抄録
The images of whole root system with regard to the growth direction of individual primary roots and their relationships to yield were examined using the improved cylinder sampling method. There was a proportional increase in the percentage of horizontally-growing primary roots with increase in yield up to about 500 g/m2. However, with further increase in yield, the proportion of vertically-growing primary roots and the diameter of primary roots became larger. From above-mentioned results, it is suggested that the vertically-growing primary roots with large diameter are important for higher yield.
