SEED PRODUCTION IN Festuca hallii (Vasey) Piper: ECOTYPIC VARIATION AND PHYSIOLOGICAL MECHANISMS

Abstract

Plains rough fescue (Festuca hallii (Vasey) Piper)) is an important forage grass species in Western Canada. Seeds of this species are in high demand for forage production and habitat restoration. However, the supply of seeds is extremely limited owing to erratic seed production in time and space. Thus, seed producers require a comprehensive understanding of the factors that influence flowering and seed production in this species. This study elucidated the effects of autumn and spring temperatures and moisture conditions on flowering and seed production in Festuca hallii. Furthermore, the present study evaluated the morphological and phenological variation existing among the six ecotypes of Festuca hallii from Saskatchewan and Manitoba. Temperature and precipitation data as well as observations on flowering of Festuca hallii at the Kernen Prairie near Saskatoon, Saskatchewan between 1986 and 2010 were analyzed to examine the effects of temperature and moisture conditions on flowering and seed production. To assess the morphological and phenological diversity among the six ecotypes of Festuca hallii, seedlings were grown in the field and transplanted to the greenhouse in November. Plants not flowering in the greenhouse were vernalized under 5oC- 8 h light for 11 weeks. In another experiment, plants were subjected to temperature regimes of 15/5oC, 10/0oC and 5/-5oC with temperature regime having daylength treatments of 12, 8 and a gradually changing daylength from12 to 8 h. Colder than normal temperatures to normal temperatures and wet to normal summers and autumns favored flowering in the following year. Moreover, warmer than normal to normal temperatures in the spring also favored flowering. However, there was no clear pattern in spring moisture conditions that could distinguish between seed producing and non-seed producing years. The occurrence of freezing events in spring negatively affected seed production. Irrigation in late summer and autumn is recommended for seed production in Festuca hallii. Differences in morphological and phenological characteristics were evident among the ecotypes of Festuca hallii. Vernalization requirements also varied among ecotypes. Overall, 15/5 to 5/-5oC day/night temperature regimes with photoperiods between 12 and 8 h were effective in inducing flowering. Seed mass was highest under 5/-5oC and 12 h to decreasing daylength. Flowering frequency was highest in the seedlings of MCL ecotype, which were vernalized in the field and again were subjected to the similar vernalization treatment. However, the overall flowering frequencies were higher in both MCR and MCL ecotypes under different artificial vernalization treatments. Because of the variation in growth and vernalization requirements among ecotypes, seed sources should be an important consideration for habitat restoration and forage production.