Murray Hartman’s Reflections from the 2016 Canola “science-o-rama”

 

The Alberta Canola Industry Meeting / Research Update was resurrected on April 6th, 2016, under a new handle “science-o-rama”.  The event was hosted by the Alberta Canola Producers Commission (ACPC) and held at the Renaissance Edmonton Airport Hotel.

 

For the speakers and topics, I mainly targeted research projects funded by ACPC and / or ACIDF which have not been communicated widely in traditional extension events such as FarmTech and Agronomy Update.  I invited speakers from the cross section of the various agriculture research providers in Alberta:  Agriculture and Agri-Food Canada; Alberta Agriculture and Forestry; Alberta Innovates; universities, applied research associations and private industry.

 

 

After briefly describing the western Canadian pollination industry, several previous studies from Quebec and internationally were mentioned where additional bee hives have increased canola yield.  The limitations of previous research led her to design and conduct an Alberta research project.  Using tent material that excluded wind and pollinators versus only wind at Lethbridge, she found that canola harvest index (a proxy for yield) was reduced significantly when wind was restricted.  The prevalence of wind in southern Alberta means that insect pollination for commodity canola yield plays a less prominent role than in other areas.

 

The second aspect of her project was to assess the pollinators present in commodity canola fields at Lethbridge and Beaverlodge, with honeybee hives placed at field edge – pollinator abundance, distribution in field and relationship to yield were measured.  The top 3 pollinators visiting canola flowers were honeybees, flies and hoverflies species.  Honeybee visits increased with higher stocking rate and closer to hive location.  Wild pollinator abundance also declined in the middle of fields.  Yield data analysis is underway.

 

The third aspect of her project is studying the pollinator behavior in hybrid seed production fields.  An MSc student from the University of Calgary (Riley Waytes) observed flower visits at 30 fields near Lethbridge in 2015 and 2016.  The amount of pollen deposited on stigmas by different pollinator species, and the frequency of visits will be determined.  Preliminary results show that the female leafcutter bee deposits the most pollen per visit.   Information generated by this project may suggest ways to use various pollinators more efficiently.

 

 

Although canola and other plants of cabbage family do not normally form mycorrhizal root associations, a recently discovered fungus Pirifomospora indica is able to colonize roots of brassica plants. This project involved indoor controlled environments to study the growth of inoculated canola under various stresses (low N, P, drought, flooding, low temperature or salinity).  Root inoculation with P. indica increased shoot and root growth of canola seedlings and the effect was enhanced under higher N levels and by presence of organic carbon in the growth medium.  Inoculation improved canola growth and yield under drought and low N or P fertility, depending on plant stage when drought occurred.  Flooding, salinity and low temperature tolerances of canola were improved when inoculated.  A novel protocol has been developed that makes it possible to apply fungal inoculum on a large scale.

 

 

The use of plant growth regulators to ameliorate the effects of abiotic stress such as heat in field crops is an active research topic.  Among the classes of plant growth regulators, auxins show some promising characteristics in regulating abiotic stress effects related to plant growth and yield.  This project studied the effect of auxin application on canola seed yield under heat stress and non-stress conditions.  One natural auxin and one synthetic auxin were compared in the greenhouse and under field conditions (4 sites in Alberta and Saskatchewan over 2 years). Several rates of the auxins were tested at green bud stage and 1 week after green bud stage, and a heat stress treatment was included in the greenhouse study.   Substantial yield increases were obtained with one of the auxins at certain concentrations under heat and non-stressed conditions in the greenhouse trials.   In the field trials, auxins statistically increased yield at two site years but at different concentrations than the greenhouse study.  Differences in cultivars used and maximum temperature following the hormone application in the field study likely led to varying optimal auxin analog and concentrations.

 

 

Sclerotinia is a serious disease in canola yet timely, rapid, and accurate forecasting is not currently available.  One solution could be an in-field biosensor for real-time sclerotinia spore detection with specificity and accuracy.  Design and testing of a miniature (nano) bio-sensor utilizing antibody-antigen system was described.  As few as 5 spores could be detected and this was less than the minimum number of spores over 24 hours needed to initiate disease in a growth chamber.   There was a good correlation between the number of spores and disease severity in the growth chamber.  The signal from the biosensor was capable of being transmitted to an iPhone, and thus a convenient, user-friendly interface for the field could be built.  The next step is to calibrate this under field conditions.

 

 

The development of clubroot resistance screening for canola against the initial Alberta pathotypes was outlined.  The successful introduction of clubroot resistant canola hybrids was adopted, and quickly became the primary tool used to manage clubroot in farm fields.  Longer rotation breaks from canola did not generally occur as growers relied mainly on variety resistance, in spite of risks for resistance erosion.   The lack of adequate rotation breaks for clubroot resistant canola (poor stewardship) led to pathogen shifts and the first cases of resistance failure in 2013.

 

The procedure used to identify a pathogen shift was described, and how it was confirmed that the new pathotype from 2013 was able to overcome resistance in all the commercially available varieties in western Canada.  The new strain was classified as pathotype 5 in the Williams differential set, but it was obviously different because it could infect canola varieties resistant to previous pathotype 5 isolates.  This indicates the weakness of various international clubroot differential sets to distinguish all clubroot strains.  Current resistant canola varieties showed low disease reaction to pathotype 5x at inoculum concentrations of 5 x 103 spores/g of soil and below, and high disease with 5 x 105 or more spores/g of soil.  Additional field surveys were conducted in 2014 and 2015 to look for additional fields with pathogen shifts.  From 27 suspect fields in 2014, 16 were confirmed to have pathogen shifts that defeated variety resistance.  These fields were located throughout the clubroot infested areas of Alberta which suggests that pathogen shifts are occurring independently.  A Canadian clubroot differential set has been assembled from the various international differential sets and it is being assessed for its ability to distinguish old and new strains in Alberta.  There were 9 distinct new pathotypes identified from the 2014 cases that defeated resistant varieties.   The 2015 survey has confirmed another 24 fields with pathogen shifts, but the pathotyping analysis is not complete to determine how many additional new strains have occurred (preliminary analysis suggests a few, not as many as 2014).  After the combined 2014 and 2015 results are analyzed, the Canadian clubroot differential set may be settled and a naming system for pathotypes suggested (to avoid vague names such as 5x, 3x, 3y, 3z etc.).   The CDC North facilities (greenhouse and field) for screening canola varieties and germplasm against the new pathotype 5X was described.  Research at CDC North indicates that genetic testing (PCR) can distinguish the pathotype 5 and 5X strains from other strains found in Alberta.

 

Rotation studies using large tubs showed that resting spore numbers and clubroot disease severity declined while canola yield increased with 2 alternate crops between canola crops compared to continuous canola.  Several years of greenhouse and field trials with Vapam to fumigate infested soil before planting canola were discussed.  Vapam reduced clubroot severity and improved canola growth and yield, but was deemed much too expensive for general large scale field applications.  Additional work with another soil fumigant (Basamid) found better canola growth in infested soil in the greenhouse than field trials.   Soil fumigation may be useful in isolated locations to mitigate clubroot hot spots, but it is expensive and requires specialized training for application.

 

 

The University of Alberta (U of A) program to search for clubroot resistance in the six closely related Brassica species was described.  A total of 275 accessions of six Brassica species were evaluated.  Resistance was found more frequently in turnip (B. rapa var. rapifera) and black mustard (B. nigra).   Limited resistance was found in B. napus (mainly in rutabaga types) and B. oleracea, and no resistance was detected in B. juncea and B. carinata.

 

Dr. Rahman then described the breeding and development of multi-genic clubroot resistant hybrid canola in partnership with Crop Production Services.  The CR gene 1 involved a major gene with good resistance to pathotype 3, and markers were developed to assist with breeding.  The CR gene 1 was used by CPS to create a Rf line (male parent) for hybrid seed production.     The introgression of CR gene 2 was more difficult since the parent source was not canola quality oilseed type.  After breeding to improve agronomic and seed quality traits and developing markers, the CR gene 2 was used by CPS to create a CMS line (female parent) for hybrid seed production.  These two lines with different clubroot resistance has produced the first hybrid variety (PV 580 GC) with true multi-genic resistance.    Tub tests at the U of A shows good resistance against the new pathotype 5x.  Breeding of improved CR cultivars carrying resistance to multiple pathotypes will continue and several improved hybrids are in the pipeline.