ORCID Profile
0000-0002-0180-7223
Current Organisation
University of the West of Scotland
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Publisher: Wiley
Date: 2018
Abstract: We hypothesized that plant exudates gel soil particles and on drying enhance water repellency. This has been carried out using rhizosphere‐scale mechanical and hydraulic measurements. Plant exudates enhanced soil hardness and modulus of elasticity as chia seed maize root barley root. Plant exudates caused measureable decreases in soil wetting rates through water repellency. Using rhizosphere‐scale physical measurements, we tested the hypothesis that plant exudates gel together soil particles and, on drying, enhance soil water repellency. Barley ( Hordeum vulgare L. cv. Optic) and maize ( Zea mays L. cv. Freya) root exudates were compared with chia ( Salvia hispanica L.) seed exudate, a commonly used root exudate analog. Sandy loam and clay loam soils were treated with root exudates at 0.46 and 4.6 mg exudate g −1 dry soil and chia seed exudate at 0.046, 0.46, 0.92, 2.3 and 4.6 mg exudate g −1 dry soil. Soil hardness and modulus of elasticity were measured at −10 kPa matric potential using a 3‐mm‐diameter spherical indenter. The water sorptivity and repellency index of air‐dry soil were measured using a miniaturized infiltrometer device with a 1‐mm tip radius. Soil hardness increased by 28% for barley root exudate, 62% for maize root exudate, and 86% for chia seed exudate at 4.6 mg g −1 concentration in the sandy loam soil. For the clay loam soil, root exudates did not affect soil hardness, whereas chia seed exudate increased soil hardness by 48% at 4.6 mg g −1 concentration. Soil water repellency increased by 48% for chia seed exudate and 23% for maize root exudate but not for barley root exudate at 4.6 mg g −1 concentration in the sandy loam soil. For the clay loam soil, chia seed exudate increased water repellency by 45%, whereas root exudates did not affect water repellency at 4.6 mg g −1 concentration. Water sorptivity and repellency were both correlated with hardness, presumably due to the combined influence of exudates on the hydrological and mechanical properties of the soils.
Publisher: Wiley
Date: 31-07-2017
DOI: 10.1111/NPH.14705
Abstract: In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root–soil interface during the early stage of crop establishment. This was achieved by use of high‐resolution ( c . 5 μm) synchrotron radiation computed tomography ( SRCT ) to visualise both the structure of root hairs and the soil pore structure in plant–soil microcosms. Two contrasting genotypes of barley ( Hordeum vulgare ), with and without root hairs, were grown for 8 d in microcosms packed with sandy loam soil at 1.2 g cm −3 dry bulk density. Root hairs were visualised within air‐filled pore spaces, but not in the fine‐textured soil regions. We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space ( 5 μm) in the rhizosphere, as compared with the no‐hair mutants. Both genotypes showed decreasing pore space between 0.8 and 0.1 mm from the root surface. Interestingly the root‐hair‐bearing genotype had a significantly greater soil pore volume‐fraction at the root–soil interface. Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image‐based modelling.
Publisher: Wiley
Date: 27-10-2017
DOI: 10.1111/EJSS.12487
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Muhammad Naveed.