Zhang X X, Whalley P A, Ashton R W, Evans J, Hawkesford M J, Griffiths S, Huang Z D, Zhou H, Mooney S J, Whalley W R
Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ UK.
University of Oxford, Radcliffe Observatory, Andrew Wiles Building, Woodstock Rd, Oxford, OX2 6GG UK.
Plant Soil. 2020;451(1):345-356. doi: 10.1007/s11104-020-04530-3. Epub 2020 May 1.
We aim to quantify the variation in root distribution in a set of 35 experimental wheat lines. We also compared the effect of variation in hydraulic properties of the rhizosphere on water uptake by roots.
We measured the root length density and soil drying in 35 wheat lines in a field experiment. A 3D numerical model was used to predict soil drying profiles with the different root length distributions and compared with measured soil drying. The model was used to test different scenarios of the hydraulic properties of the rhizosphere.
We showed that wheat lines with no detectable differences in root length density can induce soil drying profiles with statistically significant differences. Our data confirmed that a root length density of at least 1 cm/cm is needed to drain all the available water in soil. In surface layers where the root length density was far greater than 1 cm/cm water uptake was independent of rooting density due to competition for water. However, in deeper layers where root length density was less than 1 cm/cm, water uptake by roots was proportional to root density.
In a set of wheat lines with no detectable differences in the root length density we found significant differences in water uptake. This may be because small differences in root density at depth can result in larger differences in water uptake or that the hydraulic properties of the rhizosphere can greatly affect water uptake.
我们旨在量化35个实验小麦品系根系分布的差异。我们还比较了根际水力特性变化对根系水分吸收的影响。
在田间试验中，我们测量了35个小麦品系的根长密度和土壤干燥情况。使用三维数值模型预测不同根长分布下的土壤干燥剖面，并与实测土壤干燥情况进行比较。该模型用于测试根际水力特性的不同情景。
我们发现，根长密度无明显差异的小麦品系可导致具有统计学显著差异的土壤干燥剖面。我们的数据证实，土壤中所有可用水分的排出需要至少1厘米/厘米的根长密度。在根长密度远大于1厘米/厘米的表层，由于水分竞争，水分吸收与生根密度无关。然而，在根长密度小于1厘米/厘米的深层，根系水分吸收与根密度成正比。
在一组根长密度无明显差异的小麦品系中，我们发现水分吸收存在显著差异。这可能是因为深层根密度的微小差异会导致水分吸收的较大差异，或者根际水力特性会极大地影响水分吸收。
