Russian Wildrye Seedling Development under Three Temperature Regimes

Abstract

Poor seedling vigor of Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski] has resulted in frequent establishment failures and deterred more widespread use of this grass. This study was conducted to ascertain coleoptile length and seedling emergence of Russian wildrye under three temperature regimes at a 70-mm planting depth in a Parshall fine-sandy loam soil (coarse-loamy, mixed, superactive, frigid Pachic Haplustolls; bulk density = 1.3 g cm−3) and to compare seedling development of four tetraploid populations with two diploid check cultivars. Diurnal temperatures (12/12 h, both dark) were 7/10°C (low), 13/16°C (medium), and 19/22°C (high). Soil water was maintained near field capacity. Coleoptile lengths for the low-, medium-, and high-temperature treatments averaged 48.3, 50.2, and 55.5 mm, respectively. Low and sporadic seedling emergence of ‘Vinall’ at all temperature treatments resulted in a significant (P ≤ 0.01) entry × temperature interaction. Entries had similar ranking for emergence within each temperature regime, and all entries but Vinall had increased emergence in response to increasing temperatures. Seedling emergence from a 70-mm planting depth was dependent on elongation of both the coleoptile and first seedling leaf, and diploid entries failed to emerge in most instances. Seedling emergence at the low-, medium-, and high-temperature treatments averaged 4.5, 14.5, and 16.5%, respectively, for the two diploid check cultivars and 16.5, 27.0, and 37.0%, respectively, for the four tetraploid populations. Tetraploids had greater seedling establishment potential than diploids, but any advantage for early-spring seeding would be due to factors other than soil temperature.