Effects of plant spacing on yield, size and kernel fill of sweetcorn

Abstract

The effect of plant density (1.1-20 plants/ m2) on the yield of cobs, weight per cob and per cent kernel fill was determined for 3 types of sweetcorn (Zea mays), viz. sugary, sugary enhanced and shrunken, in 1984-85 and 1985-86 at Oakbank in South Australia. Response curves were fitted by inverse linear, inverse quadratic or quadratic equations. Of the shrunken (super sweet) cultivars Honey Sweet yielded highest, with 30.2 and 28.3 t/ha at densities of 14.0 and 11.2 plants/m2, which was marginally below (P>0.05) the yield of sugary (traditional), Golden Early Improved (31-6 t/ha at 7.5 plants/m2). Maximum mean weights of cobs of Honey Sweet in 1984-85 and 1985-86 were 0.40 and 0.38 kg at densities of 7.1 and 6.6 plants/m2. Most other cultivars produced the largest cob weight at 1.1 plants/m2. Sugar Sweet yielded less than Honey Sweet, but filled a higher percentage of the cob with kernels at all densities. There was 95.1% kernel fill at optimum density of 7.0 plants/m2 for Sugar Sweet compared with 90.6% for Honey Sweet for which the optimum density was not clearly defined. In the other cultivars, kernel fill declined as density increased from 1.1 to 20. Highest gross margins for Honey Sweet were obtained at 8-12 plants/m2 but, above 8 plants/m2, kernel fill and cob size rapidly decreased.