Plant Water Relationships of Spring Wheat as Influenced by Shelter and Soil Water

Field windbreaks have been planted primarily for soil erosion control; subsequently, research has shown that windbreaks have an effect on microclimate and on growth and yield of crops. Other research has shown that plant water relations respond to changes in microclimate. The present work was undertaken to determine the effect of microclimate changes induced by a slat-fence windbreak on the plant water relations of field-grown wheat (Triticum aestivum L.). Slat-fence barriers were used as windbreaks for studying effects of shelter-modified microclimte on plant water relations of ‘Waldron’ spring wheat, grown on Parshall fine sandy loam (Pachic Haploboroll), under irrigated and dryland soil water regimes. Data were collected on leaf water potential (Ψₗ), xylem water potential (Ψₓ), stomatal diffusion resistance (rₛ), canopy temperature (Tc), soil water potential (Ψₛ), soil water extraction, and grain yield. Plant water status of the wheat crop was strongly affected by shelter and soil water content. The treatment combination of shelter plus irrigation produced a higher Ψₗ and lower Tc and, overall, was the most beneficial treatment in creating a favorable plant water status. The dryland treatments were under considerable water stress from early heading to maturity. The presence of the shelter did not alleviate the water stress on the dryland-grown plants. Water-use efficiency was significantly higher for the irrigated-sheltered as compared with the irrigated-exposed treatments. Water-use efficiency of the dryland treatments was lower than the irrigated treatments, but the dryland treatments did not differ from each other. The results of our study indicated that windbreaks will be most beneficial to a wheat crop only if soil water is adequate for good crop growth throughout the growing season. Because soil water varies considerably from year to year in the northern Great Plains, crop responses to windbreaks can also be expected to vary considerably.