PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Amorphophallus oncophyllus is widely cultivated in Indonesia to obtain starch and glucomannan content. The low productivity of the A. oncophyllus plant, which is only 6-12 tons ha⁻¹ of fresh tubers, may be attributed to cultivation techniques that are still not intensive and remain dependent on natural harvest. The use of fertiliser type and tuber size is very important to increase production, as well as being efficient with the planting material used. The aim of this research is to evaluate the effect of inorganic fertiliser types (urea fertiliser, ammonium sulfate fertiliser and NPK fertiliser) and tuber size (whole tubers weighing 100 g, large tuber weighing 200 g (cut into 2 pieces), tuber 300 g (cut into 3 pieces) and tuber 400 g (cut into 4 pieces) on the growth and glucomannan content of A. oncophyllus. The results showed that statistical analysis showed no interaction between fertiliser type and tuber size treatments. Fertiliser type has an effect on stem diameter at 8 weeks after planting (WAP). Seed tuber portions influenced only the parameters of tuber number, tuber weight, and tuber diameter at the end of the observation period. The whole tuber treatment product relatively larger stem diameter at 11 weeks after planting (WAP), tuber diameter, and tuber weight compared with the half-tuber portion treatment. Our findings indicate that the whole tuber (100 g) has a relatively significant influence on tuber growth and glucomannan yield, providing important insights for commercial cultivation strategies.