Selection of a perennial grain for seed productivity across years: intermediate wheatgrass as a test species

Development of perennial grains is being promoted to aid in moving agriculture towards sustainable production. How long does it take to identify perennial yielding ability? Intermediate wheatgrass [Thinopyrum inter-medium (Host) Bark. & Dewey] nurseries were transplanted in 2011 (4500 plants) and 2012 (1000 plants) at Carman, MB. Productive, healthy plants were harvested on a yearly basis. Intolerance to late frosts after spring regrowth initiation in 2012 (approximately 55% of the plants) and in 2014 (the entire 2012 nursery) led to these plants not being harvested. Mean yield plant(-1) was 37.25, 66.70, and 57.81 g for the 2012, 2013, and 2014 overall harvests, respectively. Individual plants showed divergent seed yielding patterns across years, especially with respect to the third harvest year. A number of plants were identified that had consistent relative seed yields over the 3 yr of harvest for the 2011 nursery. Linear regression indicated that the first year of seed production was a poor indicator of relative yield potential over all 3 yr (R-2 = 0.238) amongst the highest overall yielding plants, with 2013 and 2014 having greater predictability. Variability in yield in the third reproductive year indicated that the third year is required to identify highly productive individuals for three consecutive seed harvests.