THE ALLOMETRIC MODEL TO ESTIMATE BIOMASS AND CARBON STOCK IN TOP GRAFTING YOUNG CACAO PLANTSAndi Besse Poleuleng, Herdhata Agusta, Sudirman Yahya, Ade Wachjar and Aiyen Tjoa
Allometric model for biomass estimation have been reported in cacao plant derived from seed, while there is still limited study specifically for those from vegetative multiplication technique. This study aimed to formulate a simple and non-destructive model for estimating biomass and carbon stock of top grafting young cacao plants. A total of 54 samples of 2-3 years old cacao plants originating from SUL1, SUL2, MCC02 and MCC01 clones were randomly selected from 18 locations in South Sulawesi and Central Sulawesi Province of Indonesia, from January to August 2019. Measurements were taken at the stem/branches/ twigs circumference as predictor variables and plant biomass/dry weight (g) as predicted variable. The result showed that among 23 developed models, there were 4 models selected as indicated by the high correlation coefficient (R2), namely model of stem circumference at 10 cm, 20 cm, 10+20 cm and 10+20+30 cm. Among four selected model, the chosen model was a stem circumference at 20 cm (SC20) model because it had the highest value of R2 and also involved only single predictor variable so that the model formed was simple and more efficient to apply. There was a close relationship (R2 = 0.914) between the results of carbon stock based on actual biomass and Sc20 model derived biomass.