Effects of Environment and Cutting on the Regrowth of a Sorghum‐Sudangrass Hybrid¹

Abstract

Dry matter production curves of the initial growth and regrowth after 1, 2, 3, or 4 cuttings of a sorghum‐sudangrass hybrid cultivar (Sudax SX‐11) were constructed for two planting dates. Growth rates were measured by harvesting at weekly intervals. Plants of the May seeding receiving no uniform cut or cut once, and plants of the seeding made 6 weeks later and not cut, produced up to 18,000 kg/ha dry matter. Plants of the May seeding previously cut 4 times, and plants of the later seeding cut 2 or 3 times, subsequently produced less than 4,000 kg/ha dry matter. Plants of the May seeding cut 2 or 3 times, and plants of the later seeding cut once, produced yields intermediate between these two extremes. Changes in height of apical meristem were related closely to rates of dry matter accumulation in many of the treatments. The seasonal distribution of dry matter production was altered by variations in planting date and cutting management. Environmental effects and cutting management both influenced dry matter production.