Ear Developmental Stage Used for Timing Supplemental Nitrogen Application to Spring Wheat

Abstract

Nitrogen fertilization at sowing is not always optimal or sufficient for stable yield and quality formation of wbeat (Triticum aestivum L.). Precise timing of supplementary N application for wheat requires detailed knowledge of the physiology of the reproductive phase. Our objective was to compare developmental stages of the wheat ear, for timing supplemental N application to ensure stable wheat yield and quality. The experiments were carried out at two locations in 1989 and 1990, with four spring wheat cultivars. Soil types were sandy loam (Mollie Cryoborolls). Foliar N (20 kg ha−1) as an aqueous solution of urea (144 g L−1) was applied at f our stages of ear development. A greenhouse experiment was designed to clarify the effect of N on the formation of spikelet and floret numbers in the apex during reproductive period. Maximum effect of supplementary N was achieved at the double‐ridge stage, and at the stage when the stigmatic branches of the carpel had formed. At these developmental stages, supplementary N increased the number of grains per ear and grains per square meter. Nitrogen added at pollination mainly increased the kernel weight and bread‐making quality (rated according to protein concentration in the flour, wet gluten content, Zeleny sedimentation value, farinograph water absorption, dough stability, and Panasonic loaf volume). Timing N application to apical development may provide a useful method for the producer to stabilize wheat grain yield and protein concentration.