Abstract
The carbon dioxide exchanges of the detached pod of rapeseed were measured in an assimilation chamber under controlled environments once in 12 days throughout the period of pod development. From the results presented in Figs. 1, 3, 4, 5 and 6, carbon content of the pod and the actual climatic data, the contribution to the total require-ments for the growth of pod was sought as to pod photosynthesis and translocation from other organs. The following results were obtained: 1. Apparent photosynthesis of the pod showed a value near to 10.5 mgCO2/dm2 surface area/h during 12-36 days after flowering, and then declined rapidly as the pod matured. The optimum temperature for the apparent photosynthesis of the pod was 20∼25°C during the whole period of pod development. 2. Dark respiration of the pod was high (6.3 mgCO2/g dry weight/h) at the early stage of pod development, and declined rapidly as the pod matured. Temperature coeffcient, 〓10, for the dark respiration of the pod was 2.2 for 10-30°C. 3. The dry weight of pericarp increased rapidly after flowering, and reached the maximum value at the earlier stage of pod development. On the other hand, the dry weight of seed increased gradually after flowering, and reached the maximum value at the later stage of pod development. Most of the dry matter needed for pod growth was translocated from other organs during the period of pericarp growth, and was provided by pod photosynthesis during seed development. 4. For the whole period of pod development, the contribution of gross photosynthesis by the pod and of translocation from other organs to total requirements were 70% and 30%, respectively. The proportion of respiration by the pod and of pod growth to total requirements were 39% and 61%, respectively.
