Aerial Parts of Hard Red Spring Wheat. I. Dry Matter Distribution by Plant Development Stage 1

Information is lacking on the proportionate mass distribution of dry matter among aerial components of spring wheat ( Triticum aestivum L.) over its life cycle at recognized plant development stages. Benefits of such an assessment would accrue to segments of the agricultural industry and modelers/forecasters of crop development and yield. Measurements of aerial components were made weekly from the three‐leaf to kernel‐hard stage of three spring wheat cultivars grown on Williams loam (fine‐loamy, mixed Typic Argiborolls) with three fertilizer N and three water levels in 1981 and 1982. Relations were determined of total aerial dry mass percent in leaves, stems, and spikes, of tillers per plant, fresh and dry leaf mass, and leaf area index (LAI) to the Haun scale expanded to include grain filling, and, as well, fresh and dry leaf mass to LAI. Development stage accounted for 92,96,85, and 79% of the change in total aerial dry mass and in percent of aerial dry mass in leaves, stems, and spikes, respectively, and 52, 85, 59, and 59% of tillers per plant, LAI, dry leaf mass, and fresh leaf mass, respectively. About 50% of aerial dry mass at flag leaf was distributed in each of leaves and stems, while maximum tiller number occurred one Haun stage earlier, and maximum LAI at boot stage. Water and N variables altered the magnitude of mass change, but did not cause a shift in development stage when maximums occurred. Through flag‐leaf‐extension stage, LAI changed one unit for each increase of 37 and 237 g m −2 of dry and fresh leaf mass, respectively.