Root water uptake and profile soil water as affected by vertical root distribution

Abstract

Water uptake by plant roots is a main process controlling water balance in field profiles and vital for agro-ecosystem management. Based on the sap flow measurements for maize plants (Zea mays L.) in a field under natural wet-and dry-soil conditions, we studied the effect of vertical root distribution on root water uptake and the resulted changes of profile soil water. The observations indicate that depth of the most densely rooted soil layer was more important than the maximum rooting depth for increasing the ability of plants to cope with the shortage of water. Occurrence of the most densely rooted layer at or below 30-cm soil depth was very conducive to maintaining plant water supply under the drysoil conditions. In the soil layers colonized most densely by roots, daytime effective soil water saturation (S e ) always dropped dramatically due to the high-efficient local water depletion. Restriction of the rooting depth markedly increased the difference of S e between the individual soil layers particularly under the dry-soil conditions due likely to the physical non-equilibrium of water flow between the layers. This study highlights the importance of root distribution and pattern in regulating soil water use and thereby improving endurance of plants to seasonal droughts for sustainable agricultural productivity.

Genotypic variation in soil water use and root distribution and their implications for drought tolerance in chickpea

“…Under DS, at any specific growth stage, some specific soil depth(s) facilitated maximum water uptake and this soil zone was found to descend constantly across growing duration (Yu et al 2007;Wang et al 2012;Cutforth et al 2013;Kashiwagi et al 2015). When the integrated water uptake at the last sampling was considered, the maximum soil water uptake under DS was from 45-60 cm soil depth while under OI it was either 0-30 cm as seen in the first year or from 30 to 45 cm as in second year.…”

“…In summary, when water is not limited plants prefer to utilise water more from surface soil layers (Ludlow and Muchow 1990). Plants are forced to mine deeper soil layers only when water is limited (Serraj et al 2004;Pinheiro et al 2005;Yu et al 2007;Manschadi et al 2010;Hammer et al 2009Hammer et al , 2010Wasson et al 2012;Comas et al 2013;Krishnamurthy et al 2013;Lynch 2013;Steele et al 2013). For example, in modelling exercises of soil water utilisation the root system had been considered to extract 40% of the total transpiration from the top quarter of root zone, even if the top layer is desiccated by evapotranspiration (Molz and Remson 1970) that was also confirmed to occur in chickpea (Krishnamurthy et al 1999(Krishnamurthy et al , 2010Serraj et al 2004;Kashiwagi et al 2015).…”

Using lagged dependence to identify (de)coupled surface and subsurface soil moisture values

“…2256 C. D. U. Carranza et al: Using lagged dependence to identify (de)coupled soil moisture values moisture distribution by root water uptake (Yu et al, 2007) and by changing soil structure (Angers and Caron, 1998).…”

Benchmarking test of empirical root water uptake models

“…The study and modelling of the involved interactions is motivated by the importance of transpiration for global climate and crop growth (Chahine, 1992) as well as by the role of root water uptake (RWU) in soil water distribution (Yu et al, 2007). The common modelling approach introduced by Gardner (1960), referred to as microscopic or mesoscopic (Raats, 2007), is not readily applicable to practical problems due to the difficulty in describing the complex geometrical and operational function of the root system and its complex interactions with soil (Passioura, 1988).…”