Winter Wheat Grain Yield Responses to Soil Oxygen Diffusion Rates 1

Aeration status of a Southern Piedmont Cecil sandy loam soil (Typic hapludult) during the reproductive phase of winter wheat ( Triticum aestivum L. cv. Stacy) growth affects grain yields. This study characterized gaseous soil oxygen diffusion rates (ODR) and concentration during the reproductive phase of winter wheat growth in 1983 and 1984. Soil oxygen diffusion rates at 0.10, 0.20, 0.30 and 0.45 m depths; and O2 concentrations at 0.20 and 0.50 m depths were measured in drained and undrained plots planted to wheat. The ODR in 1983 were all less than 33 µg −2 S −1 , and between Days 115 and 152 of 1984 the 0.10, 0.20, and 0.30 m depths were approximately 50 µg m −2 S −1 . Soil O 2 concentration was not affected by drainage treatment in 1983, and in 1984 was lower at the 0.50 m depth in the drained plots. Air temperatures were predominately higher after Day 100 (flag leaf just visible) in 1983 than 1984. Poor rainfall distribution in May and June 1984 made them dry months. Grain yields averaged 240 and 393 g m −2 in 1983 and 1984, respectively; the 2‐yr averages for drained and undrained plots were 323 and 309 g m −2 . Grain yields were significantly different for years but not for drainage treatment. Selecting soft red winter wheat cultivars that adapt to low ODR (wet soils) by development of aerenchyma tissue, which arises by cell separation (schzogenously) or by partial breakdown of the cortex (lysigenously), giving rise to continuous gas‐filled lacunae may be the only practical solution to obtaining consistently high soft red winter wheat yields in waterlogged Southern Piedmont soils.