Soil textures rather than root hairs dominate water uptake and soil–plant hydraulics under drought

• DOI: 10.1093/plphys/kiab271
• Publication Date: 2021-06-10T19:13:19Z
• Authors: Gaochao Cai; Andrea Carminati; Mohanned Abdalla; Mutez Ali Ahmed
• Keywords: Hydraulics; Root hair; Plant Roots; Plant roots; Root (linguistics)

Abstract Although the role of root hairs (RHs) in nutrient uptake is well documented, their water and drought tolerance remains controversial. Maize (Zea mays) wild-type its hair-defective mutant (Mut; roothairless 3) were grown two contrasting soil textures (sand loam). We used a pressure chamber to measure relation between transpiration rate (E) leaf xylem potential (ψleaf_x) during drying. Our hypotheses were: (1) RHs extend root–soil contact reduce ψleaf_x decline at high E dry soils; (2) impact more pronounced sand; (3) Muts partly compensate for lacking by producing longer and/or thicker roots. The ψleaf_x(E) was linear wet conditions became nonlinear as soils dried. This nonlinearity occurred abruptly less negative matric potentials sand (ca. −10 kPa) than loam −100 kPa). At potentials, hydraulic conductance smaller both soils. Both genotypes exhibited 1.7 times roots loam, but 1.6 sand. No differences observed active length genotypes. In maize, had minor contribution soil–plant hydraulics putative that reported barley (Hordeum vulgare). These results suggest cannot be easily generalized across species affect response