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Genotype x Environment interaction for oat grain fill

Principal Investigator:

A.R. McElroy

Research Institution: 

PhytoGene Resources Inc.


April 2016 – March 2017


  • Determine the level of Genotype x Environment interaction (GxE) for the frequency of unfilled oat kernels.
  • Establish whether multiple testing sites are necessary to screen for the unfilled oat kernel trait.
  • Provide insights on environmental factors that influence this trait if environment is found to be significant.


  • The greater understanding of the factors affecting the frequency of unfilled kernels will allow breeders to generate varieties with increased yield and grain quality.
  • The reduction of unfilled kernels through breeding will improve test weight and will give farmers better access to milling and higher-value feed markets.
  • The improvement of oat yield and quality will increase its profitability and will make oat more desirable to be planted in crop rotations, therefore having a positive environmental impact through increase in biodiversity associated with multi crop rotations.

Scientific Summary:

Oat is recognized as an excellent rotation crop, and a valuable cash crop, particularly in the cooler, northern regions of Ontario. Good grain fill is essential for high oat yield and quality. Unfilled kernels – ‘kernels’ in which floral or groat development was arrested prior to grain fill, resulting in empty hulls – can decrease yield potential and grain quality. Studies by PhytoGene Resources have shown that the number of kernels set per panicle and the frequency of unfilled kernels are the two most important yield components in oat.

It is well known that most oat contains some unfilled kernels. This phenomenon is generally considered to be a result of plant stress, either disease or environmental, although there are no studies to confirm this. However, past research at PhytoGene Resources revealed that the unfilled kernels are related to developmental problems during panicle formation rather than to stress during grain fill.

Variation among oat lines has also been noted, indicating that this trait is heritable, but the effects of environment or the interaction of genotype and environment (G x E) is not known. It is important to understand these effects in order to develop effective breeding protocols, and in particular, whether screening in a single environment is adequate.

The objectives of this study were to determine the level of GxE, and thus the necessity of multiple-site screening, and to provide insights of the role of environment on this parameter.

One hundred elite oat lines were grown at three contrasting Ontario sites, Cumberland, Mimosa and New Liskeard. Panicles from each plot were threshed, and basic yield component parameters were measured: total kernel set, % unfilled kernels, mass (TKW) of filled kernels and yield per panicle.

The season was characterized by extreme early drought at Cumberland and Mimosa, and dry conditions at New Liskeard. Seed set was extremely low at Mimosa (mean of 35 per panicle) but the occurrence of unfilled was exceedingly high – a mean of 81%. These data could not be used in the Genotype x Environmental analysis, but they clearly indicate that early-season moisture/heat stress is a major factor influencing this trait.

The project established that early-season heat/moisture stress can result in high levels of unfilled kernels, thereby reducing yield potential and quality. Lines differed in their levels of unfilled kernels, but there was a highly significant interaction between lines and site. Multiple environment testing is advisable.


1) Early-season stress is a major factor responsible for the presence of unfilled kernels. Extreme cases can result in complete crop failure, with no filled grain in a normal looking crop.

2) There is extensive genetic variation for resistance to this stress, but there is also a significant genotype x environmental interaction. Therefore, screening in more than one environment is advisable.

Associations among yield components (including % unfilled) and yield were documented through this project. That information will be of benefit to plant breeders in developing selection strategies.

External Funding Partners: None

Project Related Publications:

King, Carolyn. 2017. Boosting oat yields by filling more kernels. Top Crop Manager.