Factors influencing crown placement of oats (Avena sativa L.)

Abstract

The depth of the grass crown nodes in the soil influences the susceptibility of the crown to environmental and management conditions which can affect grass establishment success and grain and forage yield levels. A controlled environment experiment was conducted to quantify the effect of planting depth (38 and 76 mm), temperature (25 and 10 degrees C), and light (full light [900 micromoles m(2) sec(-1)] and shaded at 55% full light [500 micromoles m(2) sec(-1)] on the elongation of oat (Avena sativa L. 'Valley') seedling internodes and the resulting final crown placement. The mesocotyl and 1st leaf internode increased in length with increased planting depth with no significant interactions. The length of the 2nd leaf internode increased more when developed under 25 degrees C temperatures than under 10 degrees C (significant temperature X depth interaction). However, the 2nd leaf internode elongated more under low light (55% full light) compared to full light (significant light X depth interaction). The 3rd leaf internode length was the same for the 38 and 76 mm planting depths when developed at 10 degrees C and under 55% full light. At 10 degrees C-full light and 25 degrees C-55% light, the deep planting depth resulted in increased 3rd leaf internode elongation, while at 25 degrees C-full light, the 3rd leaf internode was longer when developed from 38 mm planting depth (significant temperature X light X depth interaction). The ultimate elongation of these internodes resulted in the depth and structure of the final oat crown. This study points out the importance of naming and knowing each internode since the internodes do not respond in similar manner to environmental conditions. When all factors resulting in oat crown depth location and structure are considered, one expects crowns of oat seedlings developed under 10 degrees C to contain 4 nodes somewhat separated and crowns containing only 3 nodes more widely separated under temperature conditions of 25 degrees C. The most compact crown developed under reduced light conditions, from 38 mm planting depth, and a temperature of 10 degrees C. This information concerning the morphology of crown structure and location is expected to be similar for annual and perennial forage grasses with an oat type seedling morphology when seeded at similar temperatures, light intensities, and planting depths.