Carbon 14 Translocation in Three Warm-Season Grasses as Affected by Stage of Development

Abstract

Radioactive carbon dioxide was utilized to trace carbohydrate translocation in blue grama, sideoats grama, and switchgrass. Tagged tillers retained 77% of their fixed carbon following a 24-hour translocation period. The roots were the strongest sink of assimilate, receiving 76.2% of the total 14 C translocated. The pre-elongated and elongated tiller fractions received 16.3% and 7.5% of the 14 C translocated, respectively. Major differences among the grasses became evident upon examination of relative total activity (RTA) ratios in elongated/pre-elongated tillers and root/shoot fractions. Switchgrass produced many more elongated tillers and had the highest elongated/pre-elongated RTA ratio. Blue grama had the greatest weight of pre-elongated tillers, a strong above-ground sink, and therefore had the lowest root/shoot RTA ratio. Sideoats grama had RTA ratios similar to those of blue grama.