Abstract
Effects of various cultural conditions, such as the maturing stage, harvesting season, soil and cultivar, on total sugar content, vitamin C content and β-amylase activity were investigated with the following results.
1. Radish roots at the early maturing stage showed a higher vitamin C content and β-amylase activity than those at the late maturing stage.
2. The fluctuation of total sugar content in root juice was positively correlated with the integrated solar radiation several days before harvesting in early summer, and negatively correlated with the integrated rainfall several days before harvesting in autumn.
3. Radish roots harvested during early summer were lower in total sugar content, but higher in β-amylase activity than those harvested during late autumn when compared on the basis of the same root weight.
4. Radish roots grown in alluvial soil had a slightly higher total sugar content, vitamin C content and β-amylase activity than those grown in ando soil.
5. Shade culture, mulching treatment by plastic film, and plant density showed little effect on total sugar content, vitamin C content and β-amylase activity.
6. There was a difference in β-amylase activity among the ten cultivars of the major seven genetic groups tested, but a little difference in vitamin C content and total sugar content.
