Effects of sowing time and nitrogen on the grain yield and quality of four wheat cultivars grown in North Otago

Abstract

Abstract The effects of sowing time and nitrogen fertiliser on the grain yield and grain quality of ‘Aotea’, ‘Karamu’, ‘Kopara’, and ‘Takahe’ wheat were examined in six dryland experiments conducted in sub-humid regions of North Otago. Grain yield of all cultivars was reduced by 0.5–1.5 t/ha when sowing was delayed from early winter to early spring. Positive yield responses to nitrogen, applied in spring at the start of tillering, occurred with winter rather than spring sowings. ‘Aotea’ yielded less than the more recently released cultivars, but no differential cultivar responses to the experimental treatments were recorded. Sowing time and nitrogen yield responses occurred principally through changes in ear number. Plasticity in ear size (grain number and individual grain weight) was most evident in ‘Karamu’. ‘Aotea’ and ‘Takahe’ gave the highest flour extraction, but milling quality was little affected by sowing time or nitrogen fertiliser. Sensitivity of baking quality to sowing time was evident only in ‘Karamu’, and all cultivars improved with nitrogen applications for both sowing times. Work input for dough mixing was lowest for ‘Karamu’ and increased with spring sowing and nitrogen applications. Grain quality was most closely, but negatively, correlated with grain number per ear.