A new atomiser, specifically for sprout inhibitors during this 'storage period', has been designed.
The atomiser, known as the Synofog, uses a new technique - electro-thermal atomisation. The advantage of this new piece of apparatus is that it does not have an open flame. This ensures its safe use with all kinds of sprout inhibitors. READ MORE
Close to 50 industry representatives took the opportunity to take part in the annual Variety Day at Harrington Farm showcased potential entries for the Accelerated Release program of Agriculture and Agri-Food Canada, variety trials conducted by the PEI Potato Board, as well as a tour of the organic potato acreage.
There was also a chance to view a soil building rotation trial being conducted in conjunction with the Enhanced Agronomy Initiative-- a fund established in 2016 by processing growers. READ MORE
Enviroot's goal is to reduce waste by using food remains, especially potato peelings, to make a safe material for use in the home.
The company received a national business prize of $20,000 from Enactus Canada, a student-led entrepreneurial organization, and the McCain Social Enterprise Project Partnership to get the project going this summer.
"We use the potato peels that we get from McCain Foods here in New Brunswick in our particle board as a kind of filler," said Justin Trueman, Enviroot CEO and fourth-year biology student.
The potato peels are plasticized by melting them a little bit, and a bond between the potato peels' particles is created.
This allows them to bind products together without need of formaldehyde, which is the glues of some household furnishings, walls and stairs made from composite wood materials. READ MORE
First identified in Ontario potatoes in 2015, Dickeya is shaping up to be a problem. Photo courtesy of Tracy Shinners-Carnelley.
Potato growers are familiar with the problems that stem from blackleg and are adept at managing it. However, two new strains have been identified and one has been spreading in North America for the last two years. Dickeya dianthicola has been affecting potatoes in Europe since the 1970s, but is now found frequently in the United States, particularly in Maine and south along the eastern seaboard. Dickeya is most probably spread on seed and is shaping up to be a problem in North America.
“Dickeya may have two problem features,” says Amy Charkowski, a potato specialist at the University of Wisconsin. “It needs fewer cells to cause disease and it can remain in a kind of dormancy until the right conditions trigger the disease.” She adds the bacteria thrives under wet conditions and is an equal opportunity pathogen so can be found on other vegetables and some ornamental plants. Dickeya does not seem to favour grains and legumes, which makes crop rotation a good option to lessen its spread.
Blackleg seems to resemble the common cold because it changes. Growers use management practices to control the disease, but this new species is not so easily harnessed using this familiar method. Crop protection products are not effective on Dickeya dianthicola. Meanwhile, researchers have identified Dickeya solani in Europe that is very aggressive and is not easily controlled, but it has yet to cross the ocean. This proves that complacency, when it comes to blackleg control, is not an option.
“We found Dickeya in Ontario potatoes in 2015,” says Gary Secor, a plant pathologist from North Dakota State University in Fargo. “The seed came from Maine, which is an example of how easily it spreads.”
To minimize the spread of Dickeya, both Charkowski and Secor recommend not cutting seed and, instead, using the whole tuber. Since it does not survive well in soil, they also recommend diligent crop rotation. “There are no food safety issues, but there is still a lot we don’t know about Dickeya,” Secor says. “We also don’t have any idea what the economic thresholds might be.”
“We are applying for grants to allow us to focus more research on Dickeya,” Charkowski says. “We want to learn what breeders need to know to enable them to breed for resistance, and we need to determine what the thresholds are for seed.
The symptoms are similar to the strains of blackleg growers are familiar with, so tubers need to be tested to identify Dickeya. “If it is present the most noticeable symptom is plant wilting,” Charkowski explains. “There will be rotten potatoes at harvest and there could be rotting at plant emergence.” She says determining an accurate laboratory test may be part of the planned research, but a field assay would be more helpful. Knowing the strain may help determine the most effective control as well.
“A lot of co-operation is required with all agencies working together to make progress on identification and control,” Secor admits. “Certification agencies need to determine if it requires certification at the seed stage.”
According to Tracy Shinners-Carnelley of Peak of the Market in Winnipeg, the Canadian Food Inspection Agency’s seed potato inspection program has strict tolerance for blackleg infection. “This is likely a factor in how the incidence of blackleg in Canada is quite low,” she says. In the United States, she adds, blackleg is not part of the industry’s seed certification process, which puts Canadian growers at a bit of an advantage when seed changes hands because it is screened. However, accurate tests for particular strains of Dickeya may be necessary if the more virulent versions enter North America.
“Canadian growers need to be aware of the risks and be proactive in order to prevent the introduction or establishment of any new disease,” Shinners-Carnelley continues. “My main message to growers is to follow best management practices and this, combined with the use of certified seed, will help to reduce the risk and spread of Dickeya.”
Bernie Zebarth is leading a four-year project that will study large-scale compost application on potato fields in New Brunswick, and the resulting effects on yield and soil health. Photo courtesy of Bernie Zebarth.
In 2013, eastern Canadian potato growers were concerned: they were not seeing the yield increases experienced by growers throughout the rest of North America. Manitoba has seen an average yield increase of 4.4 hundredweight per acre (cwt/acre) each year. By contrast, New Brunswick sits at an average yield increase of 1.4 cwt/acre, and P.E.I. at 1.1 cwt/acre.
One possible culprit for stagnating yields is declining soil health in the eastern provinces. “With sloping land and intensive tillage, you have a lot of issues with soil erosion,” says Bernie Zebarth, a researcher with Agriculture and Agri-Food Canada (AAFC) based in Fredericton. “We also have a short rotation for potato, so we’re not getting much organic matter back to the soil. Our concern is that the declining soil health is limiting yield.”
New Brunswick’s processing potato industry is crucial; the province exports most of its product for french fries, and without increasing productivity it loses competitive advantage.
Industry asked for help, and in 2014, Zebarth took the science lead on a four-year industry-led project that will study large-scale application of compost on fields across New Brunswick, and the resulting effects on potato yield and soil health. Potatoes New Brunswick is leading the project, with McCain Foods Canada heading up the on-farm trials. The project will also study a variety of compost products in experimental plots at the AAFC Fredericton Research and Development Centre.
“We want to see the implications of adding compost to the soil, in terms of yield and tuber quality,” Zebarth says. “How much of a yield difference is there? Will it be cost-effective? How will it fit into growers’ practices? What soil quality parameters does it improve? We want to be able to know which index is the best to use to assess soil health. Can we suppress soil-borne diseases? Will compost fit into New Brunswick potato production?”
The study is part of a larger three-year study that aims to identify areas in New Brunswick, Manitoba and P.E.I. potato fields that have a yield limitation, identify the source of the limitation, and identify mitigation practices to overcome that limitation.
Zebarth says his team is hoping to assess whether adding compost to the soil will help accomplish in a short time what improved rotations might accomplish over a much longer period.
“Because we don’t irrigate, I’m thinking that when it comes to soil health and soil quality, what we’re really after is improvement of the soil’s physical properties, such as water holding capacity and tilth. Any field with a problem with physical properties could benefit from compost.”
The field-scale trials led by McCain in commercial fields for the project involve paired treatment strips in growers’ fields – one treated with compost, one untreated. They are evaluating yield and tuber quality, as well as soil water content and other physical properties of the soil.
Meanwhile, with help from Dalhousie masters student Carolyn Wilson, Zebarth is analyzing five different compost products, assessing their impact on tuber yield and quality, soil quality and on soil-borne diseases like common scab.
The compost being used in the field trials is a wood shaving litter with poultry droppings, which reuses wastes from agriculture and forestry to build soil organic matter. The other composts being analyzed at the Fredericton Research and Development Centre include a forestry residue compost, a source-separated organics compost, a poultry manure-bark compost and a marine-based compost.
The third component of the study is based in the lab, where, along with AAFC researcher Claudia Goyer, Zebarth is using next-generation sequencing to characterize the microbial life in soil samples.
It’s too soon to talk about results. Zebarth is optimistic that compost can help improve soils over time, but he cautions that compost is a “probabilistic” solution. “We’re thinking about compost almost like you look at a capital investment,” he says. “It’s not like a nutrient application, but an infrastructure improvement, where you get payback over the next five to 10 years.”
In some fields, growers may only need to apply compost to certain parts of the field that have soil physical problems. As cost has traditionally been a prohibiting factor for growers hoping to use compost, Zebarth’s team is hoping the study might help them identify a particular compost product that can be scaled up to reduce the costs.
There’s no silver bullet when it comes to soil health, but compost is what Zebarth calls “one tool in the tool box” for improving the soil – and ramping up productivity – over time.
April 29, 2016, Ontario – The Ontario Potato Board and Dr. Eugenia Banks are collaborating on a two-year project to evaluate late blight management technologies new to Ontario.
The goal of the project is to help growers take late blight management to the next level by using state-of-the-art spore traps placed in potato fields and Polymerase Chain Reaction (PCR) technology to identify late blight spores before visual symptoms develop in plants. Also, drone technology will be used to validate the performance and effectiveness of spore traps.
Ontario potato production can be seriously affected by late blight, a devastating disease that can destroy potato fields in a few days if effective fungicides are not applied in a timely fashion. In the past, late blight was sporadic in Canada, but it is now an annual, serious concern for potato and tomato growers in Ontario and other provinces as well.
The late blight pathogen, Phytophthora infestans, has the ability to produce about 700,000 spores on a single leaf lesion. The spores are disseminated by the wind both within a field and also from farm to farm. Each spore has the potential of initiating infections on potato plants or other hosts such as tomatoes and nightshade weeds. This extremely high spore production is the most important factor involved in the destructive nature of late blight.
The innovative technologies for spore trapping in potato fields and for spore identification should allow potato producers to manage late blight more effectively and avoid epidemics that could pose a serious threat to provincial potato production.
Information obtained during the growing season will be shared not only with provincial potato growers but with provincial tomato growers as well.
This project is funded in part through Growing Forward 2. The Agricultural Adaptation Council assists in the delivery of Growing Forward 2 in Ontario.
April 28, 2016, Charlottetown – Christine Noronha, an entomologist with Agriculture and Agri-Food Canada’s Charlottetown Research and Development Centre, has designed an environmentally green trap that could be a major breakthrough in the control of wireworms, an increasingly destructive agricultural pest on Prince Edward Island and across Canada.
In this exslusive webinar hosted by Potatoes in Canada magazine, Christine will share details about the Noronha Elaterid Light Trap (NELT). Don't miss the opportunity to ask questions and learn more from Christine Noronha.
Date: May 12, 2016
Time: 2 p.m. ADT (1 p.m. EDT)
New hope is on the horizon for potato growers engaged in the ongoing battle against Colorado potato beetle (CPB). Researchers are currently field-testing one of the most effective controls ever developed for the potato’s chief insect villain, and it is entirely chemical-free.
RNA interference (RNAi) is a biological process whereby RNA (ribonucleic acid) molecules activate a protective response against parasite nucleotide sequences by inhibiting their gene expression. In other words, it is the method by which organisms – including pests such as CPB – defend themselves against threats and regulate their own genes. But the same process that is used by a beetle to protect itself can be used to destroy it when it consumes the long double-stranded RNA (dsRNA) in genetically modified plants.
Since 2009, researchers at the Max Planck Institute in Potsdam and Jena, Germany, have been developing genetically modified potato plants to enable their chloroplasts to accumulate dsRNA targeted against essential CPB genes. After feeding on a potato’s leaves – and ingesting the dsRNA – the beetles in the study showed 100 per cent mortality within five days.
Why chloroplasts, rather than plant cell nuclei? In past breeding projects, expression of dsRNA in potato plants’ nuclei has proven inefficient because natural RNAi pathways in nuclei prevented the plant from producing enough long dsRNA. But long dsRNA are free to accumulate in chloroplasts – which have no RNAi mechanism – and the plants are fully protected against CPB.
According to Jiang Zhang, a professor with the College of Life Science at Hubei University in China, and the lead on the project, the technology shows great promise for the future of pest management, but there are no immediate plans for commercialization until all regulatory hurdles have been overcome.
“We encourage more scientists and industry involvement in this field for a better future,” Zhang says. “There is still a long way to go to make it really useful in daily life and be accepted by customers.”
RNAi for control of CPB has also gained significant momentum in private research and development. Monsanto and Syngenta have both devoted major investments toward the technology.
In early 2015, Monsanto’s BioDirect technology platform targeted at CPB advanced to Phase 2 – early product development – of the company’s research and development pipeline. The product will have to complete advanced product development and pre-launch before broad commercialization early in the next decade.
While the principle is the same, Monsanto’s product works differently than Max Planck’s modified potato plant: it is sprayed onto the plant’s foliage. Rather than expressing dsRNA in its leaves, dsRNA is applied exogenously to the plant.
“The Colorado potato beetle consumes the leaves of the potato plant where we can focus the BioDirect application, versus needing a plant to produce the dsRNA targeting the pest below-ground where sprays cannot reach,” explains Greg Heck, weed control team lead for Monsanto’s chemistry technology area.
Heck says there are thousands of dsRNA naturally present in host plants that serve a variety of functions, and beetles consume and incorporate dsRNA all the time. “When targeting them for pest control, we seek to supply one additional dsRNA that will turn down a specific gene critical to their ability to feed and grow on the plant.
“Field research conducted on our BioDirect treatment for Colorado potato beetles has already demonstrated some early positive results. This includes reduced Colorado potato beetle larva infestation and plant defoliation in multiple geographies.”
Syngenta’s most advanced RNA-based biocontrol targets CPB in potato – and is also applied via a spray. The company has tested the product in multiple geographies over several years with positive results, says Luc Maertens, Syngenta’s RNAi platform lead based in Belgium. The company hopes to commercialize the product early in the next decade pending continued development and regulatory reviews.
Maertens says the company’s biocontrol is highly selective and starts to work before CPB can cause too much damage.
“The biocontrol is not systemic [in the plant], nor does it work through contact,” he says. “It does not change or have any effect on the DNA of the pest, nor does it involve genetic modification of the plant.”
No technology can work forever, however. Insect resistance to RNAi is a potential risk – one companies and researchers alike are keen to avoid so the technology has maximum benefit and longevity.
Maertens says that as resistance emerges to existing technologies, and the pest spectrum shifts along with climate change and other factors, growers’ needs will change. “Those challenges cannot be answered by only one technology,” he says. “It is imperative to gain insights into probable resistance mechanisms to RNAi triggers in insects, to monitor possible resistance in the field, and to support the use of the technology with appropriate stewardship requirements.”
Of the two methods of RNAi application (genetic modification and spray-on), Zhang believes the former might be better for growers. “Applying dsRNA exogenously is much less cost-effective than expressing dsRNA in the plant itself,” he says. “Spraying may also cause other potential problems in the environment.”
RNAi is not meant to be a silver bullet and should be used as part of a multifaceted pest control strategy. Regardless of the method of application, RNAi may soon be working in a field near you.
Although many consumers aren’t aware of it, potatoes have a lot of good things going for them when it comes to human nutrition. For instance, potatoes contain vitamin C, minerals, fibre, protein and bioactive compounds, plus they help provide a feeling of fullness that discourages overeating. Now an Ontario project is identifying some especially healthy potato cultivars that could help win back health-conscious consumers.
The perception that potatoes are not a healthy food choice has resulted in decreased potato consumption and production in Canada, notes Reena Pinhero, a researcher in the department of food science at the University of Guelph. She is leading this project along with Rickey Yada, dean of the faculty of land and food systems at the University of British Columbia.
Pinhero explains the potato’s bad reputation is based on two factors and she puts those two factors in perspective: “Potatoes are generally considered as a carbohydrate-rich food contributing to high calorie intake and causing weight gain. The fact is a potato is mostly water, so if you don’t eat too many, then you will not take in too many carbohydrates or calories.
“The second bad reputation is their high glycemic index reported by some studies. However, potatoes are not that dense, so the glycemic load from an average serving of potatoes is actually not more than any other carbohydrate food.” Potatoes tend to have low-medium to high glycemic loads, with the exact value depending on things like the food preparation method, the cultivar and where the potatoes were grown.
The project, which runs from 2014 to 2017, could help boost potato’s health reputation. “The project’s overall objective is to identify early maturing, coloured potato varieties with health benefits (low glycemic index and glycemic load, and high phytochemical antioxidants) and acceptable sensory qualities, that are affordable, accessible to low- and middle-income families, provide a price premium to growers, reduce importation, and provide retailers with local food,” Pinhero explains.
The project focuses on cultivars that are both early maturing and coloured because both traits tend to be associated with enhanced nutritional attributes.
“Early maturing potato cultivars usually have a lower dry matter and low glycemic index due to a different starch structure. So early potatoes may be good candidates for low glycemic load foods,” Pinhero says.
“Potatoes generally contain many phytochemicals, such as various polyphenols, flavonols, anthocyanins, carotenoids, vitamins, et cetera. Coloured varieties, especially based on their flesh or skin colour, contain substantially higher amounts of these phytochemicals. These phytochemicals, which act as antioxidants, have [been linked to] many health benefits, such as providing anti-inflammatory effects and protection from cardiovascular diseases, many cancers and diabetes.”
According to Pinhero, early potatoes receive a premium price compared to late maturing varieties, but in Ontario at present, early fresh market potatoes are limited to white varieties. “The red and yellow varieties currently grown in Ontario don’t mature until September, creating a need for imports.”
Along with Pinhero and Yada, this collaborative project brings together several other researchers with diverse expertise, including Qiang Liu, Rong Cao and Benoit Bizimungu with Agriculture and Agri-Food Canada (AAFC), and Alan Sullivan and Andreas Boecker from the University of Guelph. The project’s industry partner is Grand Bend Produce based in Grand Bend, Ont.
The researchers are currently testing 14 varieties, including two advanced lines developed by AAFC’s Fredericton Research and Development Centre. Four of the varieties have coloured flesh and skin, five have either coloured skin or flesh, and the rest have either white or creamy skin and flesh colour.
They are evaluating each variety for protein, total starch, various starch fractions, available carbohydrates, total polyphenols, anthocyanins, flavonols and antioxidant potential.
“The various starch fractions – such as rapidly digestible starch, slowly digestible starch and resistant starch – are evaluated to estimate the glycemic index and glycemic load. The total starch and starch fractions, especially the slowly digestible and resistant starch, are very important as they affect human health by reducing the glycemic load. For example, resistant starch acts as a fibre,” Pinhero explains.
Once the researchers have identified which of the varieties have the best nutritional qualities, they will conduct a sensory analysis of those varieties for consumer acceptance. As well, they are conducting marketing studies in collaboration with Boecker.
So far, they are making good progress on the nutritional analyses. “We have analyzed the various starch fractions and the estimated glycemic index and glycemic load. We have identified 11 varieties that have low-estimated glycemic load, and three that have medium-estimated glycemic load,” Pinhero says.
The data from the project’s first year show Purple Fiesta, Carling Ford, Ciklamen, French Fingerlings, Red Thumb and Yellow Star had the lowest values for estimated glycemic index and glycemic load. Next, the researchers will be repeating the analysis of starch, glycemic index and glycemic load, but with fewer varieties and different cooking methods, and they’ll be conducting the phytochemical analysis.
“We are excited that this research will bring out potato’s many healthy characteristics so the consumer can make an informed decision of a healthier food choice and the industry will also benefit from it,” Pinhero says.
She sees many potential benefits from the project for growers, retailers and consumers. Ontario growers will have more choices for early maturing cultivars, along with more opportunities for obtaining the premium price for early potatoes. And, at the same time, they’ll have more choices for nutritionally superior cultivars desired by health-conscious consumers. Retailers will have access to a greater variety of locally produced early potatoes and those varieties will be more nutritious. “Availability of [local] early maturing, coloured potatoes with health-promoting bioactives, high antioxidant potential, and low glycemic index and glycemic load, would benefit the table potato market, potentially expanding the [Ontario] market by $6.6 million,” Pinhero says.
The information resulting from the project could be used in efforts to educate the public about the nutritional value of potatoes. Such efforts could contribute to an improved health reputation for potatoes and to increased potato consumption in Canada over time.
Consumers will benefit from more nutritious, low-cost food options. “A recent study on vegetable cost metrics in the United States shows that potatoes and beans provide the most nutrient value, thereby providing affordable, healthy vegetables for low- and middle-income families,” she notes. “Along with lifestyle changes, these healthy potatoes could be part of a variety of healthier food choices for prevention of obesity, Type 2 diabetes, coronary heart disease and several forms of cancer.”
Funders for this project include the Ontario Ministry of Agriculture, Food and Rural Affairs, the Potato Cluster 2 of the AgriInnovation Program of Agriculture and Agri-Food Canada, and the Ontario Potato Board.
A New Brunswick researcher says that despite the common perception that water and wind are responsible for erosion, tillage erosion is actually the leading cause of soil degradation in most cultivated fields in Canada.
Li Sheng, a hydrology/croplands and water management expert with Agriculture and Agri-Food Canada, has been analyzing the causes of erosion in order to develop management recommendations.
His message is surprisingly positive.
“Our perception is that soil erosion is really bad in Eastern and Atlantic Canada, but it’s actually getting much better,” he says. “People are more aware of erosion, and a lot of structures have been put in place to reduce it. However, in critical times, you’ll still see a lot of erosion happening and erosion remains the number one cause of soil degradation in many fields.”
For the past few years, Sheng has led a research team conducting several studies in erosion. One study comparing water, wind and tillage erosion, conducted in partnership with David Lobb, a University of Manitoba soil researcher, found that wind erosion is much less severe than water erosion in Eastern Canada. While it is more damaging in Western Canada, wind erosion in most fields is still not at the same level as water or tillage erosion.
The most worrying aspect of erosion on the East Coast, says Sheng, is the combined effect of water and tillage erosion.
These days, Sheng’s team is testing the hypothesis that water and tillage erosion work together to create a more severe problem – that tillage erosion actually offers a mechanism for soil to leave the field by water erosion.
“If you have gullies going down the field, cutting through the soil to the edge of the field, if you till the field and fill those gullies in, in the next major rainfall event, all of this loose soil will be washed away,” he explains. “We are thinking that in Eastern Canada this is probably one of the major mechanisms of the transportation of sediments going out of the field.”
In the summer of 2015, Sheng and his team set up multiple research sites on Prince Edward Island and in New Brunswick. A gauging station on the edge of the field will measure sediment and take water samples. The research team also put cameras and erosion pins at different points in the fields to analyze surface changes due to erosion.
The study will run three years to allow the researchers time to collect solid data during potato rotation schedules.
Maintaining erosion structures
Sheng’s team has developed a list of best management practices to help growers minimize erosion. Conservation tillage and mulching are both key strategies, along with erosion management structures such as terracing and grassed waterways.
The latter might not be commonly used in Western Canada, but Sheng says it’s difficult to find potato fields on the East Coast that do not employ them.
The problem is a lack of maintenance.
“A lot of these structures are not very well maintained – there’s certain maintenance that has to be done to keep them functioning,” Sheng says.
Diversion terraces (sometimes called contour terraces) are one good example. On hilly land, diversion terraces break up long, sloping fields into smaller sections with shorter slopes, to slow down and divert runoff. “The longer the slope, the higher the water erosion, and the greater potential for eroded soil to be carried away by that high-power runoff,” he says. Terracing can vastly mitigate this problem. But growers should ensure they use terraces to their maximum potential – and don’t cut corners.
“Above the terrace berm, where the water comes down, there is supposed to be a one- to three-metre-wide channel, or runoff ditches, to allow runoff to flow at a non-erosive speed and sediments to deposit. However, many farmers will farm right to the edge of the berm, because allowing it means a loss of acreage and total production,” Sheng says.
Sometimes farmers are slow to clear out runoff ditches, but once filled, they lose their function. Runoff during heavy rainfall events can cut across the terraces.
Another example is the use of grassed waterways as informal roadways for field access, Sheng says. Grassed waterways are used as roadways “by maybe 90 per cent of farmers,” resulting in severe soil compaction, which can lead to reduced water infiltration and reduced function of grassed waterways on erosion control.
But the number one cause of soil erosion in many fields – tillage erosion – is the problem growers should focus on addressing.
“Some farmers do recreational tillage – when they have some free time, they like to go out in the field and do additional tillage that is not needed,” Sheng says. But growers should reduce disturbance to the soil as much as possible, which means eliminating unnecessary tillage, and any other unnecessary disturbances during seeding or harvesting.
“Reduce the frequency of tillage, the intensity of tillage, and the variability of tillage – the speed and depth,” he says. “Keep it as uniform as you can. Controlling speed and depth across the landscape will reduce tillage erosion.”
Most of all, growers should take a “landscape perspective” to erosion control, Sheng says, considering the entire system rather than individual fields and strategically employing best practices.
Careful management of irrigated potato crops over the long-term may help maintain crop productivity and nutrient availability within acceptable levels for agricultural production. This is the conclusion Agriculture and Agri-Food Canada (AAFC) researchers reached when they did a field experiment the year after completing a long-term irrigated potato rotation study in Brandon, Man.
During that initial 14-year rotation study, Ramona Mohr, a sustainable systems agronomist at AAFC, worked with a team of researchers to identify economically and environmentally sustainable rotations for irrigated potato.
From 1998 to 2011, Mohr and her colleagues grew six different rotations: potato-canola, potato-wheat, potato-canola-wheat, potato-oat-wheat, potato-wheat-canola-wheat and potato-canola (underseeded to alfalfa)-alfalfa-alfalfa, and looked at their effects on various factors including crop yield and quality, diseases and weeds, soil quality and economics.
“Generally accepted management practices were used during the 14-year rotation study,” Mohr says. “We soil tested on an annual basis and adjusted our fertilizer management practices accordingly.”
In the year after the rotation study ended, the researchers conducted a follow-up study to assess the impact preceding rotations had on phosphorus, potassium and micronutrient concentrations in the soil, as well as on soybean yield, quality and nutrient concentration.
For the follow-up study, the group picked a glyphosate-tolerant variety of soybean as an indicator crop to try to minimize possible confounding effects of the previous rotations with respect to disease, weeds and nitrogen.
It was a unique opportunity to study the relative effects preceding rotations have on crop productivity and nutrient status of the plant-soil system, given the limited information available for Western Canada.
“This rotation study was one of only two longer-term irrigated potato rotation studies conducted in Western Canada over the past couple of decades,” Mohr says.
Taking multiple soil samples from each rotation in the spring of 2012, the researchers were able to compare them with samples taken in 1997 at the beginning of the long-term study. They discovered that the soil nutrient levels and the yield and quality of the soybean crop were all typical of the region.
“We saw some differences in nutrient levels among the different rotations, but no substantial depletion or build up of nutrients, and no large differences in soybean yield among the rotations,” Mohr says.
Preceding rotations affected soybean yield to a limited degree. Soybean yield was six per cent higher following the potato-oat-wheat rotation than the potato-canola-wheat rotation, although the reason for this difference wasn’t clear.
“We also noticed when soybean followed potato, it had a slightly higher yield than following cereals or canola, we suspect, because of greater availability of water because the potato crop was irrigated and none of the other crops were,” Mohr says.
The samples also showed that where preceding rotations included alfalfa, seed protein increased and oil concentration decreased. The researchers believe the limited yield differences may have been due, in part, to the selection of soybean as an indicator crop. This likely minimized the differences among rotations arising from disease, weeds and nitrogen. Soybean had not been used in the rotation study and so was not susceptible to those diseases that had built up in the preceding rotations. Also, it is a nitrogen-fixing crop that could supply its own nitrogen. As well, by selecting a glyphosate-tolerant soybean, weeds could be effectively controlled regardless of the previous rotation.
For nutrients, the researchers looked at phosphorus and potassium in the top 15 centimetres of the surface soil and found they fell within the same general range of what they saw in 1997.
Soil test phosphorus was slightly higher except for the rotation that included alfalfa hay. That rotation saw a reduction of both phosphorus and potassium, which the researchers determined was likely a result of the high nutrient removal rates of alfalfa hay and their fertilizer management practices during the long-term study.
For example, Mohr says they applied phosphorus in the alfalfa establishment year, but not potassium because soil levels did not call for it. “When we saw a decline in soil potassium levels, we started applying potassium at that point.”
Soil test phosphorus levels were also found to be higher in the shorter rotations. “The two-year was greater than the three-year was greater than the four-year rotation,” Mohr says. Again, the researchers attribute this to their fertilizer management practices since they applied a higher rate because they broadcast the fertilizer in potato, adding more phosphorus than the potato crop removed.
“The more frequently we grew potatoes, the higher the soil test level we tended to see,” Mohr says. “Although we saw some difference in soil test levels, again they were within the range we see in agriculture fields.”
Mohr and her colleagues also looked at micronutrients during their follow-up study. “The site had sufficient micronutrients for the crop so we didn’t need to add any fertilizer,” Mohr says, although certain of the fungicides applied to potato would have contained some copper or zinc. While the preceding rotation had minimal effects on soil copper and zinc levels, soybean established after the potato-canola-alfalfa rotations or directly following a potato crop contained comparatively higher seed copper and zinc concentrations.
This suggests, Mohr says, that including mycorrhizal crops, like potato and alfalfa, might have increased the availability of micronutrients to the following soybean crop. “The roots of potatoes and alfalfa form a relationship with mycorrhizal fungi in the soil, which may increase the availability of micronutrients. We didn’t measure mycorrhiza in this study, but we know that based on previous studies.”
The results of the follow-up study in 2012 do suggest that careful, long-term management of irrigated potato systems may help maintain crop productivity and nutrient availability within acceptable levels for agricultural production. However, Mohr stresses the impacts of disease, weeds and nitrogen fertility on crop growth may have been minimized because the researchers selected soybean as the indicator crop in this study.
“If producers were to grow other crop species, there might be a greater impact on crop productivity,” she says.
A potato extract that’s rich in beneficial compounds is looking very promising. In trials with mice, researchers at McGill University have found that this extract reduces weight gain and provides other important health benefits. Now, they hope to conduct clinical trials to see if the extract produces similar benefits in people.
In this research, Danielle Donnelly, a potato researcher in McGill’s department of plant science, has teamed up with Stan Kubow and Luis Agellon, who are both at McGill’s school of dietetics and human nutrition. The research had its beginnings in Donnelly’s research on genetic improvement of Russet Burbank, the number one processing cultivar in Canada.
Because Russet Burbank has limited fertility, traditional breeding techniques aren’t effective for developing improved lines. So, about 10 years ago, Donnelly and her research group developed a technique using tuber tissue to propagate plantlets that can differ genetically from the original tuber. These variants, called somaclones, can then be grown in the field and screened for various traits. Donnelly has produced about 800 Russet Burbank somaclones.
“I had been screening my somaclones of Russet Burbank for yield and processing characteristics after long-term storage, and doing the selections and realizing that the somaclone technology could be very helpful there,” Donnelly explains. “Then, in talking to Stan Kubow, I realized that we should also be looking at nutritional parameters because the processing industry, and the whole potato industry, needs to be more concerned about the health of their consumers.”
Donnelly and Kubow started collaborating on potato nutrient research. In one part of this research, they examined the mineral content of 16 cultivars, including chippers, fryers and table stock, grown at five locations. “We found there was a lot of variation between the cultivars. Potatoes are not created equal for minerals! Russet Burbank and Yukon Gold were particularly good,” Donnelly says.
They determined that one serving per day of Russet Burbank, Yukon Gold or Freedom potatoes provides a significant portion of the recommended daily intake for magnesium, phosphorus, potassium, copper, iron, selenium and zinc.
In another part of their nutritional studies, Donnelly and Kubow determined the antioxidant levels in her top 25 somaclones that were best for yield and processing traits. In potatoes, antioxidant activity comes from vitamin C, a number of polyphenolics and other compounds. Out of the 25 somaclones, they selected the four that had the highest antioxidant activity plus a range of polyphenolic compounds.
From this screening and selection work, Donnelly currently has four advanced lines moving toward registration. She hopes to register the best one or two of those lines later this year. “All four lines have high yield, three of them do better than the Russet Burbank control in fry tests, and all have very high protein and high antioxidant capacity,” she notes.
In a different aspect of the potato nutrient research, Agellon, Kubow and Donnelly investigated the effects of potato polyphenols on diet-induced obesity. The possibility that eating polyphenols might control obesity may seem surprising, but obesity actually has a connection with inflammation. Research has shown that obesity results in low-grade chronic inflammation due to the reaction of certain cells to excess nutrients and energy.
As a first step, Kubow and Donnelly grew 12 different potato cultivars for several growing seasons and compared their polyphenolic contents. They found that Onaway and Russet Burbank had higher and more consistent polyphenol levels than the other cultivars.
Next, using these two cultivars, the researchers made an extract containing a mixture of potato polyphenols. “The extract concentrates the active ingredients, making it more likely to see the biological effects we were interested in,” Kubow explains. One dose of the extract has about 30 times the amount of polyphenols found in a single potato. The main polyphenol in the extract is chlorogenic acid, which has been shown to have anti-obesity effects in some situations.
Then the researchers conducted a feeding trial with mice to evaluate the effect of the extract. “The mice were fed a diet that is similar to what many North Americans consume; it is high in calories, high in fat, and high in sugar content. We wanted to see if these polyphenols, when given to mice that are ingesting this high-fat diet, would help in preventing obesity,” Agellon says.
One group of mice was fed just the high-fat diet. A second group was fed the high-fat diet plus the potato extract. And a third group was fed the high-fat diet plus an equivalent amount of a purified single polyphenol, either chlorogenic acid or ferulic acid.
“We were intrigued by a number of studies that tested single polyphenols reported to be active in some systems but that were not as effective when used in a purified form; it seems that the purified compound had lost its potency,” Agellon explains. “We wondered if the desirable effect associated with a food like potato and the polyphenols that it contains, is because of a combination of the different compounds in the food.”
Their hypothesis was that each individual polyphenolic compound produces a small benefit for a particular area of the body, like the liver, but multiple polyphenols ingested together affect multiple pathways, producing a synergistic effect with major health benefits.
Agellon says the extract’s benefits emerged quite quickly in the trial. “Midway through the 10-week study, we could see which of the groups had received the polyphenol extract. They had less weight gain and were much more active than the mice receiving the high-fat diet by itself.”
Kubow adds, “This effect wasn’t because the mice didn’t like the diet and didn’t eat it. They were eating as much or more of the high-fat diet [as the other groups of mice]. Normally, mice respond just like humans – if they eat a lot of fat, they gain a lot of body fat and body weight. But to our surprise, the extract had quite remarkable potency in inhibiting that, regardless of how much they ate.”
The individual polyphenols were not quite as effective as the extract in reducing weight gain, suggesting synergistic benefits from the mix of polyphenols in the extract.
The researchers are excited by the extract’s potential human health benefits. Agellon notes, “The extract could be a wonderful tool to help people suffering from obesity.” To move forward on this, they need to conduct clinical trials to assess the extract’s fat-fighting effect in people. “We’ve got a lot of data supporting this effect in animal trials and in some culture trials, but clinical trials are the key, critical step toward commercialization,” Kubow says.
The researchers have also looked at the extract’s effect on another inflammation-related health problem: lung damage caused by air pollution. Kubow explains, “Inflammation is your immune system overreacting to various compounds, including pollutants. With air pollution, that overreaction causes damage in various tissues including the lungs. So our hypothesis was that the extract might be effective where people are overweight and exposed to pollutants at the same time.”
In this study, they fed two groups of mice a western-style diet, similar to the diet in the obesity trial but not quite as high-fat. For four weeks, one group was fed the high-fat diet, and the other group was fed the high-fat diet plus the extract. Then the mice were exposed to ozone for four hours, to replicate the effects of exposure to heavy smog. “We looked at their lungs 24 hours after that exposure because the body is continually overreacting with the inflammatory response. That allowed us to detect factors in the lungs associated with ozone damage and inflammation,” Kubow explains.
The results showed that the mice eating the potato extract had significantly less lung damage. “We think this study was an important first step to validate the use of this extract as a means of potentially having a supplement to combat air pollution, which would be the first such supplement,” Kubow says. “However, we need clinical trials for verification of the benefit in humans.”
Clinical trials are key
The researchers are currently seeking funding for clinical trials to see how well the extract fights obesity and lung damage in people. If those trials prove the extract’s effectiveness, then the extract could have commercial potential, for instance, as a dietary supplement or a cooking ingredient. So investment in the trials could be of interest not only to health agencies but also to the potato industry because of the extract’s value-added potential.
Donnelly sees a couple of ways the next steps in this research could help potato growers and processors. “First, there are the clinical trials, which would get a product out there. Secondly [with information on polyphenol levels in more cultivars] it could be that more potato growers could benefit because there is a lot of wasted potatoes – people growing small potatoes have big ones they can’t use, and big potato growers have little ones they don’t always know what to do with. It may be that some of these materials could be rescued from waste streams from processed potatoes. So there is a lot of potato that could be used for a product that no one has produced up until now, which is this extract.”
As well, a potato extract with proven health benefits might help enhance the health reputation of potatoes. Kubow says, “The public perception is that potato intake is bad for your weight, but we’re talking about potato decreasing the risk of overweight and obesity.”
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