Research Project: Development of Technologies and Strategies for Sustainable Crop Production in Containerized and Protected Horticulture Systems

Location: Application Technology Research

2019 Annual Report

Objectives
The overall objective of this project is to conduct research that is relevant to the containerized nursery and greenhouse production (protected horticulture) industry, which will produce outcomes that enhance efficiency, improve economic return, and reduce environmental impact. The following objectives, which have been identified during the past project cycle; have been carefully selected by the Greenhouse Production Research Group to meet priority researchable needs of the industry. Staff and resources have been assembled to address these researchable objectives, and initial research has yielded a base of knowledge, appropriate research skills, and procedures to address this project. Over the five-year planned duration of this project, it is anticipated that there will be significant enhancement of floricultural and nursery productivity with optimization of water, nutrient, fertilizer, and crop protection inputs while minimizing agrochemical, labor, and environmental impacts. Objective 1: Determine the role of silicon in management of abiotic stresses in protected horticulture production systems. Sub-objective 1.1: Elucidate the mode of action of supplemental silicon on the alleviation of abiotic stress symptoms. Subobjective 1.2: Identify a strategy for supplying supplemental silicon in protected horticulture systems. Objective 2: Determine the influence of environmental parameters on growth and development of protected horticulture crops and incorporate the information into user friendly decision support software such as Virtual Grower. Sub-objective 2.1: Quantify photosynthetic responses of protected horticulture crops to environmental parameters. Sub-objective 2.2: Evaluate energy-efficient lighting and heating strategies for bedding plant production. Sub-objective 2.3: Expand the decision support model Virtual Grower to include additional production parameters and crops. Objective 3: Develop management strategies for containerized crop production systems that improve crop growth, reduce costs, and reduce loss of nutrients and agrichemicals to the environment. Sub-objective 3.1: Quantify the chemical and physical properties of novel materials that provide producers with substrates that are economical, sustainable, and effective. Sub-objective 3.2: Determine the utility of biochar for supplying phosphate and potassium in peat and bark-based substrates. Sub-objective 3.3: Through improved understanding of weed biology,develop methods for weed control in crops and sites where herbicides are not labeled. Objective 4: Develop improved techniques for monitoring invasive ambrosia beetles in nurseries based on new knowledge of behavior, movement, and flight activity across different habitats. Objective 5: Characterize the role of tree health on the host-selection and host preference behavior of ambrosia beetles in ornamental nurseries. Objective 6: Develop improved technology for applying or improving the efficacy of chemicals to effectively manage ambrosia beetles and evaluate alternatives to conventional insecticides for managing ambrosia beetles in nurseries.

Approach
A multi-disciplinary team will address the goal of enhancing containerized crop production in the context of protected horticulture by utilizing a three-fold approach to address production efficiency, economic return, and environmental impact. Plant nutrition, including the role of silicon as mediated through soilless media composition, will be studied to determine how plant stress is impacted by nutrient supply in both floricultural and nursery crops. Environmental parameters, such as light, temperature, and carbon dioxide, will be evaluated for their influence on growth and development and results will be incorporated into our decision support software model, Virtual Grower. Management strategies will include chemical and physical quantification of substrate components, as well as determination of the utility of novel components as sources of macronutrients in nutrient deficient soilless media, and the improved understanding of weed biology to improve control approaches for crops and sites which lack current herbicide alternatives.

Progress Report
Research was initiated on a new technique for preventing phosphate leaching from nursery containers. Pine bark, the primary substrate component used for containerized crop production in eastern U.S. nurseries, retains phosphorus (P) poorly. Consequently, P fertilizer readily leaches from containers during irrigation and can subsequently runoff to adjacent surface waters with negative environmental effects. Our objective was to determine the effect of a base-layer (2.5 cm deep) of pine bark amended with other components on P amounts leached when fertigating 2.6-L fallow nursery containers filled with otherwise non-amended pine bark. This research furthers Objective 3, which aims to develop management strategies for containerized crop production systems that improve crop growth, reduce costs, and reduce loss of nutrients and agrichemicals to the environment. Containers were fertigated daily with ˜109 mL of a solution containing 100, 5, and 50 mg·L-1 of N, P, and K, respectively. The cumulative P load and average P concentration in leachate after 21 d was 93% lower from containers with the modified substrates compared to the control. These results suggest that a layer of modified substrate could dramatically reduce P leaching and subsequent runoff from containerized nurseries. However, additional research is needed to determine the optimal incorporation rate of the components, potential effects on plant health, and the longevity of these P-retaining effects. The microbial community is poorly understood in container substrates. Research continued to document the influence of common container nursery practices on diversity of the microbial community in pine bark substrates, and to document changes over time. This research furthers Objective 3, which aims to develop management strategies for containerized crop production systems that improve crop growth, reduce costs, and reduce loss of nutrients and agrichemicals to the environment. The objective of work this year was to investigate the effect of composts on microbial communities within peat-based substrates used for greenhouse production. Microbial communities changed over time, regardless of the initial treatment conditions. Furthermore, microbial communities tended to become similar across substrate treatments, suggesting the environmental conditions have more influence on microbial communities than initial substrate components or amendments. Weed control in container nursery production continues to be a major expense and use of labor. Research was conducted to determine how pre-emergence herbicides dissipate over time as a function of shade and light levels. This research furthered Objective 3, which aims to develop management strategies for containerized crop production systems that improve crop growth, reduce costs, and reduce loss of nutrients and agrichemicals to the environment. Of the four herbicides evaluated, all dissipated differently in response to shade level. Future research will evaluate herbicide longevity as a function of irrigation frequency, fertilization, and substrate type. Silicon (Si) can help mitigate the effects of abiotic and biotic stress. As part of Objective 1, which seeks to determine the role of silicon in management of abiotic stresses in protected horticulture production systems, the utility of supplying supplemental Si as a substrate amendment was evaluated during drought and cold stress. Supplemental Si improved growth compared to a non Si-amended control. Silicon was also shown to alleviate copper toxicity in Nicotiana tabacum by reducing root Cu concentration, downregulating the expression of COPT1 (which encodes a high-affinity copper transporter), and increasing the expression of ethylene biosynthetic genes; this suggests a regulatory function of Si in plants. Optimized environmental conditions in greenhouses and other controlled environments are important for enhancing yield while minimizing resource use and cost but are often crop or cultivar specific. As part of Objective 2, single-factor photosynthesis curves were developed for four herbs (basil, oregano, parsley, and sage) and eight tomato cultivars in response to light intensity and carbon dioxide concentration. Research has discovered the combination of elevated temperature (37 °C) and elevated carbon dioxide concentration (700 ppm) drastically hinders growth of tomato in controlled environments. This results from the occurrence of leaf hyponasty (upward bending of leaf), which reduces light interception and leads to reduced photosynthesis and biomass accumulation. This phenomenon has preliminarily been shown to vary in severity in different tomato cultivars. It appears to occur in compound-leaved plants in Solanaceae. Work is ongoing to further elucidate this response in plants and its impact to crop productivity. In collaboration with researchers from Virginia Tech, ARS scientists in Wooster, Ohio, tested a range of ethanol release rates from lures to determine the optimal release rate for mass trapping ambrosia beetles as part of push-pull management strategy. Field experiments were conducted in Ohio and Virginia. Specimens are currently being sorted and identified to determine variability among different species of ambrosia beetles for the preference for ethanol emissions. Seasonal activity of ambrosia beetles were monitored, particularly for a new species of ambrosia beetle that has been introduced to Ohio and neighboring states and begun attacking nursery trees. Weekly trapping data will be used to characterize peak flight for established and recently established species to assist with properly timing insecticide applications. In collaboration with researchers from the Slovak Academy of Sciences, electroantennogram responses of an exotic ambrosia beetle were compared to absolute vs. denatured ethanol. No difference was detected in antennal sensitivity. Denatured ethanol was determined to be an inexpensive and effective alternative to absolute ethanol. In collaboration with researchers from University of Kentucky, we compared vinegar based hardwood extracts vs. ethanol and a blank control. Ethanol was more attractive, but the vinegar hardwood extracts attracted more beetles than the blank control. We will attempt to identify compounds in the hardwood extracts that influence ambrosia beetle behavior for developing an improved lure. In collaboration with researchers from University of Padova, we assessed the attraction of ambrosia beetles to logs soaked with different concentrations of ethanol. Ambrosia beetles were found to have different preferences for the host material based on the emissions of ethanol. In collaboration with the University of Georgia, we tested the efficacy of insect growth regulators for disrupting the proper development of ambrosia beetles. The products were not found to be as effective as a standard permethrin treatment. In collaboration with Tennessee State University, we tested the residual duration of an insecticide and fungicide treatment for ambrosia beetles. Trees were treated in the field and bolt sections of stems are currently being analyzed for time course residue of insecticide and fungicide treatment. Insecticide impregnated fabric was tested for protecting the stems of flood-stressed trees from attack by ambrosia beetles. Research on the relationship between duration of stress on trees and ambrosia beetle colonization was initiated in FY18 and continued in FY19. In collaboration with researchers at Virginia Tech the influence of flood duration on colonization success of ambrosia beetles was tested on ‘Golden Delicious’ apple trees, flowering dogwoods, and eastern redbuds. So far, the data indicates colonization success increases as flood duration increases, and trees flooded for short time-periods can tolerate attacks. Ambrosia beetles attack then tend to abandon trees flooded for short time-periods, and the attack entrances heal over. In 2018, dogwood trees flooded for only 3 days were attacked and showed no adverse effects, then survived winter, bloomed in spring 2019, and appear healthy. Research on monitoring and seasonal activity of flea beetles in nursery crops was initiated in FY19. Commercially available sticky cards (traps) of various colors are being tested for monitoring red-headed flea beetle activity in commercial nurseries. Plants in monitored plots are also visually inspected for beetles and feeding damage to help evaluate trap efficacy. We thought there might be a complex of flea beetles attacking plants, but only red-headed flea beetles have been found at this time. Beetles have been found in nurseries in Erie and Lake Counties Ohio. Red-headed flea beetles emerged later than expected this year (a month later based on previous reports), being first detected 2 July in Erie and 8 July in Lake County. Beetles were detected by visual inspection and on sticky cards on the same date. Visually inspecting plants has been as effective and easier to do than using sticky cards. Research was conducted with university collaborators to evaluate biological control agents for fungus gnats attacking gourmet mushrooms grown within controlled environments. Promising control tactics were identified and will be further evaluated. Research was conducted to evaluate entomopathogenic fungi for controlling aphid pests of horticultural crops grown within controlled environments. Previously unknown interaction has been characterized and is being pursued to improve the efficacy of the entomopathogenic fungi.

Accomplishments
1. Integrating attractants and repellents for ambrosia beetle management. Multi-state and multi-year experiments were conducted to evaluate the integration of repellent and attractant semiochemicals for reducing ambrosia beetle pressure on horticultural trees. The repellent compound verbenone did not effectively protect trees or enhance the attractiveness of ethanol. However, ethanol-baited interception traps were effective under light population pressure for reducing attacks on trees.

2. Elevated temperature and carbon dioxide can induce leaf orientation changes in plants and limit growth. Elevated temperature and elevated carbon dioxide concentrations, individually, can increase plant growth but in combination they may have adverse impacts on crop growth and productivity. Researchers at the University of Toledo, Toledo, Ohio, in collaboration with ARS researchers, in Toledo, Ohio, have discovered the occurrence of leaf hyponasty (upward bending of leaves) in tomato plants grown at elevated temperature and elevated carbon dioxide. It was prevalent across multiple tomato genotypes. It also appears to occur in other plant species with compound, but not single, leaves. Results of this research can guide the development of production protocols for tomatoes and other crops produced in controlled environments aimed at yield optimization.

Review Publications
Boldt, J.K., Altland, J.E. 2019. Timing of a short-term reduction in temperature and irradiance affects growth and development of four annual bedding plants. Horticulturae. 5(1):15. https://doi.org/10.3390/horticulturae5010015.
Galko, J., Dzurenko, M., Ranger, C.M., Kulfan, J., Kula, E., Nikolov, C., Zubrik, M., Zach, P. 2018. Distribution, habitat preference, and management of the invasive ambrosia beetle Xylosandrus germanus (Coleoptera: Curculionidae, Scolytinae) in European forests with emphasis on the West Carpathians. Forests. 10(1):10. https://doi.org/10.3390/f10010010.
Altland, J.E., Jeong, K. 2018. Initial substrate moisture content and storage temperature affect chemical properties of bagged substrates containing poultry litter fertilizer. HortScience. 53(8):1191-1196. https://doi.org/10.21273/hortsci13004-18.
Altland, J.E. 2018. Lime rate affects substrate pH and container-grown birch trees. Communications in Soil Science and Plant Analysis. 50(1):93-101. https://doi.org/10.1080/00103624.2018.1554670.
Newby, A., Altland, J.E., Struve, D., Pasian, C., Ling, P., Jourdan, P., Kessler, R., Carpenter, M. 2018. Integrating moisture characteristic curves with gravimetric data in the management of substrate moisture content for annual vinca. HortScience. 53:1197-1202. https://doi:10.21273/HORTSCI13030-18.
Sun, Y., Niu, G., Perez, C., Pemberton, H., Altland, J.E. 2018. Responses of marigold cultivars to saline water irrigation. HortTechnology. 28(2):166-171. https://doi.org/10.21273/HORTTECH03981-18.
Basiri, N., Walker, F., Fulcher, A., Altland, J.E., Wright, W. 2018. Growth response, mineral nutrition, and water utilization of container grown woody ornamentals grown in biochar-amended pine bark. HortScience. 53(3):347-353. https://doi.org/10.21273/HORTSCI12643-17.
Ranger, C.M., Schultz, P.B., Frank, S., Reding, M.E. 2018. Freeze stress of deciduous trees induces attacks by opportunistic ambrosia beetles. Agricultural and Forest Entomology. 21(2):168-179. https://doi.org/10.1111/afe.12317.
Altland, J.E., Owen, J., Jackson, B., Fields, J. 2018. Physical and hydraulic properties of commercial pine-bark substrate products used in production of containerized crops. HortScience. 53(12):1883-1890. https://doi.org/10.21273/HORTSCI13497-18.
Addesso, K., Oliver, J., Youssef, N., O'Neal, P., Ranger, C.M., Reding, M.E., Werle, C.T. 2019. Trap tree and interception trap techniques for management of ambrosia beetles (Coleoptera: Curculionidae) in nursery production. Journal of Economic Entomology. 112(2):753-762. https://doi.org/10.1093/jee/toy413.
Craver, J.K., Boldt, J.K., Lopez, R.G. 2018. Radiation intensity and quality from sole-source light-emitting diodes affect seedling quality and subsequent flowering of long-day bedding plant species. HortScience. 53:1407-1415. https://doi.org/10.21273/HORTSCI13228-18.
Craver, J.K., Boldt, J.K., Lopez, R.G. 2019. Comparison of supplemental lighting provided by high-pressure sodium lamps or light-emitting diodes for the propagation and finishing of bedding plants in a commercial greenhouse. HortScience. 54:52-59. https://doi.org/10.21273/HORTSCI13471-18.
Jayawardena, D.M., Heckathorn, S.A., Bista, D.R., Boldt, J.K. 2018. Elevated carbon dioxide plus chronic warming causes dramatic increases in leaf angle in tomato, which correlates with reduced plant growth. Plant Cell and Environment. 42(4):1247-1256. https://doi.org/10.1111/pce.13489.
Flora, C.S., Khandekar, S., Boldt, J.K., Leisner, S. 2019. Silicon alleviates long-term copper toxicity and influences gene expression in Nicotiana tabacum. Journal of Plant Nutrition. 42(8):864-878. https://doi.org/10.1080/01904167.2019.1589508.