サツマイモの養液栽培に関する研究

抄録

A new technique for cultivating sweet potatoes (I pomoea batatas L.) in a solution culture in order to make root tuber formation in the air space of a culture box was developed. The effects of rockwool slab in the medium, and also the composition and supplying method of nutrient solution were examined to maximize root tuber yield. This technique was also applied to compare the yield differences among cultivers. Cultiver‘Kokei No. 14, ’‘Kotobuki’and‘Narutokintoki’were used in this experiment. The plastic culture box (W 400×D 700×H 320 mm) was separated into two parts, i.e., the solution layer which was set in the rockwool slab of 2 cm in thickness and the air space of about 30 cm.
Seedlings were provisionally planted in sand medium for about twenty days before trans-planting until the root length was elongated to 30-40 cm so that the root reached the solution layer when it was planted at the top of the culture box. Absorbing root was grown in the solution layer, and root tuber was tuberized in the air space. The results of the experiment are as follows.
1) From the experiment on the relation between root tuberization and medium composition, yield of root tuber was increased by 1.5 times when standard solution (Kasugai's solu-tion-B) were used in the rockwool slab compared to the case without the rockwool slab.
2) From the experiment on the relation between the root tuberization and the composition of the culture solution, it was found that root tuberization was improved and the yield was increased by 1.45 times when the concentration of NH₄N0₃ in Kasugai's solution-B was doubled for 30 days after transplanting, and subsequently, concentrations of KCl and KH₂PO₄ were doubled until the harvest.
3) Large yield, 1.350, 1.350, 1700 g/plant for‘Kokei No. 14, ’‘kotobuki’and ‘Naruto-kintoki’respectively, indicated that the solution culture is suitable for various cultivers of sweet potatoes.