Studies on CO2 Uptake and CO2 Evolution in Each Part of Crop Plants : 1. Photosynthetic rate of corn tassels, sorghum ears and their leaf sheaths

[摘要] It is well known that corn and sorghum have high ability in dry matter production, and also have high activity in photosynthesis of leaves. This study has been made to elucidate the photosynthetic rate of corn tassels, sorghum ears and their leaf sheaths. The photosynthetic rate of the three organs was measured with an air flow method using the assimilation chember as shown in figure 1 for potted corn and sorghum plants. 1. The leaf sheaths and green stems of corn plants indicated the slight activity of net photosynthesis as 1∼2mgCO/dm2/hr in its maximum rate. On the other hand, sorghum leaf sheaths and green stems showed respectively a higher activity than that of corn, 18 and 10mg CO2/dm2/hr at 60 Klux of light intensity. 2. The corn tassels and the sorghum ears had a low activity of photosynthesis, and showed a tendency which immediately sloped down several days after the heading. Both the corn tassels and sorghum ears could be classified as the non-photosynthetic organs in the growth analysis study. The order of maximum rate of the net photosynthesis in each organ of the sorghum plant was as follows: leaf sheaths, stems, ears. Generally, the photosynthetic rate of observed organs in sorghum plants showed higher rates than those of corn plants. 3. It is considered that the sorghum leaf sheaths and green stems had contributed to dry matter production with their net photosynthetic activity. The green parts of both, the leaf sheaths and the stems in sorghum plants, should be classified as photosynthetic organs owing to their activity of 20mgCO2/dm2/hr under an illumianted condition.

[学科分类] 农业科学（综合）