The sources of assimilate for grain development in tall and short sorghum

Abstract

SUMMARYThe dry weight contributed to the grain yield of sorghum by different parts of the plant was measured by removing laminae and by shading the head. A Nigerian tall variety formed more dry weight after heading and had a larger leaf area duration than a short-season, hybrid sorghum, but its grain yield was smaller. Laminae contributed more than 80% of the dry weight formed after heading in the Nigerian sorghum but less than half of this went into the grain. The remainder went into the stem, mainly to replace respiratory losses, or accumulated in the rachis and branches of the head. Top, middle and bottom groups of laminae contributed 42, 22 and 12% respectively to the dry weight of the grain; the remaining 24% was contributed by the sheaths. In the short-season hybrid sorghum over 70% of the dry matter formed after heading was stored in the grain. Only about half of this came from the laminae; assimilation in the head and in the sheaths contributed about equally to the remainder.