Seasonal development of biomass yield in grass–legume mixtures on different soils and development of above- and belowground organs of Medicago sativa

Grass–legume mixtures are suitable for crop rotations under organic farming. Little attention has been paid to seasonal development of mixtures with alfalfa under field conditions. We investigated the effects of site and cut on herbage and belowground biomass yields of grass–legume mixture and on above- and belowground traits of Medicago sativa. Six sites in southern Germany were monitored during 2011. Dry matter herbage yield ranged from 9 to 16 t ha^?1. The total herbage yield of three cuts per year decreased from 45% to 36% and 19%. The belowground biomass in the upper 30 cm soil layer ranged from 1.7 to 3.8 t ha^?1.There was no seasonal trend. Diameter of the root neck and maximum order of branching of alfalfa increased during the season. The number of nodules per plant decreased from 9.5–17.0 in May to 7.5–13.0 in August. By the last cut, roots with larger diameter created smaller nodules. More branched roots created more nodules independent of their shape. Thinner roots have more active nodules. Plant height, number of stems and inflorescences per plant were higher in July and August than in May. In conclusion, a holistic analysis including above- and belowground traits should be used for the evaluation of fodder crops.     

Architectural and anatomical responses of maize roots to agronomic practices in a semi‐arid environment

Root architecture and anatomy are important determinants of nitrogen (N) and water acquisition, but they are also environmentally plastic to adapt to N and water availability. Therefore, understanding the relationship between root traits and environmental factors is essential for improving N and water acquisition. A field experiment was conducted in the semi‐arid region of the Loess Plateau in northwestern China to quantify the architectural and anatomical root traits of maize (Zea mays L.) in response to plastic film mulching and N fertilization. We compared four treatments: non‐mulching with and without N supply as well as plastic film mulching with and without N supply. Variation existed for all root architecture and anatomy traits within maize root crowns. Crown and brace root angles to the soil line decreased in response to film mulching and N fertilization. Crown roots under plastic film mulching showed a significantly decreased distance to branching, reduced lateral root length, and overall increased root diameter. Similarly, N application significantly decreased the distance to branching, yet induced more compact and denser crown roots, and increased the root diameter. Brace roots exhibited an increased distance to branching, greater lateral root length and density, as well as a larger root diameter in response to plastic film mulching and N fertilization. Additionally, the accumulated number of nodal roots increased greatly under plastic film mulching and N treatments. At the anatomical level, N application reduced the proportion of the root cortical aerenchyma area. In contrast, aerenchyma area, cortex cell size, and late metaxylem vessel diameter were increased as a result of plastic film mulching. These results demonstrate root architectural and anatomical traits respond to mulching practices and N fertilization.     

Soil Aggregate Size and Mycorrhizal Colonization Effect on Root Growth and Phosphorus Accumulation by Berseem Clover

The effects of soil aggregate size and mycorrhizal colonization on phosphorus (P) accumulation and root growth of Berseem clover (Trifolium alexandrinum L.) were studied. Root length and dry weight decreased with increasing aggregate diameter. Colonization of clover plants by arbuscular mycorrhizae (Glomus intraradices Schenck and Smith) improved root growth and P accumulation in all aggregate‐size classes. Although total root length of either mycorrhizal or nonmycorrhizal plants decreased with increasing aggregate diameter, the length of living external hyphae was not affected by aggregate size. Thus, colonized root length was improved by 20% as soil aggregate diameter increased. Total P accumulation per plant decreased with increasing aggregate size. However, total P accumulation per unit root length improved as the size of soil aggregate increased. In our study, mycorrhizal colonization improved total P accumulation and root growth in soil with large aggregates and compensated, in part, for the effect of soil strength.     

Development of populations of rhizobium trifolii and nodulation of subterranean clover following the cropping phase in crop-pasture rotations in southeastern Australia

Soil samples taken from 28 sites following varying periods of cropping in a crop-pasture rotation contained very low populations of Rhizobium trifolii. Populations were less than 10³g^?1R. trifolii of soil for 89% of the sites and were significantly correlated with soil pH. Application of lime resulted in a build-up of R. trifolii in the absence of the host legume, subterranean clover, but when inoculated clover seed was sown the populations built up to satisfactory levels after the first season's growth, regardless of soil pH.The number of nodules per plant was increased by the application of lime, but the plants growing in unlimed soil had fewer, larger nodules. The increase in nodulation with lime on these low-calcium acid soils persisted to the third growing season.     

Short‐term residual N unaffected by forbs in grass‐clover mixtures

We determined the effect on residual nitrogen (N) of including forbs (chicory, ribwort plantain and caraway) in perennial ryegrass‐red clover mixtures. Although soil N inputs during the grassland phase differed markedly between mixtures, in a pot experiment we found no differences in the potentially mineralizable N of the soil or in the dry matter production and N content of the spring barley test crop. The fertilizer value of the grassland mixtures corresponded to 10 g N/m², irrespective of forb inclusion. Thus, the inclusion of nonlegume forbs did not negatively affect short‐term residual N fertility of legume‐based grasslands.     

Roller-Crimper Termination for Legume Cover Crops in North Carolina: Impacts on Nutrient Availability to a Succeeding Corn Crop

Nitrogen (N) release from roll-killed legume cover crops was determined for hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and a hairy vetch + rye (Secale cereale L.) biculture in an organic corn production system in North Carolina, USA. Cover crops were planted at two locations in fall 2008 and 2009, roll-killed in May, and no-till planted with corn (Zea mays L.). Inorganic soil N and mineral N flux were determined using potassium chloride (KCl) extractions and ion-exchange resin (Plant Root Simulator, PRS) probes at 2-week intervals for 12 weeks and compared to fertilized controls of 0 and 168 kg N ha^?1. In 2009, greater plant available N under hairy vetch than under either 0 N control or crimson clover was found, with peak soil N occurring between 4 and 6 weeks after roll kill. Available soil N under crimson clover mulches was less than or equal to 0 N, suggesting net immobilization.     

Bacillus subtilis NRRL B‐30408 inoculation enhances the symbiotic efficiency of Lens esculenta Moench at a Himalayan location

Field‐based experiments were conducted to evaluate the promotion abilities of Bacillus subtilis NRRL B‐30408 for growth of lentil (Lens esculenta Moench) at a mountain location of Indian Himalaya in two consecutive years. Observations were recorded for plant growth, yield, nodulation, root colonization by arbuscular mycorrhizal and endophytic fungi, and other related parameters. A positive influence of bacterial inoculation on plant biomass and yield‐related parameters was recorded in both years. The significant increase in growth and nodule numbers as well as leghaemoglobin and protein concentrations of nodules indicated an enhancement in efficiency of the Rhizobium–legume symbiosis due to bacterial inoculation. An increase in protein concentration was also recorded for shoots, leaves, and seeds. Due to bacterial inoculation, there was an increase in colonization by endophytic fungi and a simultaneous decrease in colonization by arbuscular mycorrhizal fungi in roots. Based on the results of this field study, inoculation with suitable plant growth–promoting rhizobacteria instead of dual inoculation is suggested as a better option for improving the yield and related attributes of a primary dietary legume such as lentil.     

Growth of legume and nonlegume catch crops and residual‐N effects in spring barley on coarse sand

The aim of this experiment was to investigate the growth and residual‐nitrogen (‐N) effects of different catch‐crop species on a low–N fertility coarse sandy soil. Six legumes (white clover [Trifolium repens L.], red clover [Trifolium pratense L.], Persian clover [Trifolium resupinatum L.], black medic [Medicago lupulina L.], kidney vetch [Anthyllis vulneraria L.], and lupin [Lupinus angustifolius L.]), four nonlegumes (ryegrass [Lolium perenne L.], chicory [Cichorium intybus L.], fodder radish [Raphanus sativus L.], and sorrel [Rumex Acetósa L.]), and one mixture (rye/hairy vetch [Secale cereale L./Vicia villosa L.]) were tested in a field experiment with three replicates in a randomized block design. Four reference treatments without catch crops and with N application (0, 40, 80, and 120 kg N ha^–1) to a succeeding spring barley were included in the design. Due to their ability to fix N₂, the legume catch crops had a significantly larger aboveground dry‐matter production and N content in the autumn than the nonlegumes. The autumn N uptake of the nonlegumes was 10–13 kg N ha^–1 in shoots and approx. 9 kg ha^–1 in the roots. The shoot N content of white clover, black medic, red clover, Persian clover, and kidney vetch was 55–67 kg ha^–1, and the root N content in white clover and kidney vetch was approx. 25 kg ha^–1. The legume catch crops, especially white and red clover, seemed to be valuable N sources for grain production on this soil type and their N fertilizer–replacement values in a following unfertilized spring barley corresponded to 120 and 103 kg N ha^–1, respectively. The N fertilizer–replacement values exceeded the N content of shoots and roots.     

Wurzelstudien und Phosphat-Aufnahme von Weidelgras und Rotklee unter Feldbedingungen

Root studies and phosphorus uptake of rye-grass and red clover under field conditions Root parameters (fresh weight, density, surface, length, cation exchange capacity) and phosphate uptake were studied with rye grass and red clover, grown in the field on a brown podsolic soil. In all root parameters, ry grass was superior to red clover. Also, phosphate uptake of rye grass was higher than that of red clover. The greatest difference between both species was found in root length, that of rye grass being about five times longer than that of red clover. Rye grass had longer root hairs than red clover; whereas root diameter of clover was about twice as thick the average rye grass. Significant correlations were observed between root parameters and phosphate uptake in the plants studied. The highest correlation coefficients were obtained for the relationship P-uptake versus root length (clover 0.91***, grass 0.87***) and P-uptake versus root fresh weight (clover 0.92***, grass 0.88***). The phosphate uptake per unit root parameters was significantly higher in red clover, compared with rye grass, for the parameters root fresh weight, cation exchange capacity and root length. Because of this high P-uptake rate for clover it is assumed that clover also requires a higher P-concentration in soil solution as compared with grass. Thus grass may still grow with low P concentrations in the soil solution without P deficiency at which clover cannot grow. It is for this reason that in mixed swards clover is depressed by grass, if the available P in the soil is low.     

Variation in morphology and seed production of snow clover [<Emphasis Type="Italic">Trifolium pratense</Emphasis> L. subsp. <Emphasis Type="Italic">nivale</Emphasis> (Koch) Arcang.] germplasm from the Rhaetian Alps,Italy

A recent approach to restoration of degraded mountain landscapes (e.g. ski slopes) recommend to sow seed mixtures including ‘site-specific’ species, i.e. native germplasm adapted to the prevailing conditions and ecologically compatible with the area of intervention. To better exploit the potential of these species and enhance their spread in revegetation projects, deeper knowledge is needed, however, on the existing variation in their germplasm, particularly for economically useful traits such as seed yield. Snow clover is one of the recommended ‘site-specific’ legumes. This study evaluated 12 populations of snow clover, collected in three valleys of the Rhaetian Alps, Italy, to assess their variation and highlight any promising material. The evaluation encompassed a mountain and a lowland site, to verify the behaviour of the germplasm also in one environment markedly different from that of origin. Differences among valleys were observed for flower colour, growth habit and type, flowering time and susceptibility to mildew, although the overall pattern of phenotypic diversity was similar among valleys. Some effect of the evaluation site on the expression of morphological and seed production traits, and on the overall diversity, was also evident. Furthermore, the lowland site experienced very high plant mortality towards the end of the first growing season. Individual populations proved a valuable source of variation for seed production. Some populations, in particular, were worth of attention for a possible selection of high-seed-yielding snow clover cultivars. An assessment of the mating system suggested a lack of self-tripping or an almost absolute self-incompatibility in snow clover.     

Root development of winter wheat in erosion‐affected soils depending on the position in a hummocky ground moraine soil landscape

Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g^?1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity.     

Performance of legume–grass mixtures in the West Balkan region

Three perennial legumes (alfalfa, red clover and birdsfoot trefoil) and four cool-season perennial grasses (orchardgrass, tall fescue, Italian ryegrass and red fescue) were grown in legume–grass combinations and in pure stands of individual species, at three locations in the West Balkan region (Novi Sad, Banja Luka and Pristina) in the period from 2012 to 2015. The study evaluated dry matter yield, legume–grass–weed proportion and forage quality. High annual forage yield of legume–grass mixtures can be obtained with proper selection of species and an appropriate legume–grass ratio. However, high and stable yield, particularly in the case of grasses, depends on the amount and schedule of precipitation as well as the cutting time. The mixtures and legume pure stands achieved better forage production both per cutting and on the annual basis and had better forage quality than grass pure stands.     

Underground communication of root hormones by common mycorrhizal network between trifoliate orange and white clover

Common mycorrhizal network (CMN) links up several coexisting plant individuals via underground root communication for resource sharing, while it is not known whether phytohormones participate in such communication. A two-chambered rootbox separated through 37-μm mesh was used to establish the CMN by Diversispora spurca between trifoliate orange (TO) and white clover (WC). After 20 weeks of inoculation, the CMN was established, as evident from high mycorrhizal buildup under supplier (mycorrhizal inoculation) TO–target (non-mycorrhizal inoculation) WC association. This CMN was eventually responsible for the significant increase in plant biomass of these associated plants. CMN decreased root abscisic acid (ABA) level in supplier and target plants, but increased root indole-3-acetic acid (IAA) level in supplier plant alone. CMN mediated significantly higher gibberellins (GAs) and zeatin riboside (ZR) concentration in roots of target plant, leaving supplier plant unaffected. Root ZR was bidirectionally transferred through the CMN. A higher root methyl jasmonate (MeJA) concentration was observed in supplier WC–target TO or supplier TO–supplier WC association, indicating an unidirectional communication from WC to TO. It suggested that except IAA, GAs, brassinosteroid (BR), and ABA, root MeJA and ZR were apparently involved in the underground communication by CMN.     

Establishment of Hybrid Arctic Bramble under Field Conditions

The effect of different factors on plant diameter and yield in hybrid arctic bramble (Rubus arcticus nothosubsp. stellarcticus) was examined in two field experiments with a factorial design. The studied factors included planting time (August, September, May or June), plant type (bare-rooted or potted plants) and ground cover (no ground cover or mulching with a dark plastic film). Development of bare-rooted and potted plants did not differ when transplanted in the autumn and in May. Potted plants developed better than bare-rooted plants when transplanted in June. In one year, plants transplanted in May developed best, while in another, plants transplanted in the autumn developed best. Mulching with a dark plastic film improved plant development. The rate of vegetative development during the first growth season was reflected in the yields in both the first and the second harvest year; the greater the plant diameter after the first growth season, the higher the yield.     

Root growth dynamics of spring cereals with discontinuation of mouldboard ploughing

A vigorous root system is essential for efficient use of plant nutrients. This paper focuses on root growth and its response to tillage changes in the most fertile soil horizon, 0–40 cm depth. The field experiment was established in 1995 on clay soil, with 45–50% clay and 5.5% organic matter in the topsoil. Three tillage treatments were mouldboard plough to a depth of 20 cm (conventional), field cultivator to a depth of 8 cm, and no primary tillage (conservation). The field had an oat (Avena sativa L.)–barley (Hordeum vulgare L.) crop rotation. In 1997–1998 and 2000, root distribution during the growing season was evaluated by a non-destructive minirhizotron (MR) and video recording method. Root length density and root diameter were also measured once a season (1997 and 1998) by destructive root sampling and image analysis of washed roots. At shoot elongation, root numbers increased more under conventional than conservation tillage, at soil depth of 10–25 cm. The effect was clear for both barley (1997) and oat (2000) with maximum root numbers of 175 and 210 per 100 cm² by mouldboard ploughing, but 120 and 170 per 100 cm² under unploughed conditions (in the whole 0–0.4 m region). The suboptimal condition of unploughed soil was also indicated by lower shoot nutrient contents at tillering (studied in 1997) and by higher penetrometer resistance (studied in 1998, 2000) and lower macroporosity (studied in 2000) at 10–25 cm soil depth. Root growth dynamics were similar for both plant species. Root diameter was not significantly affected by the tillage treatments. Discontinuation of mouldboard ploughing reduced root growth (P<0.05) within this clay soil 5 years after the tillage change, although conservation tillage preserved more water for plant use. The data show that a clay soil can be too dense for optimal rooting during the 3rd–6th-years after discontinuation of ploughing.     

Root traits of different crops under rainfed conditions in the High Barind Tract of Bangladesh

Root traits of six different crops grown on residual soil moisture in the post–rainy season in the High Barind Tract (HBT) of Bangladesh were investigated to better understand their adaptation to this moisture‐limited environment. Deep‐rooting chickpea is the currently favored rainfed crop grown after rainy‐season rice in the HBT, but it is necessary to identify alternative crops to chickpea in order to avoid buildup of pests and diseases. Averaged over 2 y, barley (1.72 Mg ha^–1) produced significantly more grain than chickpea (1.4 Mg ha^–1) which, in turn, yielded better than linseed (1.0 Mg ha^–1), wheat (0.93 Mg ha^–1), and mustard (0.77 Mg ha^–1). Lentil did not produce any grain at all. Grain yield for all crops increased as total root length increased above a threshold value of 0.05 to 0.1 km m^–2. In general, grain yield increased as the proportion of total root produced below 60 cm depth increased, although barley also had thin roots that could more effectively extract soil moisture. Expression of root traits varied considerably between seasons, which was attributable to the different rainfall patterns and bulk‐density characteristics of the soil profile in the 2 years of the study. Although favorable root traits, particularly rooting ability below 60 cm, are a prerequisite for acceptable yield levels of crops grown on residual soil moisture in the HBT, it is recognized that farmers' choice of a post‐rice crop will depend on its economic return or food‐security value.     

Plant root morphology and soil biological indicators under primary development of various swards

Plant nutrition conditions are limited in naturally acidic soil due to harmful hydrogen and aluminium ions. More favourable conditions for plant nutrition (soil liming) will affect root qualitative and quantitative parameters and influence ecosystem stability. Four legume–grass swards were cultivated. The swards were a combination of one species of legume and two species of grasses: Trifolium pratense L., Trifolium repens L., Trifolium hybridum L., Medicago sativa L. (each of 50%) with Phleum pratense L. (35%) and Poa pratensis L. (15%). The aim of this study is to evaluate the root morphological and soil biological indicators of legume–grass swards under the first two years of development in soils with different pH levels.

Sward ecosystem development depends on the pH of the soil, sward species composition and soil biota. During the first year of sward development, soil pH had a significant influence on the morphology of root system. Sward‘s root mass and total root length was 2.4 and 2.2 times bigger in naturally acidic soil. This resulted in a change of biological parameters.

In the second year of sward development, soil pH had no significant influence on sward‘s root mass. However, under the impact of different soil pH, various sward‘s root systems were formed and the root C:N ratio had changed. It is observed that, regardless of the sward species composition and the year of development, at higher root C:N ratio soil microbial biomass was higher and CO₂ emissions were lower in swards in naturally acidic soils.

Regardless of soil pH, different types of clover–grass swards promoted organic carbon immobilization in microbial biomass and, at the same time, stabilized the sward ecosystem in the top soil layer (soil respiration in 0–10 and 10–20?cm layers was lower) more effectively than the alfalfa–grass sward.     

Quantification of Aluminum-Induced Changes in Wheat Root Architecture by X-ray Microcomputed Tomography

Root architectural traits are of fundamental importance for plant performance, especially under unfavorable soil conditions. This study examined the effect of aluminum (Al) toxicity in different growing media (nutrient solutions and soil) on root architecture of two wheat (Triticum aestivum L.) cultivars with different Al tolerances. Seedlings were grown in acidic and limed soil and in two contrasting nutrient solutions. Root systems of soil-grown plants were scanned using x-ray microcomputed tomography (µCT) while that of nutrient solution–grown plants were assesses using WinRhizo, 3 and 5 days after planting (DAP), respectively. Aluminum caused significant reduction of all examined root traits (number of seminal roots, root length, length of the longest seminal root, root surface area, and root volume). Growth in acidic soil caused significant reduction in root length, length of the longest seminal root, and root surface area at 5 DAP. Soil-grown plants produced a larger root system compared to plants grown in nutrient solutions. Aluminum toxicity–induced differences of root traits were also found between different nutrient solutions. Beside the well-known reduction of root length, Al toxicity had a profound effect on other root architectural traits. X-ray µCT has revealed root architectural changes under specific conditions of acidic, Al-toxic soil. Differences obtained in Al-induced effects on root architecture between different nutrient solutions as well as between different growing systems emphasize the need for further study of root architecture, especially under specific conditions of Al toxicity in acidic soils.     

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

Cover crops (CC) can promote nutrient retention and recycling for main crops yet may also promote soilborne pathogens or suppress beneficial root symbionts such as arbuscular mycorrhizal fungi (AMF). We investigated how root fungal communities of main crop are affected by preceding CC monocultures and mixtures and by main crop identity. We expected that AMF abundance and diversity in main crops are promoted by AM-host CC, and suppressed by non-AM-host CC, and that mixtures of CC species can promote beneficial and suppress pathogenic root fungi. Our full-factorial field experiment comprised crop rotation in sand soil with different CC treatments (monocultures of radish [AM non-host], ryegrass, clover, vetch [AM hosts], mixtures of radish + vetch, ryegrass + clover and fallow) and two main crops (oat and endive). At peak crop growth, we investigated the root fungal communities in the main crops using microscopy and high throughput sequencing (Illumina MiSeq). Cover crop identity was of prime importance and CC legacy overruled main crop identity in determining root fungal communities in main crops. Compared with fallow, CC with ryegrass increased AMF colonization and richness in both main crops and of non-AMF in oat. Legacies of ryegrass, ryegrass + clover and vetch resulted in distinct root fungal communities in the main crops, while the legacy of CC with radish were similar to the legacy of fallow. Root fungal community in crops after clover had highest abundance of representative fungal pathogens in contrast with the other CC treatments that resulted in fungal communities where pathogens were scarce. Oppositely to expected, CC mixtures did not enhance fungal symbionts or suppressed pathogens. Overall, fungal communities in roots of the main crops in our field experiment were determined by the preceding CC species in monoculture, rather than by the CC AMF preference or functional group. This research highlights that the choice of CC determines the root fungal community in main crop which may influence crop quality.     

Root trait plasticity and plant nutrient acquisition in phosphorus limited soil

To overcome soil nutrient limitation, many plants have developed complex nutrient acquisition strategies including altering root morphology, root hair formation or colonization by arbuscular mycorrhizal fungi (AMF). The interactions of these strategies and their plasticity are, however, affected by soil nutrient status throughout plant growth. Such plasticity is decisive for plant phosphorus (P) acquisition in P‐limited soils. We investigated the P acquisition strategies and their plasticity of two maize genotypes characterized by the presence or absence of root hairs. We hypothesized that in the absence of root hairs plant growth is facilitated by traits with complementary functions, e.g., by higher root mycorrhizal colonization. This dependence on complementary traits will decrease in P fertilized soils. At early growth stages, root hairs are of little benefit for nutrient uptake. Regardless of the presence or absence of root hairs, plants produced average root biomass of 0.14 g per plant and exhibited 23% root mycorrhizal colonization. At later growth stages of maize, contrasting mechanisms with functional complementarity explained similar plant biomass production under P limitation: the presence of root hairs versus higher root mycorrhizal colonization (67%) favored by increased fine root diameter in absence of root hairs. P fertilization decreased the dependence of plant on specific root traits for nutrient acquisition. Through root trait plasticity, plants can minimize trade‐offs for developing and maintaining functional traits, while increasing the benefit in terms of nutrient acquisition and plant growth. The present study highlights the plasticity of functional root traits for efficient nutrient acquisition strategies in agricultural systems with low nutrient availability.