Birdsfoot Trefoil Management. I. Root Growth and Carbohydrate Storage

Abstract

AbstractManagement research is lacking for birdsfoot trefoil (Lotus corniculatus L.) cultivars adapted to the southeastern USA. This study was conducted to determine the effect of harvest interval and stubble height on root growth and carbohydrate storage of five birdsfoot trefoil entries. Two field experiments were conducted on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult) soil near Athens, GA. One experiment consisted of two birdsfoot trefoil entries (‘Fergus’ and GA l), three harvest intervals (21, 28, and 42 d), and two stubble heights (5 and 10 cm). The other experiment had five birdsfoot trefoil entries (‘AU Dewey’, ‘Dawn’, Fergus, GA 1, and ‘Norcen’) harvested on 21‐d intervals at three stubble heights (3, 5, and 10 cm). The AU Dewey and GA 1 entries, selected in Alabama and Georgia, respectively, had greater root weights and diameter than the northern‐developed cultivars. In the spring following 2 yr of harvest, root weights of Fergus and GA 1 were reduced 17 and 26%, respectively, when the harvest interval of the previous 2 yr had been 21 instead of 42 d. Raising the stubble height reduced fluctuations in carbohydrate reserves during regrowth. Total nonstructural carbohydrate (TNC) levels were greater in midseason when the stubble height was 10 instead of 3 cm. A positive correlation was found between spring herbage yields and the mean TNC level of the 2 preceding years. This correlation suggests a cumulative effect by carbohydrate levels on vigor of birdsfoot trefoil stands and management should be designed to maintain relatively high TNC levels.