The effect of nitrogen fertilizer and irrigation frequency on a semi-dwarf wheat in south-east Australia. 1. Growth and yield

Abstract

An experiment in south-eastern Australia in 1971 examined the semi-dwarf wheat WW15 when grown with two rates of nitrogen fertilizer (nil, 112 kg N ha-1) and under four irrigation regimes. The irrigation regimes comprised natural rainfall only (293 mm), and 2, 3 or 7 flood irrigations, scheduled according to cumulative pan evaporation. Nitrogen fertilizer had little effect, but grain yield increased from 4.3 t ha-1 with no irrigation to 8.1 t ha-1 with 7 irrigations. Each increase in irrigation frequency produced a significant (P < 0.01) increase in grain yield. A greater individual grain weight contributed most to the yield difference between nil and 2 irrigations. More spikes m-2 contributed most to the yield increase with higher irrigation frequencies. Irrigations also increased plant height, dry matter, leaf area and the proportion of fertile shoots.