Grass Seedling Emergence, Morphology, and Establishment as Affected by Planting Depth

The seeding depth of grasses affects emergence and adventitious root development. Seedling root morphology and development should be considered when determining planting depth for forage grasses. A field study was conducted on a Kennebec silt loam (fine-silty, mixed, mesic Cumulic Hapludolls) during June to August 1985 and 1986 to investigate the effect of planting depth on seedling emergence, morphology, and establishment of smooth bromegrass (Bromus inermis Leyss.), big bluestem (Andropogon gerardii var. gerardii Vibnan), indiangrass [Sorghastrum nutans (L.) Nash], and switchgrass (Panicum virgatum L.). Seeds were planted by hand to insure seeding depths of 1.5, 3.0, 4.5, and 6.0 cm. Emergence percentage decreased with increased planting depth for all grasses except switchgrass, which had similar percentages at the 1.5- and 3.0-cm planting depths. Coleoptile length and seedling crown depth were positively correlated with actual planting depth in smooth bromegrass, while subcoleoptile internode length was positively correlated with actual planting depth in big bluestem, indiangrass, and switchgrass. Indiangrass differed from big bluestem and switchgrass, since its coleoptile length was positively correlated with actual planting depth. Smooth bromegrass may have the potential of increased adventitious root development due to deep placement of the seedling crown in the soil. Big bluestem, indiangrass, and switchgrass do not have the potential of increased adventitious root development as seeding depth increases, since there was no correlation of seedling crown depth with actual planting depth. Rapid increase in adventitious root number of big bluestem, indiangrass, and switchgrass was noted after three or more consecutive days of rainfall after 4 wk from planting