Comparison of the Shattering Characteristic of Glyphosate Resistant Canola with a Non-Resistant Variety

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David L. Esplin and Dr. Larry S. Jeffery, Agronomy and Horticulture

Shattering is a characteristic of many plants that are weeds in food crops. Several examples exist where a weed and a cultivated crop are different due to their shattering characteristic. For instance, Proso millet(Panicum miliaceum), a cultivated crop used for birdseed, is the same genus and species as wild proso millet. The main difference is that wild proso millet shatters more easily than the cultivated variety. Similarly wild cane (sorghum bicolor) and forage sorghum are classified as the same genus and species. The wild cane is considered a weed because it tends to shatter more than the sorghum.

Canola, an oil crop of gaining popularity, could become a weed if its tendency to shatter were to increase. In the process of genetic alterations to produce a glyphosate resistant plant, it is possible the shattering characteristics could have changed. The objective of this study was to determine if the genetically altered canola is prone to any increase in shattering compared to its non-resistant counterpart.

Two populations of canola were grown in the greenhouse. The two populations were genetically identical, except one population was resistant to glyphosate and the other was not resistant. Fifteen pots of each population were grown. The pots were seeded heavily then thinned to two plants per pot. The populations were grown under identical climatic and cultural conditions. At maturity, the seedpods were clipped off the plants and allowed to equilibrate for ten days at 20 degrees Celsius and 50 percent relative humidity.

Twenty pods from each population were placed in a plastic sack with four golf balls. The sack was closed and the shaken for 5 seconds. The sack was opened and the broken or cracked pods were counted. This method was repeated again after 5 seconds, 10 seconds, and 20 seconds. Three replications of each population were tested with this procedure. The whole procedure was then repeated. The number of pods that shattered were averaged from the two repetitions. The following table shows the results of the test. The average number of pods broken after each event is recorded in the table.
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The results were then statistically analyzed utilizing the SAS statistical software system. A repeated measures analysis with multiple measurements taken on each replication was used to analyze the data. It was determined that there is no significant difference in shattering characteristic between the resistant and non-resistant populations of the tested caola (p-value = .3710). Therefore, this data suggests that the genetic transformation was precise enough to change the plant’s resistance to glyphosate without affecting the shattering characteristic. Genetically engineered glyposate-resistant canola is not prone to any increase in shattering characteristic compared to its non-resistant counterpart. Therefore, it will not become a weed in field crops.

References

  • Morgan, C. L., Bruce, D. M., Child, R., Ladvrooke, Z. L., Arthur, A. E., 1998. Genetic variation for pod shatter resistance among lines of oilseed rape developed from synthetic B. napus. Field Crops Research 58, 153-165.
  • Anderson, Wood Powell. 1996. Weed Science: principles and applications. West Publishing Company, St. Paul, MN.