Development of yield in two grain-sorghum hybrids. I. Dry weight and carbon-14 studies

Abstract

Growth and development of two grain-sorghum hybrids (De Kalb E57 and Texas 610) were examined under glasshouse conditions by sequential harvesting and the use of I4C. The grain yield per plant of Texas 610 was higher than that of E57, with higher total biological yield and similar harvest indices. The contribution to grain weight at maturity, of carbon assimilated prior to anthesis, was about 10% for each hybrid. The leaves were the main source of this material. After anthesis, dry weight data indicated that temporary storage of assimilates before retranslocation to the grain was of greater importance in Texas 610 than E57. This storage was largely in the leaves (including sheaths), upper internodes, and roots. A high grain-growth rate was maintained for longer by Texas 610 than by E57. Total dry weight production after anthesis in both hybrids was, at all stages examined, more than sufficient to maintain grain growth.