Genetic variation for seed retention in accessions and genotypic lines of perennial ryegrass (Lolium perenne L.)

Seed shattering is a key constraint to improvement of seed yield in perennial ryegrass and, as a result, seed retention is an essential trait for breeding of this valuable crop. It is unclear whether sources of seed retention are available to plant breeders. Field studies were conducted near Corvallis, OR in 2 yr (2017-2018 and 2018-2019) to identify genetic variation for seed retention and to ascertain whether there was variation for phenotypic traits that may contribute to seed loss due to shattering. The field studies examined the values and variation in these traits in 40 diverse global accessions and genotypic lines within accessions. Plant mortality was high as only 21 of the original 40 accessions survived in sufficient numbers for analysis. The accessions and genotypic lines exhibited great variation in growth habit, spikelets per spike, seeds per spike, seed weight, spike length, and seed retention. Seed retention among accessions ranged from 27.1 to 78.7% with a commercial cultivar at 42.4% retention. For the most part, the values and variation observed in other characteristics were similar to that found in perennial ryegrass in other investigations, and some materials were representative of commercial cultivars. This study presents evidence that sources of higher seed retention than is found in commercial cultivars of perennial ryegrass is available from these accessions and could be used in the breeding of shatter-resistant cultivars.