Yacon (Polymnia sonchifolia POEPP. et ENDL or P. edulis WEDD), an indigenous Andean cultivated food plant, was imported as a new root vegetable from New Zealand in 1985. The cultivaton was already carried on a few advanced farmers. But the character and the planting system of Yacon are almost not known in Japan.
The planting densities, one of the basic problem to Yacon cultivation, were investigated.
Seed tubers were planted spacing of 30cm between the plants and 70cm between the rows (dense planting), spacing of 70cm between the plants and 70cm between the rows (sparse planting), and spacing of 50cm between the plants and 70cm between the rows (control).
Results of the investigation were obtained as follows:
1. Growth of the main stem of Yacon was grown well from July to the middle of October.
2. Growth of the main stem at the dense planting Yacon was slightly succulent grown more than any other growth at the planting density.
3. The fresh and the dry weight of the top at the sparse planting were heavier than any other weight at the planting density.
4. The weight and the number of tubers per a stump at the sparse planting were more than any other yield at the planting density.
5. The computation of the total number of the tubers per 10a of the control was more than any other yield at the planting density, but the number of tubers under 100g at the dense planting were more than any other yield at the planting density. And the number of tubers over 100g at the sparse planting were more than any other yield at the planting density.
6. The computation weight of the total and over 100g tubers per 10a of the sparse planting was heavier than any other weight at the planting density, but the weight under 100g at dense planting was more heavier than any other weight at the planting density.
7. Spacing of 70cm between the plants and 70cm between the rows was determined most useful planting density in this investigation.