Crested wheatgrass is a deep-rooted bunchgrass, which is tolerant of drought and extreme winter temperatures common in Saskatchewan. It is among the first perennial grasses to green up in the spring, and is of high quality at early growth stages. However, crested wheatgrass generally matures early, and its forage quality rapidly declines with plant maturity. Therefore, there is a need to develop new crested wheatgrass cultivars with a better pasture utilization potential. The objectives of the study were: (1) Develop later maturing crested wheatgrass lines with high forage yields to extend the spring grazing season in Saskatchewan, 2) Evaluate crested wheatgrass lines for forage nutritive value at mature growth stage and select populations with higher nutritive value, 3) Evaluate new accessions and cultivars of hexaploid crested wheatgrass under Saskatchewan growth conditions to explore their potential use.

A field trial was established with 45 crested wheatgrass accessions using a randomized complete block design with four replications at the Agriculture and Agri-Food Canada (AAFC) Saskatoon Research Farm in July 2014. Data were collected for agronomic characteristics, forage quality, and ploidy level in 2015, 2016 and 2017. On the basis of DNA content (pg 2C^-1 = DNA content of diploid somatic nucleus), mean DNA content was 14.12 pg 2C^-1 for diploid, 28.02 pg 2C^-1 and 39.48 pg 2C^-1 for tetraploid and hexaploid crested wheatgrass, respectively. Among the 45 accessions, there were 8 diploid, 31 tetraploid, and 6 hexaploid. Plant maturity and other measured characteristics differed significantly among the ploidy levels. Days to heading, plant height, leaf-to-stem ratio, forage DM yield, leafiness, plant vigor and nutritive value (crude protein, neutral detergent and acid detergent fibers) differed among the accessions at flowering stage. In this study, days to heading had a positive correlation with leaf-to-stem ratio, indicating that selection for later maturity in crested wheatgrass may lead to an increase in leafiness. The late heading genotypes also showed higher forage yield. Based on agronomic performance and nutritive value, the 45 crested wheatgrass accessions were grouped into three main clusters. In conclusion, plant maturity varied within- and among- accessions, among ploidy levels, and selection for late maturity may simultaneously increase forage DM yield and leaf-to-stem ratio in crested wheatgrass. Information obtained from this study on agro-morphological traits, nutritive values and ploidy determination among the 45 crested wheatgrass accessions will be useful for future crested wheatgrass breeding.

Three new breeding lines of crested wheatgrass (S9611, S9617, and S9618) with late maturity and high forage yield have been developed from this study, which are currently evaluated in a replicated plot trial for maturity, forage yield, and quality. A new spaced nursery was transplanted in spring 2018 to further advance the selected materials. This project trained one M.Sc. student in forage breeding and provided research experience for four summer students in forage agronomy and management. Research results were presented at numerous industry meetings, and 1 scientific conference.

• Three new breeding lines (S9611, S9617, and S9618) of crested wheatgrass with later maturing and high forage yield were developed. The breeding line S9617 is selected for high hay yield, leafiness, and late maturity, S9618 is developed for superior forage yield and leafiness, and the breeding line S9611 is selected for late maturity and leafiness.
• A plant introduction (PI 486163) was isolated and inter-crossed to increase seeds for future use.
• Crested wheatgrass accessions are assembled into three main clusters for germplasm development and future plant breeding.
• Days to heading showed a positive correlation with leaf-to-stem ratio for the Canadian breeding lines and cultivars, indicating that selection for later maturity in crested wheatgrass may lead to simultaneously increase in forage dry matter yield and leafiness.
• High genotypic variation was detected within and among the crested wheatgrass accessions.
• Ploidy level of 45 crested wheatgrass accessions was determined.
• One M.Sc. student completed his degree.