The influence of potassium fertilizer application on tuber yield and mineral element content of potato petioles during the growing season

Potassium was applied at rates equivalent to 0, 135, and 250 pounds per acre (0, 151, 180 kg K/ha) to study the effect of soil applied K on tuber yields and concentration of mineral elements in the petioles of potato plants during growth both measured at 14 day intervals. Petioles were analyzed for N, P, K, Ca, Fe, Mg, Zn, Cu, Al, Mn, and B. Seasonal trends in petiolar K content were highly correlated with tuber bulking regardless of rate of K application. Increasing K application rates generally increased petiolar levels of K and Zn (early in the season) and decreased the levels of N, Mg, Ca, Zn (late in the season), Al, Fe, Cu, and B in the petioles. Concentrations of P and Mn were unaffected by K applications. Seasonal trends in the mineral element content of petioles were not influenced by K. Results indicate that a prediction model for tuber yield based upon trends in the K content of petioles is valid under differing soil levels of K.