Effects of the application ratio of potassium to nitrogen on top growth, tuber-formation and thickening of sweet potatoes grown on different types of soil

Abstract

Wooden frame experiments were conducted to study the effects of the application ratio of potassium to nitrogen on top growth, tuber-formation and-thickening of sweet potatoes. Four types of soil differing in their clay content were used. Two cuttings were planted in each frame.
1. According to the increase of the application ratio of potassium to nitrogen, top growth was gradually weaken throughout the growing period in every type of soil, and also the percentage of parts of young vines decreased.
2. Small application ratio of potassium to nitrogen was unfavourable to tuber-formation due to the vigorous vine growth during the period of tuber-formation, however, it was favourable to the increase of tuber yield, especially that of large tubers, as the vine growth was vigorous after tubers began to thicken.
3. As the application ratio of potassium to nitrogen increased, the percentage of dry matter content of tubers in every type of soil gradually decreased.