Growth Stages and Distribution of Dry Matter, N, P, and K in Winter Wheat

Stage of growth descriptions were developed for winter wheat (Triticum aestivum L.) which will apply to single plants or a community of plants. The growth stages are easily discernable and precise. Accumulations of dry matter, N, P, and K in leaves, culms, head, and grain were measured at each growth stage. Observations and plant samples were taken of fieldgrown winter wheat (cultivar ‘Centurk’) over the 3-year period of 1975-77. Plants were grown at the Univ. of Nebraska Agronomy Farm, Lincoln, on a Sharpsburg silty clay loam (Typic argiudoll). Plants for growth stage description and chemical analysis were randomly sampled from a field population and separated into leaves, culms, head, and grain as these plant parts developed. Growth stages are defined and illustrated. The 10 developmental stages are: O-Emergence, 1-Crown development and tillering, 2-Leaf sheath elongation, 3-Culm elongation (jointing), 4-Flag leaf emergence, 5-Peduncle elongation (heading), 6-Flowering (anthesis), 7-grain filling, 8-Stiff dough, 9-Hard dough (ripening), and 10-Maturity. Dry matter accumulation increased rapidly from stage 3 through stage 8. Translocation of dry matter from leaves to grain began at stage 6 and from culms and head to grain at stage 7. Nitrogen uptake was most rapid from stage 2 to stage 4 with 80% of the total accumulation occurring by stage 7. Over 70% of the total N uptake was translocated to the grain at maturity. Uptake of P and K was most rapid from stage 3 to stage 7. Seventy-five percent of P uptake was translocated to the grain at maturity but only 15% of K present in the plant was found in the grain at maturity. The stage descriptions provide a standard for researchers, extension workers, producers, students, and agribusiness personnel to accurately define and determine the growth stages of winter wheat. The dry matter accumulation and nutrient uptake data provides part of the information necessary in making correct management decisions.