Effects of interaction between nitrogen and potassium on the growth and yield of cassava

Abstract

Nitrogen and potassium are necessary nutrients for cassava and are generally deficient in soil, particularly nitrogen. High nitrogen fertilizer applications may induce greater a potassium requirement. The results showed that increasing nitrogen rates significantly increased plant height, SPAD value of the upper and lower leaf, the fresh and dry weight of leaf blade, stem+petiole, tuber and total weight. Increasing potassium rates was decreased the SPAD value of lower leaves. Nitrogen uptake in OSC and tuber was significantly affected by interaction between N and K, but N uptake in the leaf blade and the total N uptake were affected by increasing N rates. Potassium uptake in tuber and total K uptake were significantly affected by interaction between N and K but K uptake in stem+petiole and OSC affected by increasing K rates. Furthermore, the total uptake of N and K gave a high positive correlation with the fresh and dry weight of all plant parts except OSC. The correlation coefficient between uptake N and K in the leaf blade, stem+petiole, OSC, and tuber were 0.85**, 0.83**, 0.35* and 0.87**, respectively.