Fescues with large roots are drought tolerant.
Torbert H.A. | Edwards J.H. | Pedersen J.F.
Consideration of root/soil interactions is essential in adapting tall fescue (Festuca arundinacea Schreb.) to soil and climatic conditions of the Coastal Plain region of the southeast. Sandy soils of the region are very susceptible to the formation of hardpans. These compacted layers often restrict plant root development to the plow layer (0 to 6 in.) and prevent plant roots from reaching available moisture and nutrients in the subsoil horizons. Plants grown under these conditions are shallow rooted and will be subjected to water stress up to 50% of the time during the growing season. Although implements are available to penetrate the hardpan, they have high energy requirements and provide temporary remedies. The limitation of root growth due to compaction layers has been cited as a causal factor of drought stress and resulting stand decline of tall fescue in the southeast. Research was initiated to determine the differences in soil water extraction of four fescue lines with different root characteristics and "Kentucky 31" (KY-31) fescue used as a check. The fescues were grown on a sandy loam Coastal Plain soil with a known compacted zone at a depth of 0.4 to 0.6 m (16 to 24 in.). Two fescue lines with large diameter roots (LDR) in the range of 0.92 to 1.03 microm and xylem diameters of 0.16 to 0.19 micrometer penetrated the hardpan and extracted soil water to a depth of 48 in. In two fescue lines with small diameter roots (SDR) less than 0.9 micrometer soil water extraction was restricted to the soil volume above 0.6 m. The increase in soil water removed from depths greater than 0.6 m was reflected in a 40% increase in dry matter yield for the LDR lines as compared to the SDR fescue lines. The LDR fescue lines offer genetic germplasm to be incorporated into a breeding program to improve drought tolerance of fescue in the southeast.
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