COMPOSITIONAL CHANGES IN DEVELOPING PODS AND SEEDS OF OILSEED RAPE (BRASSICA NAPUS L.) AS AFFECTED BY POD POSITION ON THE PLANT

Plants of rape (Brassica napus L. ’Erglu’) were grown under controlled greenhouse conditions. The growth and composition of pods (hulls) and seeds was followed from the day when flowering took place to maturity. Pod development could be divided into three stages. In the first stage hull growth was more rapid than seed growth. Nitrogen accumulation in hulls occurred at a maximum and seeds were characterized by a high protein content but a low oil content and a fatty acid composition similar to that of photosynthetic tissue. During the second phase dry matter of hulls began to decrease, nitrogen was exported and the rates of seed dry matter accumulation grew to a maximum. At the same time the protein content of seeds declined while oil content increased rapidly. The fatty acid composition had reached the final condition. In the third stage hulls continued to lose dry matter and the rates of seed dry matter accumulation decreased dramatically. Pod growth was affected by the location of the pod on the plant. The individual seed weight and the fatty acid compvsition at 16 days after flowering indicated an accelerated development of seeds from axillary branches. Pods from the main branch generally produced the largest amount of seed dry matter. From these results the ideal high-yielding rape plant was characterized.