Abstract
AimsDeep-rooted agricultural crops can potentially utilize deep soil moisture to reduce periods where growth is water limited. Chicory (Cichorium intybus L.) is a deep-rooted species, but the benefits of deep roots to water uptake has not been studied. The aim of this study was to investigate the value of deep roots (>2 m) under topsoil water limitation.MethodsChicory grown in 4 m deep soil-filled rhizotrons was exposed to either topsoil drought or resource competition from the shallow-rooted species ryegrass (Lolium perenne L.) and black medic (Medicago lupulina L.). The effect on deep water uptake was assessed using non-destructive measurements of roots, soil water and tracers.ResultsWater uptake occurred below 1.7 m depth in 2016, and below 2.3 m depth in 2017 and contributed significantly to chicory water use. However, neither surface soil drying nor intercropping increased deep water uptake to relieve water deficit in the shoots.ConclusionChicory benefits from deep-roots during drought events, as it acceses deep soil moisture unavailable to more shallow rooted species, yet deep water uptake was unable to compensate for the reduced topsoil water uptake due to soil drying or crop competition.
Highlights
Minimizing water limitation during growth of agricultural crops is crucial to achieve full yield potential
Crop yield losses vary according to the timing and severity of water limitations, but even short-term drought can be a major cause of yield losses (Zipper et al 2016)
Plants grew well in both years, and as hypothesized, roots were observed below 3 m depth by the end of the growing season
Summary
Minimizing water limitation during growth of agricultural crops is crucial to achieve full yield potential. Crop yield losses vary according to the timing and severity of water limitations, but even short-term drought can be a major cause of yield losses (Zipper et al 2016). In areas where precipitation is sufficient to rewet the soil profile during a wet season, more shallow-rooted crops still experience water limitation during the growing season, as they do not have access to the water stored deeper in the profile. The potential influence of deep roots on water uptake has been highlighted numerous times (e.g. Canadell et al 1996; Lynch and Wojciechowski 2015), yet information about the contribution of deep roots to water uptake remains scarce. Deep root growth under field conditions has been suggested to be restricted by high soil strength, and unfavourable conditions such as e.g
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