Short-term changes in bunch weight were found to contribute to seasonal yield cycles in an oil palm density trial on a peat soil in Perak, West Malaysia. Unusually, the cycle in bunch weight was in phase with that in bunch number. The results of bunch analyses carried out over a 10-year period were examined to identify whether cycles also occurred in bunch components and to examine the effects on oil and kernel yields. The analysis showed that total fruit weight per bunch fluctuated more than the weight of the bunch frame, while within the fruit, the mesocarp showed a greater variation in weight per bunch than the nut. However, while the seasonal changes in fruit-to-bunch (F/B) on a mean monthly basis over years were significant, there were no comparable significant changes in the other bunch component ratios.

There was some evidence based on changes in single fruit weight and fruit number that the changes in F/B might be due to variation in pollination efficiency.

The variation in mesocarp weight per bunch was attributable to variation in both the oil and water contents with little change in the fibre. Similarly, within the nut, the larger shell component tended to vary more than the kernel.

The contribution of bunch weight variation to the variation in total yield and its relationship to bunch number are discussed.