Quantifying seasonal transpiration of winter wheat with different root length distributions

In this study the effect of root growth and root length distribution on seasonal transpiration of winter wheat grown in a medium European soil under a temperate maritime climate was numerically investigated using an agro-hydrological model. Rooting depth of the crop was assumed to be proportional to the above-ground dry weight, and root length distribution was exponential from the soil surface with a shape parameter controlling root distribution. Results show that in dry growing years only about half potential transpiration was met, and more than 90% potential transpiration was supplied in wet growing years in both scenarios with a different shape parameter value. The seasonable transpiration with the shape parameter equal to 1 increased by 0.7% to 12.8% with the overall value of 5.6% over the simulation period of 21 years, compared with those from the shape parameter value of 3.