Author Archives: Rita Weerdenburg

Water recycling is increasingly recognized as necessary to deal with the dual issues of water availability and the ever-evolving environmental restrictions faced by greenhouse and nursery producers related to water run-off. Although conservation has become an essential objective, the practice of using recycled water poses many risks and challenges. Recirculated water often contains nutrient, pesticide and plant growth regulator (PGRs) residues which could negatively affect crop production. Research is being conducted around the world to improve recycled water quality, and several projects currently being funded through the COHA research cluster are especially focused on sustainable and affordable solutions.

Enabling re-circulation with hybrid treatment systems is the next phase of longer-term water research being led by environmental microbiologist Dr. Ann Huber of the Soil Resource Group. This project is part of the Cluster Project and is funded by the Canadian Ornamental Horticulture Alliance (COHA-ACHO) and by the Government of Canada under the Canadian Agricultural Partnership’s AgriScience Program.

Simply stated, a hybrid treatment system (HTS) is a non-vegetated, constructed approach to the filtration and cleansing of water through a series of organic and inorganic media filters. Explains Dr. Huber, “An HTS is the next step in water cleaning technologies as a successor to previous research into constructed wetlands and woodchip bioreactors. While those individual approaches have been found to be useful for some pathogen and nutrient removal, there are many external factors that can impact their usefulness.”

Earlier projects by Dr. Huber have already proven the effectiveness of hybrid treatment systems in the removal of certain nutrients, including nitrogen and phosphorus, and fungal pathogens. The objective of the current project is to expand those research findings to include other greenhouse production chemicals and especially plant growth regulator (PGR) residues, which have been shown to impact plant growth even when found in very low levels of recirculated water.

Due to their typical four- to five-year funding cycle, research projects are generally defined by very specific start and end dates. However, as water issues within the horticulture sector have long been a top priority for both governments and industry, Dr. Huber has succeeded in making her research into effective water re-circulation technologies a mostly continuous long-term field of study, beginning in 2007.

Besides the very obvious benefits of providing the industry with continually updated research results, the continuity of Dr. Huber’s research projects also provides significant economic efficiencies. Two portable pilot units constructed as part of a previous research project funded with support from Flowers Canada Ontario (FCO) at a cost of $50,000 each are now an integral component of this next-phase study.

According to Dr. Huber, “As far as I’m aware, there are no other pilot-scale systems such as these being used for water re-circulation research.  The system is designed to have the capacity to test up to eight mineral or organic media in any combination or alternatively, test the same media at different flow rates and retention times. These pilot systems provide us the opportunity to test commercial greenhouse water on-farm without risking the health of the crop.”

The original focus of Dr. Huber’s work was to study the effectiveness of woodchip denitrification bioreactors on the removal of various water pollutants. Although she continues to be optimistic about the use of woodchip as an effective and economical treatment for some contaminants, the current research project also incorporates a number of mineral media, including pea gravel, wollastonite, filter sand and a slag/gravel mix to expand the range of undesirable components that can be removed within a single ‘hybrid’ treatment system.

And, although other researchers are studying organic systems (e.g. woodchips) which employ an aerobic process to remove pesticide and PGR residues, the research work being conducted by Dr. Huber and her research team is an ongoing study of an anoxic approach in order to retain the current treatment system’s capacity to remove nitrogen and fungal pathogens.

With the current research project reaching the half-way mark during the fall of 2020, Dr. Huber and her team have been able to successfully mitigate the impacts of Covid19 that might have otherwise negatively impacted their progress.  Most of the work has been outdoors and in low-contact environments, and both Dr. Huber and collaborator Dr. Jeanine West were also extremely fortunate to have access to qualified family technicians.

Although the preliminary research results are not conclusive, to date the data collected by the research team, based on water quality analysis and results of bioassay testing indicate very promising results. The team has been able to demonstrate the removal of a range of PGRs and pesticides by several of the individual media in batch studies, and the bioassay results demonstrate a positive growth response to PGR removal. Interestingly, the bioassay tests are capable of detecting the presence of some PGRs at concentrations lower than the sensitivity of laboratory testing.

Because this is a very new technology, only three growers — two floriculture greenhouses and one nursery grower — are currently using hybrid treatment systems to treat recycled irrigation water. The research team is confident that these early results will meet their original objective, to provide growers with a valuable and affordable approach to realize clean recycled water for their production needs.

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Research team:

Dr. Ann Huber, Soil Resource Group

Dr. Jeanine West, Phytoserv

Within the ornamental sector, an ever-evolving environmental movement has resulted in the demand for more ecologically responsible plants and plant production techniques. The demand for low-maintenance, drought resistant, low-input plants has converged with the trend to the use of more natives and pollinator plants in our gardens and landscapes.  However, as any garden centre owner or landscape designer knows all too well, aesthetic attributes on the sale’s bench or in the landscape plan are all-important.  And, from the perspective of greenhouse growers, cost-effective propagation and production technologies are an absolute must if these otherwise desirable plants are to find a way to the consumer’s garden.

Exploring a variety of integrated systems designed to overcome the obstacles that are generally associated with the efficient production of native species, “Integrated techniques for efficient breeding, production and transplant survival of unique ornamental species” is an ambitious research project currently underway at the University of Guelph.  This project is part of the Cluster Project and is funded by the Canadian Ornamental Horticulture Alliance (COHA-ACHO) and by the Government of Canada under the Canadian Agricultural Partnership’s AgriScience Program.

Bringing these diverse and lofty goals to this project is achievable largely through a unique collaboration of expertise and facilities.  Leading the project, Dr. Alan Sullivan has over 25 years of experience in horticultural breeding with the past 10 years focused on breeding and physiology of native ornamental species that are tolerant to low water and low nutrient conditions.

The project’s co-lead, Dr. Praveen Saxena, has spent 25 years working with stakeholders of the floriculture and horticulture sectors to develop efficient protocols for rapid in vitro multiplication of a diverse range of ornamental and medicinal plants.  Dr. Saxena is also the director of the GRIPP Institute, a University of Guelph based organization led by himself and Dr. Sullivan dedicated to the preservation of endangered plant species. GRIPP makes some sophisticated facilities available to this project, including cryopreservation technologies.

With a goal of developing improved varieties and germplasm of existing plant species that already exhibit the required environmental and aesthetic attributes, the project relies on the expertise of Rodger Tschanz, manager of the University’s ornamental trial garden program.  Rodger’s many years of on-the-ground supervision of various trial garden programs and other related horticultural projects makes him uniquely qualified to help identify native plants with superior ornamental qualities that are adapted to environmentally challenging conditions.

Focused on two impressive goals – the accelerated breeding and introduction of exiting new perennial plants to the marketplace, together with the development of efficient propagation and production technologies – both Dr. Sullivan and Dr. Saxena are equally excited about the potential economic impact to all sectors of the ornamental industry.  “It is our goal to make available to the Canadian ornamental industry a whole new selection of commercially available native plants that support a strong marketplace trend,” said Dr. Sullivan.

Although off to a promising start, keeping the project on track during the COVID-19 shutdown has proven to be a challenge for Dr. Sullivan and Dr. Saxena.  “The COVID impacts were severe,” noted Dr. Sullivan.  “We are grateful to the University for their positive response to our various applications to continue our research, even on a limited basis, as we had plants that had come out of cold storage and were coming into flower for crossing if we were to keep the project alive and somewhat on track.”

The project team is now coping with a number of unforeseen expenses.   Additional greenhouse space is required to accommodate social distancing requirements, and extra costs incurred for more vehicles and trips due to COVID restrictions continue to mount.  These unanticipated costs are nonetheless a far better scenario than the alternative of having to start over again.

With some ingenuity and creative solutions, the first objective of the project remains on track.   Employing both traditional and advanced breeding methods, new and improved varieties of pre-selected species will be developed and further trialled in the UofG trial garden network.   The 10 species selected for this program, include Lobelia, Helinium, Physotegia, Allium, Penstemon, Monarda and Aquilegia.  Not included on the original plant list, Dr. Saxena is excited that he has since secured several native and exotic orchid species to add to the collection.

Efficient production will be key to ensuring commercial success of these new varieties.  Drawing on research results and resources made available through GRIPP, a variety of approaches will be utilized, including an expansion of research already underway to study the ability of indolamines compounds to enhance plant growth and survival.  Optimized tissue culture propagation systems will improve mass production efficiency and cryopreservation techniques will help in biobanking of important genotypes of endangered and horticulturally important species.

As Dr. Saxena pointed out, despite its devasting impacts, the pandemic has brought a whole new focus to the importance of our homes and our gardens.  “A look at the impact of COVID on home gardening shows the importance of ornamental horticulture.  New varieties and especially those that meet our demand for ecologically sound plants will be important to drive the sector into the future.”

Organization: University of Guelph

Research team:

Dr. Alan Sullivan, Professor, Plant Agriculture

Dr. Praveen Saxena, Professor, Plant Agriculture, and Director of GRIPP

Rodger Tschanz, Technician, Manager UofG Trial Garden