nitrogen application rate and ammonia EF in the open-field system. The EFs of organic fertilizers were lower than those of both chemical fertilizers and the combination of chemical and organic fertilizers. EFs of leafy vegetables, cabbages, solanaceous vegetables and melons were 2.7 %, 2.9 %, 1.4 % and 1.4 % in the greenhouse system, and 5.2 %, 5.7 %, 7.6 % and 9.7 % in the open-field system, respectively. The EFs of the greenhouse production system increased with increasing soil organic matter. Boosted regression tree analysis showed that N application rate, pH and soil organic matter were the main driving factors of EFs in the greenhouse system. Vegetable type, pH and soil organic matter were the main driving factors in the open-field system. In this study, the EFs were evaluated and distinguished across greenhouse and open-field systems, and the results provided accurate EFs under different management practices and soil properties for vegetable production in both greenhouse and open-field systems.

First report of black root rot (Berkeleyomyces rouxiae) on greenhouse hemp (Cannabis sativa) in Kentucky.

Hemp, Cannabis sativa, was reintroduced to the US in 2014 after 50 years of prohibition. Since then, growers have focused primarily on cannabinoid production using female plants. Thus, most modern hemp has been asexually propagated in greenhouses and transplanted into fields. In December 2019, a commercial transplant producer in Fayette County, Kentucky reported 30% dieback on 'Seagull' hemp. Plants were potted into artificial media (unknown origin) immediately upon removal from the mist bench, and symptoms developed approximately two weeks afterward. Scattered plants developed stunting, yellowing, and wilting symptoms and then died within one week of symptom development. Roots had brown to black lesions distributed along roots that progressed into necrosis. Aleuriospores (chlamydospores) were visible under the dissecting microscope. Root pieces were surface sterilized with 10% household bleach for 2 min and then plated onto cut centers of ~1 cm thick sterilized carrot cross section (Williamson 2014). Resulting colonies were single-spored and maintained on PDA plates on laboratory benchtops (23°C, fluorescent lights). Three isolates were selected for pathogenicity testing and identification. Resulting colonies initially appeared white but darkened to black within two days following the development of aleuriospores (chlamydospores). Aleuriospores were dark brown, formed in chains of 4 to 5, and measured 10.00 to 14.27 × 5.62 to 11.23 μm (n=50). Endoconidia were hyaline, cylindrical, and measured 11.63 to 34.10 × 3.95 to 5.58 μm (n=50). To confirm pathogenicity, soil was washed from three 4-week-old hemp plants (proprietary cultivar) and roots were soaked in a 1x106 spore/mL conidial suspension for 5 minutes. In addition, the roots of three control plants were mock inoculated using sterile water. Inoculated and control plants were transplanted into sterile potting media and maintained in separate trays. Inoculated plants developed leaf yellowing and wilting symptoms 14 dai. Roots examined 21 dai had scattered brown lesions throughout and were colonized by the fungus. Aleuriospores and endoconidia isolated from the symptomatic roots were identical to the inoculum. Control plants did not develop symptoms after 21 dai. For molecular analyses, DNA was extracted from an actively growing (5 d) representative isolate (19FY005) on PDA using Quick-DNA™ Fungal/Bacterial Miniprep Kit (Zymo Research, Irvine, CA). Fragments of commonly used diagnostic loci ITS, ACT, RPBII and Mcm7 were amplified as described by de Beer et al (2014), Fourie et al (2015) and Duong et al (2012). Amplicons were sequenced by Sanger sequencing and the consensus sequences were compared with the NCBI GenBank database by BLASTn. ACT amplicon (OK135163) top hit was B. rouxiae (MF967149.1) with 100% similarity, Mcm7 (OK135165) top hit was B. rouxiae (MF967103.1) with 100% similarity, RPBII (OK135166) top hit was B. rouxiae (MF967194.1) with 99.80% similarity, and ITS (OK135164) top hit was B. rouxiae (MF952402.1) with 99.82% similarity. Berkeleyomyces spp (syn Thielaviopsis sp.) is the causal agent of black root rot in field crops such as cotton and tobacco and in ornamentals such as holly and pansy; it is also a common disease in greenhouse production systems. Introduction of a cryptic sister species in 2017 may suggest that reports of black root rot in many crops may be either B. basicola or B. rouxiae, both species are indistinguishable by morphology (Nel et al. 2017). Although both species have wide host ranges with no host specificity, speciation may be important in terms of pathogenicity, host susceptibility, and other cultural factors. As hemp acreage increases across the US, black root rot may become a more prominent disease in greenhouse transplant production systems and in fields.

Influence of Arbuscular Mycorrhizal Fungi on Physiology and Yield of Eggplant in Organic Soilless Production System

Recent studies suggest that arbuscular mycorrhizal fungi (AMF) have the potential to improve the growth and yield of eggplant (Solanum melongena L.) under soil-based organic production systems. However, the application of AMF in organic soilless vegetable production in a greenhouse has not been well studied, creating an important knowledge gap. Therefore, two greenhouse experiments [Experiment 1 (E1) and Experiment 2 (E2)] were conducted to investigate the effect of AMF (Glomus spp.) on the growth, gaseous exchange, and yield of eggplant fertilized with various liquid organic fertilizers (OFs) and inorganic fertilizers (IFs) in a soilless greenhouse production system. The experiment was conducted in a split-plot design with four replications in which liquid OFs [OF1 (5N–1P–1K), OF2 (0N–5P–5K and 3N–3P–3K), OF3 (3N–1P–1K), OF4 (5N–1P–2K), OF5 (3.7N–2.7P–3.7K), and OF6 (3N–3P–5K)], and IFs [IF1 (6N–4P–4K) and IF2 (4N–0P–1K and 1N–3P–5K)] were randomized as main plot factor, and AMF [inoculated and uninoculated (control)] as a subplot factor. Results indicate that AMF inoculation had no significant effect on the growth, gaseous exchange, and yield parameters of eggplant. Among different OFs, the eggplant fertilized with OF6 resulted in a 4.3% and 3% reduction of leaf area compared with top-performing IF1 treatment in E1 and E2, respectively. Further, the OF6 treatment resulted in a 12% and 15% reduction in total yield per plant compared with IF1 in E1 and E2, respectively. The differences in plant gaseous exchange parameters were also nonsignificant for eggplants fertilized with different OF and IF treatments in both E1 and E2. These results conclude that Glomus spp. were not associated with a significant increase in the yield of eggplant in the soilless production system. However, OFs were performing similar to IFs in terms of growth and yield, which could be due to a higher nutrient availability of these OFs, which are highly useful for the production of eggplant in greenhouse soilless production systems.

Profile of Bacterial Community and Antibiotic Resistance Genes in Typical Vegetable Greenhouse Soil.

The use of vegetable greenhouse production systems has increased rapidly because of the increasing demand for food materials. The vegetable greenhouse production industry is confronted with serious environmental problems, due to their high agrochemical inputs and intensive utilization. Besides this, antibiotic-resistant bacteria, carrying antibiotic-resistance genes (ARGs), may enter into a vegetable greenhouse with the application of animal manure. Bacterial communities and ARGs were investigated in two typical vegetable-greenhouse-using counties with long histories of vegetable cultivation. The results showed that Proteobacteria, Firmicutes, Acidobacteria, Chloroflexi, and Gemmatimonadetes were the dominant phyla, while aadA, tetL, sul1, and sul2 were the most common ARGs in greenhouse vegetable soil. Heatmap and principal coordinate analysis (PCoA) demonstrated that the differences between two counties were more significant than those among soils with different cultivation histories in the same county, suggesting that more effects on bacterial communities and ARGs were caused by soil type and manure type than by the accumulation of cultivation years. The positive correlation between the abundance of the intI gene with specific ARGs highlights the horizontal transfer potential of these ARGs. A total of 11 phyla were identified as the potential hosts of specific ARGs. Based on redundancy analysis (RDA), Ni and pH were the most potent factors determining the bacterial communities, and Cr was the top factor affecting the relative abundance of the ARGs. These results might be helpful in drawing more attention to the risk of manure recycling in the vegetable greenhouse, and further developing a strategy for practical manure application and sustainable production of vegetable greenhouses.

The Case for Sanitation as an Insect Pest Management Strategy in Greenhouse Production Systems

Abstract Protection of greenhouse-grown horticultural crops, including ornamentals and vegetables, from damage caused by insect pests involves implementing strategies such as insecticidal and/or biological control. However, cultural control may also mitigate plant damage caused by insect pests, as well as plant diseases including fungi and bacteria. An important cultural control is sanitation. Herein, we review the use and potential impact of sanitation practices as a part of an integrated pest management program for greenhouse production. These include removing weeds from inside and around the greenhouse perimeter, disposing of plant and growing medium debris from inside the greenhouse, and managing algae within the greenhouse. Weeds serve as alternate hosts for insects, such as aphids (Aphididae), whiteflies (Aleyrodidae), and thrips (Thripidae), that can spread plant viruses among greenhouse-grown horticultural crops. Sanitation practices that may reduce problems with weeds include installing geotextile fabric barriers underneath benches and on walkways, hand removal, mowing around greenhouse perimeters, and/or applying herbicides. Plant and growing medium debris serve as sources of insect pests, such as whiteflies, thrips, and fungus gnats (Sciaridae). Therefore, removal of plant and growing medium debris from within greenhouses and/or placement into refuse containers with tight-sealing lids before disposal may reduce problems with insect pests. Algae provides a habitat for fungus gnats and shore flies (Ephydridae) to breed. Overwatering and overfertilizing plants contributes to algae growth. Applying disinfectants or algaecides may mitigate problems with algae accumulating in greenhouses. In addition to reducing insect pest problems, sanitation practices may help reduce inputs from insecticide applications.

Greenhouse Robots: Ultimate Solutions to Improve Automation in Protected Cropping Systems—A Review

In recent years, agricultural robotics has received great attention in research studies, being considered a way to address some important issues of the agricultural sector, such as precision agriculture, resources saving, improvement of safety conditions, and shortage of human labor. These issues are particularly relevant in greenhouse production systems, where many highly repetitive and sometimes dangerous operations are still required to be performed by humans. The purpose of the present review is providing an overview of the research conducted in recent years related to robotic automation for greenhouse applications. The currently available literature about robots and automated solutions for greenhouse applications has been reviewed through the consultation of international databases of journals. A total of 38 publications were included after screening and the information related to each retrieved automated solution was classified. The research highlighted great variability among studies, which often describe automation solutions designed for specific crops and define the specific “supporting tasks” necessary for the completion of a “main task”. Specifically, the technologies used for guidance and navigation systems, crop detection and fruit grasping system, spraying system, and other minor supporting tasks have been described. Furthermore, a critical appraisal of the main challenges of the sector and future research directions are provided.