Pre-flowering Growth and Development of the Inflorescences of Maize

Abstract

The accumulation and partitioning of dry matter and nitrogen were examined in the developing tassel and two uppermost ear shoots of field-grown maize under varying levels of applied nitrogen and times of sowing. Accumulation of dry matter and nitrogen within an axillary branch always favoured the ear over the husk and shank. Dry matter and nitrogen accumulated faster in the first ear than in the tassel or second ear and the partitioning between inflorescences of dry matter and nitrogen was not affected by treatment. The relative rate of growth, RGR(dry matter), of the first and second ear shoots increased by up to 42% at high levels of applied nitrogen and with early sowing. In contrast, the relative rate of accumulation of nitrogen (RNAR) was not sensitive to N supply, although it was reduced, on average, by 22% at the late time of sowing. We conclude that accumulation, but not partitioning, of dry matter and nitrogen between developing inflorescences of maize are altered by nitrogen application, time of sowing, and position of the inflorescence on the stem.