Biology subjects

Rasmussen, C. R.

Publications and source records attributed to Rasmussen, C. R..

4 recordsLinked to original sources

bioRxiv2021

Dynamics of deep water and N uptake under varied N and water supply

AimsEnhanced nitrogen (N) and water uptake from deep soil layers may increase resource use efficiency whilst maintaining yield under stressed conditions. Winter oilseed rape (Brassica napus L.) can develop deep roots and access deep-stored resources such as N and water, while this potential has large uncertainties in variable environments. In this study, we aimed to evaluate the effects of reduced N and water supply on deep N and water uptake. MethodsOilseed rape plants grown in outdoor rhizotrons were supplied with 240 and 80 kg N ha-1 respectively in 2019 whereas a well-watered and a water-deficit treatment were established in 2020. To track deep water and N uptake, a mixture of 2H2O and Ca(15NO3)2 was injected into the soil column at 0.5 and 1.7 m depths. {delta}2H in transpiration water and {delta}15N in leaves were measured after injection. {delta}15N in biomass samples were also measured. ResultsDifferences in N or water supply had little effect on root growth. The low N treatment reduced water uptake throughout the soil profile, but caused a non-significant increment in 15N uptake efficiency at both 0.5 and 1.7 m. Water deficit in the upper soil layers led to compensatory deep water, while N uptake was not altered by soil water status. ConclusionOur findings demonstrate that for winter oilseed rape, high N application and water deficiency in shallow layers increases deep water uptake, and that the efficiency of deep N uptake is mainly sensitive to N supply rather than water supply.

plant biology↗

bioRxiv2020

Effects of kin recognition on root traits of wheat germplasm over 100 years of breeding

Plant root and shoot growth has been shown to depend on the relatedness of co-cultivated genotypes, implying the existence of kin recognition mechanisms mediated by root exudates. If confirmed, this has important implications for crop breeding. We present the first large-sale investigation of kin recognition in a crop germplasm collection comprising 30 North-European cultivars and landraces of spring wheat, spanning 100 years of breeding history. In a full diallel in vitro bioassay, we compared root growth of seedlings when growing in pure substrate, or in substrate previously occupied by a donor seedling from the same (KIN) or another (NONKIN) genotype. Seedlings growing in KIN or NONKIN substrate generally had longer but not more roots than seedlings growing in pure substrate. Responses were generally larger in longer roots, suggesting that root elongation was promoted throughout the growth period. Responses to KIN and NONKIN substrates were found to range from positive to negative, with root length responses to kin being increasingly positive with year of release. Seedlings growing in KIN substrate generally had shorter but not fewer roots than seedlings growing in NONKIN substrate. This kin recognition ranged from positive to negative across the specific donor-receiver combinations and did not change systematically with year of release of either genotype. Root traits in both KIN and NONKIN substrate were affected by both donor and receiver genotype, and these effects were generally larger than the effect of specific combinations. Genotypes showing higher levels of kin recognition also tended to invoke larger responses in other genotypes. Kin recognition was reduced in most cases by the addition of sodiumorthovanadate, a chemical inhibitor, supporting the hypothesis that kin responses were mediated by changes in the chemical constitution of the substrate. The identified patterns of kin recognition across the germplasm collection were complex, suggesting a multigenic background and shared breeding history of the genotypes. We conclude that kin response represents a potential target for crop breeding which can improve root foraging and competitive interactions.

plant biology↗

bioRxiv2019

The effect of drought and intercropping on chicory nutrient uptake from below 2 m studied in a multiple tracer setup

AimsWe tested if chicory acquires nutrients from soil layers down to 3.5 m depth and whether the deep nutrient uptake increases as a result of topsoil drought or topsoil resource competition. We also tested whether application of the trace elements Cs, Li, Rb, Sr, and Se, as tracers result in similar uptake rates. MethodsThe methodological tests were primarily carried out in a pilot experiment where the five tracers were applied to 1 m depth in lucerne and red beet grown in tube rhizotrons. The dynamics of deep nutrient uptake in chicory was studied in large 4 m deep rhizoboxes. A drought was imposed when roots had reached around 2 m depth. ResultsChicory acquired tracers applied to 3.5 m depth, but we found no compensatory tracer uptake with depth during drought. We found some indications of a compensatory tracer uptake from 2.3 and 2.9 m depth in intercropped chicory. Application of equimolar amounts of trace elements resulted in similar excess tracer concentrations within species. ConclusionChicory acquires nutrients from below 3 m but does not increase deep nutrient uptake as a response to limited topsoil nutrient availability.

plant biology↗

bioRxiv2018

Chicory demonstrates substantial water uptake from below 2 m, but still did not escape topsoil drought

AimsDeep-rooted agricultural crops can potentially utilize deep water pools and thus reduce periods where growth is water limited. Chicory (Cichorium intybus L.) is known to be deep-rooted, but the contribution of deep roots to water uptake under well-watered and drought conditions by the deep root system has not been studied. The aim of this study was to investigate whether chicory could reach 3 m depth within a growing season and demonstrate significant water uptake from the deeper part of the root zone. MethodsWe tested if chicory exposed to either topsoil drought or resource competition from the shallow-rooted species ryegrass (Lolium perenne L.) and black medic (Medicago lupulina L.) would increase deep water uptake in compensation for reduced topsoil water uptake. We grew chicory in 4 m deep soil filled rhizotrons and found that the roots reached 3 m depth within a growing season. ResultsWater uptake from below 1.7 m depth in 2016 and 2.3 m depth in 2017 contributed significantly to chicory water use. However, neither drought nor intercropping increased the deep water uptake. ConclusionChicory benefits from being deep-rooted during drought events, yet deep water uptake cannot compensate for the reduced topsoil water uptake during drought.

plant biology↗