Understanding physiological processes associated with yield-trait relationships in modern wheat varieties

New insights into changes in physiological processes associated with genetic gains in yield potential are essential for improved understanding of yield-limiting factors. Our field study was conducted at two sites with three N levels and 15 modern wheat (Triticum aestivum L.) varieties. The goal was to evaluate yield components, time courses of dry matter production, and N accumulation among different yield categories, and to determine physiological processes associated with yield-trait relationships. Close correlations were observed between yield and dry matter production after the stem elongation stage, particularly post-anthesis. Similar close correlations were observed between grain yield and N accumulation over the whole growing season, except for the re-greening stage. No positive correlation was found between yield and harvest index. Differences in dry matter production among different yield categories began at anthesis; differences in N accumulation emerged even earlier. We conclude that consistent increases in dry matter production (especially post-anthesis) and N accumulation are crucial for further improvements in wheat yield-trait relationships. (C) 2011 Published by Elsevier B.V.