Relationship of first hollow stem and heading in winter wheat

The majority of wheat (Triticum aestivum L.) in the southern Great Plains is produced as a dual-purpose crop enterprise. Profitability of the system is highly dependent on removal of cattle (Bos taurus L.) from wheat pastures at the first-hollow-stem stage of growth. A previous survey implied that earliness of first hollow stem and earliness of heading are independent traits, which would allow a grower to select a cultivar with late first hollow stem without sacrificing early maturity. We evaluated first hollow stem and heading records for 52 hard winter wheat lines (49 commercially available winter wheat cultivars and three advanced experimental lines) during a 7-yr period at Stillwater, OK Our analysis shows a positive, linear relationship between the occurrence of first hollow stem and heading in wheat when these phenological events were expressed as a function of cumulative thermal units after 1 January. When expressed in terms of calen dar date, however, intervals between the earliest and latest cultivars for the first-hollow-stern stage were much greater than those for heading date. Overall, our analysis indicates that among commercially available cultivars and advanced experimental lines, choosing a cultivar with later occurrence of first hollow stem will also result in later heading in the same given environment.