Dryland Grain Sorghum Tillering: Clumps vs. Uniform Planting Geometries

摘要

When plant populations are reduced to 5.0 to 7.0 plants m−2to conserve soil water, sorghum (Sorghum bicolorL. Moench) forms two to three tillers, but these often produce little grain. We hypothesized that under dryland conditions manipulating planting geometry into clumps spaced 0.75 m apart might result in greater yield by reducing the number of tillers and increasing the percentage of tillers that produce panicles compared with uniform spacing. A field study was conducted during 2007 at Bushland, Texas, with two planting geometries (clump vs. equidistant), two irrigation methods (LEPA vs. LESA) at three irrigation levels (dryland, 50 mm and 100 mm). Clump plants had only 0.6 tillers compared with 1.5 tillers per plant for rows. Tillers accounted for 33% of stover for the equidistant plants but only 23% of the grain under dryland. Our results suggest that growing sorghum in clumps may be a useful strategy in semiarid dryland areas.