Yield, chemical composition, growth and maturity of ‘Williams’ banana fruit in relation to supply of potassium, magnesium and manganese

Abstract

In New South Wales, banana plantations are subject to shortages of K, Mg and possibly high Mn. We investigated the effects of a low supply of K and Mg and high Mn on ‘Williams’ banana grown in drainage lysimeters over 3 crop cycles. Low K supply reduced yield by 73%, low Mg reduced it by 17% and high Mn had no effect. The bunch-weight component, mean finger weight, was reduced most (57 and 13% by low K and Mg, respectively) and the fruit number per hand was reduced least (16 and 8%, respectively). Fruit growth was exponential, and the relative fruit growth rate was influenced by K supply and seasonal conditions. High Mn supply decreased fruit maturity (greenlife) by 23%. Low K supply increased greenlife 79%, but only in relation to its effect on fruit size. The concentrations of K and Mg in the fruit dry matter were largely independent of the concentration in the solution around the roots. Mn concentration in fruit dry matter was directly proportional to Mn supply. The concentration of Ca in fruit dry matter showed a significant ( P = 0.01) positive association with greenlife over all treatments.