Dry matter and nitrogen partitioning to the grain of winter wheat (Triticum aestivum ) cultivars grown on Broadbalk since 1843

The partitioning of dry matter and nitrogen to the grain of different winter wheat varieties has been studied using results for crops grown on the Section One (Continuous Wheat) of the Broadbalk Experiment since 1843. When averaged over all years during which they were grown, all varieties showed a linear relationship between grain dry matter and total crop dry matter, irrespective of the yield, or the nutrient treatment applied. The slope of this line is harvest index and was significantly greater for shorterstrawed varieties grown since 1969, compared with long-strawed varieties grown earlier. There were similar linear relationships between grain nitrogen and total crop nikogen. Greater proportions of nitrogen than dry matter were partitioned to the grain in all varieties but shorter-strawed varieties partitioned more of their nitrogen to the grain than did longstrawed varieties. Both harvest index and nitrogen harvest index have increased in parallel as new varieties, particularly shorter-strawed varieties, have been introduced.