YIELD AND YIELD COMPONENTS OF SPRING-SOWN WHITE LUPIN IN THE SOUTHEASTERN USA

Management studies must be conducted to realize the full potential of white lupin (Lupinus albus L.) as a grain crop for the southeastern US A. This experiment examined planting date, row spacing, and seeding ra te effects on grain and biomass yield of spring-sown white lupin. In 1 991 and 1992, held studies were conducted in northern Alabama on a Wyn nville fine sandy loam (fine-leanly, siliceous, thermic Glossic Fragiu dult), in central Alabama on a Hiwassee sandy loam (clayey, kaolinitic , thermic Typic Kanhapludult), and in southern Alabama on a Lucedale f ine sandy loam (fine-loamy, siliceous, thermic Rhodic Paleudult). Trea tments included three planting dates, three row spacings (17.5, 35, an d 70 cm), three seeding rates (17.5, 35, and 52.5 seeds m(-1)), and tw o cultivars (Primorsky and Ultra). Prevailing weather allowed only one planting date in northern Alabama in 1991 and 1992. In the second yea r of the study, only one and two plantings were successful in central and southern Alabama, respectively. Grain yields averaged 551 kg ha(-1 ) in 1991 and 604 kg ha(-1) in 1992. Grain and biomass yield was alway s highest in northern Alabama. Planting date affected grain and biomas s yield the most in central and southern Alabama in 1991. Decreased ro w spacing increased grain yields as much as 10 kg ha(-1) per unit decr ease in spacing. Grain yields increased as much as 19 kg ha(-1) for ev ery unit increase in seeding rate. Principal component analysis of yie ld components created factors branch, seed mass, and mainstem, which a ccounted for 57, 23, and 14% of the original variance, respectively. F actors branch and mainstem were highly correlated (r > 0.75) with grai n and biomass yield. Seed mass and mainstem were highly correlated wit h harvest index (r > 0.65). For the southeastern USA, high yields in s pring-sown white lupin will require (i) early seeding, (ii) narrow row spacing, and (iii) high seeding rates.