Early seedling growth and forage production of diploid and tetraploid crested wheatgrass and Russian wildrye cultivars

Abstract

Cultivars selected for improved seedling vigour may also differ in seedling growth and subsequent forage production. The objective of this project was to compare three cultivars of crested wheatgrass (CWG) and four cultivars of Russian wildrye (RWR) for seedling growth in a greenhouse (GH) trial and two field trials when seeded at 15, 30 and 45 mm depths. Cultivars were Goliath, Kirk and Parkway CWG and SCR39903, Swift, Tetracan, and Tom RWR. Seedling emergence, tiller number, and seedling biomass were determined at 28 d after seeding (DAS) in all three trials. In addition, forage dry matter (DM) yield was determined for 2 yr in the field trials. Small-seeded diploid Parkway crested wheatgrass had reduced emergence at 45 mm seeding depth compared with larger-seeded tetraploid Kirk and Goliath. Goliath had reduced tillering compared with the other two CWG cultivars. The emergence of Tetracan tetraploid RWR was greater at deeper seeding depth than diploid cultivars, SCR39902, Swift and Tom in Field Trial 2, but not in Field Trial 1 and the GH trial. Seedling tiller number of Tetracan RWR was less than that of the other three cultivars. Two-year total CWG forage DM yield in the field was best correlated to emergence. In contrast, 2-yr total RWR forage DM was best correlated to seedling tiller number in GH and Field Trial 2 despite the low tiller numbers at 28 d after seeding. Field emergence of Russian wildrye did not appear to be limiting to seedling establishment in contrast to previous reports. Selection in RWR should include seedling tiller number in combination with seedling emergence in order to improve both seedling vigour and forage productivity. Key words: Establishment, tiller, emergence, forage yields, seedling depth