Soil type and moisture level influence on Alamo switchgrass emergence and seedling growth

Attempts to establish lowland types of switchgrass (Panicum virgatum L.) in the Lower South have frequently been unsuccessful. A greenhouse study was conducted to determine the influence of soil texture and moisture on 'Alamo' switchgrass emergence and seedling growth. Soils used were a very fine sandy loam, loamy fine sand, silt loam, and clay that were watered every 3 to 4, 7, 10 to 11, or 14 d. Emergence was recorded daily for the first 28 d and seedlings were harvested at 6 wk to determine survival and seedling traits. The study was initiated on 30 March 2001 and repeated on 29 May and 24 July. Run date caused significant (P less than or equal to 0.001) interactions for all measurements with soil series and watering interval because of increasing greenhouse temperatures with each succeeding run. Watering interval affected emergence only at the 24 July run with emergence decreasing as watering interval increased. However, watering interval of at least 7 d was necessary for greater than 90% seedling survival in all soils. Only the clay soil consistently had good seedling survival (greater than or equal to 94%) at all watering intervals. Shoot stage and weight and root stage and weight decreased as watering interval increased. These seedling traits were usually higher in the loamy fine sand and very fine sandy loam if watered at least every 10 d. The trend for root/shoot ratios was to increase as moisture became limiting because shoot weight decreased faster than root weight. Rainfall occurring at greater than 10 d intervals is one of the factors for unreliable switchgrass establishment on sandy soils in the Lower South.