Long-term nutrient absorption rates and competition between ions in banana in relation to supply of K, Mg and Mn

Abstract

To provide data on the diagnosis and correction of deficiencies of K, Mg and high Mn experienced in the banana plantations of New South Wales, a sand culture experiment, in 1 m3 containers, was conducted using ‘Williams’ banana. Here we report the effects of K, Mg and Mn treatments on plant and root uptake rates of N, P, K, Ca, Mg, Na, Mn, Cu and Zn and the interaction beween K, Mg and Mn. Increased K supply increased the plant uptake rate of K and P whereas N, Ca, Mg and Cu were decreased. There was no large overall effect of Mg supply on the uptake of elements other than Cu. Within the K series the proportion of roots decreased as K supply increased and the root uptake rate of K, Mg, Mn and Cu was proportional to the concentration in the external medium. For other elements uptake was influenced more by demand within the plant. High Mn supply reduced the uptake of Ca, Mg and Zn but had little effect on the other elements. Values of root uptake rate were only 10% of those reported on other crops, but our data apply to a long time period (~ 1300 days). K and Mn non-competitively inhibited Mg uptake. The K/(Ca + Mg) ratio of the lamina was unable to distinguish between K and Mg deficiency as it did not show an optimum relationship with yield.