Analysis of yield trends in two cultivar trials in Indonesia
1992
Gerritsma, W. | Soebagyo, F.X. (Bah Lias Res. Station, P.T.P.P. London Sumatra, Medah (Indonesia)) | Redshaw, M.J. (Harrison Fleming Advisory Services, London Sumatra, Medan (Indonesia))
Ten and a half years growth data from cultivar density trials in North Sumatra were studied to examine trends in TDMc (the carbohydrate incorporated into above ground dry matter), and its components VDMc (vegetative aboveground carbohydrate production) and Yc (carbohydrate equivalent for bunch yield). VDMc reached a maximum value at about 4 to 5 years after planting, and remained stable. Yc and TDMc reached a peak at about the same time that the leaf area index (LAI) approached its maximum, 6-7 years after planting. From this stage, light interception remained high and did not further change appreciably. After declining to a trough some 2-3 years later, both TDMc and Yc recovered to a plateau level. These observed trends are discussed in the light of results reported by other works. The trends in LAI, TDMc and VDMc did not satisfactorily explain the observed decline in yield. It is suggested that yield in this period is limited by the bunch sink as a result of a decreased sex ration following the yield peak. It is predicted that, following the canopy closure, photosynthetic production and yields should remain stable and that the optimum planting density for current economic yield does not change
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