THE INFLUENCE OF SOIL OXYGEN AVAILABILITY ON YIELD AND NUTRIENT-UPTAKE (N, P, K, CA, MG, NA) BY WINTER RYE (SECALE-CEREALE)

The influence of soil oxygen diffusion rate (ODR) on winter rye (Secale cereale cv Dankowskie Nowe) growth, yield, and mineral composition was studied in the greenhouse. A range of soil ODR values was created by manipulating soil water tension and soil bulk density. The soil bulk densities used during the experiment were: 1.20, 1.35 and 1.50 Mg m-3. The soil water tensions used were 15-80 kPa (control), 2-5 kPa and 0 kPa (2-5 mm of water ponded on the soil surface). The 2-5 and 0 kPa water tensions were applied for 15 days beginning at 3 growth stages (stress I at two-three leaves, stress II at shooting, stress III at heading). Yield at full maturity decreased to as little as 30-50% of the controls when ODR dropped below 20-mu-g m 2 s-1. When soil hypoxia occurred early (2-3 leaves, or shooting), straw weight decreased for ODR <20 -mu-g m-2 s-1 and root potassium content increased for ODR below 10-mu-g m-2 s-1. The uptake of all measured macroelements was decreased at low oxygen availability. Oxygen diffusion rates of >30-mu-g m-2 s-1 were needed for adequate nutrient uptake.