| Abstrakt: |
Growth of some plant species on some soils may results from their adaptation to soil-desiccation contraction forces, which constrict roots. This constriction was simulated by placing the roots of ‘Eureka,’ ‘Olaf,’ or ‘SD 2256’ spring wheat plants between rigidly held, 13-mm-OD plastic tubes that were inflated with air. If water transport is inhered, the effect or root constriction on plant growth should parallel growth at low, in comparison with high, soil water. This aspect ws studied in the greenhouse and found to be correct in some cases. In others, stresses from high evapotranspiration probably masked the effect of the constricting force. Heading was accelerated in some Eureka plantings by a root constricting force of 0.6 MPa or by allowing the soil to dry between waterings. Olaf produced more spikes but less straw and tended to produce less grain than SD 2256. Straw and grain weights tended to be larger, but not significantly larger, for plants treated either with pressure or with high soil water. Fewer main roots, seminal plus nodal, were produced with root constriction, but the grain and straw yields were not reduced. |
