Root Growth Patterns Research Articles

The MADS-box gene XAANTAL1 participates in Arabidopsis thaliana primary root growth and columella stem cell patterns in response to ROS, via direct regulation of PEROXIDASE 28 and RETINOBLASTOMA RELATED.

The balance between cell growth, proliferation and differentiation emerges from gene regulatory networks coupled to various signal transduction pathways, including reactive oxygen species (ROS) and transcription factors (TFs), enabling developmental responses to environmental cues. The Arabidopsis thaliana's primary root has become a valuable system for unraveling such networks. Recently, the role of TFs that mediate the ROS's inhibition of primary root growth has begun to be characterized. This study demonstrates that the MADS-box transcription factor XAANTAL1 (XAL1) is an essential regulator of hydrogen peroxide (H2O2) in primary root growth and root stem cell niche identity. Interestingly, our findings suggest that XAL1 acts as a positive regulator of H2O2 concentration in the root meristem by directly regulating genes involved in oxidative stress response, such as PEROXIDASE 28 (PER28). Moreover, we found that XAL1 is necessary for the H2O2-induced inhibition of primary root growth through the negative regulation of peroxidase and catalase activities. Furthermore, XAL1, in conjunction with RETINOBLASTOMA-RELATED (RBR), is essential for positively regulating the differentiation of columella stem cells and for participating in primary root growth inhibition in response to oxidative stress induced by H2O2 treatment.

Integrated deep banding and fertigation of phosphorus improves cotton yield by regulating root spatial distribution and growth

Context or problemTraditionally, 100 % phosphorus (P) fertilizer application as a band at various depths before sowing significantly influenced crop root growth and yield by reducing P fixation and optimizing its spatial distribution. However, with the advent of drip fertigation in Xinjiang, China, P fertilization practices have shifted from 100 % basal to a combination of basal and fertigation for enhanced P nutrition in cotton. Despite this, the impact of pre-sowing P band application on cotton growth under drip fertigation remains unclear. Objective or research questionThis study aimed to determine the optimal P fertilizer banding depth for cotton under a drip fertigation system. MethodsField trials were conducted comparing different basal P fertilizer application depths (5 cm, 15 cm, and 25 cm, denoted as D5, D15, and D25, respectively) with 50 % of the P rate and the remaining 50 % applied as topdressing via drip fertilization. A control (CK) involving 50 % broadcasted P fertilizer and 50 % topdressed P was included. The study focused on the effects of P application depth on soil P availability, root growth patterns, P utilization, and cotton yield. ResultsAt the boll opening stage, the D15 treatment exhibited a significant 18.69 %-49.76 % increase in available phosphorus in the 10–40 cm soil layer compared to the CK. During the peak boll to boll opening stage, the D15 treatment significantly outperformed the CK in terms of total root biomass density (11.62 %-17.54 %), total root length (16.75 %-24.81 %), total root surface area (23.07 %-37.59 %), and total root volume (20.69 %-26.23 %). Moreover, root activity and growth parameters were notably higher in the D15 treatment within the 10–40 cm soil layer. ConclusionsApplying 50 % of the P fertilizer as a band at a 15 cm depth before planting drip-irrigated cotton is optimal. This practice enhances soil P availability, stimulates root growth and distribution, and ultimately improves P utilization and cotton yield. Implications or significanceBanding P fertilizer at a 15 cm depth in combination with drip fertigation demonstrates superior yield benefits. This technology offers a novel approach to fertilizer application, enhancing nutrient use efficiency and crop productivity in drip-irrigated systems.

An ecotype-specific effect of osmopriming and melatonin during salt stress in Arabidopsis thaliana

BackgroundNatural populations of Arabidopsis thaliana exhibit phenotypic variations in specific environments and growth conditions. However, this variation has not been explored after seed osmopriming treatments. The natural variation in biomass production and root system architecture (RSA) was investigated across the Arabidopsis thaliana core collection in response to the pre-sawing seed treatments by osmopriming, with and without melatonin (Mel). The goal was to identify and characterize physiologically contrasting ecotypes.ResultsVariability in RSA parameters in response to PEG-6000 seed osmopriming with and without Mel was observed across Arabidopsis thaliana ecotypes with especially positive impact of Mel addition under both control and 100 mM NaCl stress conditions. Two ecotypes, Can-0 and Kn-0, exhibited contrasted root phenotypes: seed osmopriming with and without Mel reduced the root growth of Can-0 plants while enhancing it in Kn-0 ones under both control and salt stress conditions. To understand the stress responses in these two ecotypes, main stress markers as well as physiological analyses were assessed in shoots and roots. Although the effect of Mel addition was evident in both ecotypes, its protective effect was more pronounced in Kn-0. Antioxidant enzymes were induced by osmopriming with Mel in both ecotypes, but Kn-0 was characterized by a higher responsiveness, especially in the activities of peroxidases in roots. Kn-0 plants experienced lower oxidative stress, and salt-induced ROS accumulation was reduced by osmopriming with Mel. In contrast, Can-0 exhibited lower enzyme activities but the accumulation of proline in its organs was particularly high. In both ecotypes, a greater response of antioxidant enzymes and proline accumulation was observed compared to mechanisms involving the reduction of Na+ content and prevention of K+ efflux.ConclusionsIn contrast to Can-0, Kn-0 plants grown from seeds osmoprimed with and without Mel displayed a lower root sensitivity to NaCl-induced oxidative stress. The opposite root growth patterns, enhanced by osmopriming treatments might result from different protective mechanisms employed by these two ecotypes which in turn result from adaptive strategies proper to specific habitats from which Can-0 and Kn-0 originate. The isolation of contrasting phenotypes paves the way for the identification of genetic factors affecting osmopriming efficiency.

Fine Root Density Dynamics and Carbon Stock of Eucalyptus spp.: Interplay of Age, Genotype, and Edaphoclimatic Conditions.

Roots play a fundamental role in forest ecosystems, but obtaining samples from deep layers remains a challenging process due to the methodological and financial efforts required. In our quest to understand the dynamics of Eucalyptus roots, we raise three fundamental questions. First, we inquire about the average extent of the roots of two contrasting Eucalyptus genotypes. Next, we explore the factors that directly influence the growth and depth of these roots, addressing elements such as soil type, climate, and water availability. Lastly, we investigate how the variation in Eucalyptus species may impact root growth patterns, biomass, and carbon stock. In this study, we observed that the maximum root depth increased by an average of 20% when genotypes were grown on sites with higher water availability (wet site). E. urophylla stands had a higher biomass and carbon stock (5.7 Mg C ha-1) of fine roots when cultivated on dry sites (annual rainfall~727 mm) than the wet sites (annual rainfall~1590 mm). In E. grandis × E. camaldulensis stands, no significant differences were observed in the stock of fine root biomass (3.2 Mg C ha-1) between the studied environments. Our results demonstrated that genotypes with greater drought tolerance (E. grandis × E. camaldulensis) tend to maintain higher stocks of fine root biomass (3.2-6.3 Mg ha-1) compared to those classified as plastic (E. urophylla), regardless of the edaphoclimatic conditions of the cultivation site. Finally, our research helps understand how Eucalyptus trees adapt to their environment, aiding sustainable forest management and climate change mitigation. We also provide a practical tool to estimate underground biomass, assisting forest managers and policymakers in ensuring long-term forest sustainability.

Adaptation of the maize seedling seminal roots to srought: Essential role of plasma membrane H+-ATPases activity

To understand how maize plants adapt to drought, this study examines the role of plasma membrane proton pumps in root growth. This study delves into the physiological mechanisms through which maize plants respond to drought conditions, with a particular emphasis on elucidating the crucial role played by plasma membrane proton pumps in facilitating adaptive changes in root growth. Our results underscore the indispensable nature of these pumps in orchestrating precise modulation of root growth patterns during drought stress, highlighting their profound significance in stress responses. Additionally, the study reveals that osmotic stress alters lipid profiles in the plasma membrane, potentially impacting its functioning and the activity of membrane proteins. To understand the role of plasma membrane (PM) H<sup>+</sup>-ATPases in the adaptative response to osmotic stress and in the regulation of root growth in maize, we studied the gene expression and enzyme activity of PM H<sup>+</sup>-ATPases, as well as the changes in plant biomass and total root growth, in the seedlings of two maize cultivars: the drought-tolerant Calo cultivar and the drought-sensitive Abelardo. The seedlings were exposed to simulated drought for 24 h (treatment with 20% PEG). The enzyme activity and gene expression of the <i>MHA4</i> H<sup>+</sup>-ATPase increased in the Calo variety but declined in Abelardo plants treated with PEG. The growth of roots in Abelardo plants exposed to 24 h of PEG treatment was reduced to almost 50% of the control. Conversely, for the Calo cultivar, there was no remarkable morpho-physiological difference between the roots of stressed and non-stressed plants. Therefore, the activity of the PM H<sup>+</sup>-ATPase seems to be an important factor for proper root growth during the adaptation of maize to drought. In addition, osmotic stress also induced changes in the levels of saturated polyisoprenoid alcohols in the plasma membrane fraction of maize roots. The increased levels of this class of lipids might modulate the physico-chemical properties of the PM lipid bilayer and thus affect its functioning and modify the activity of membrane proteins, such as PM H<sup>+</sup>-ATPases.

Induction and study of hairy root growth pattern in Indian ginseng medicinal plant using Agrobacterium rhizogenes

Induction and study of hairy root growth pattern in Indian ginseng medicinal plant using Agrobacterium rhizogenes

Genotypic differences in systemic root responses to mechanical obstacles.

As roots grow through the soil to forage for water and nutrients, they encounter mechanical obstacles such as patches of dense soil and stones that locally impede root growth. Here, we investigated hitherto poorly understood systemic responses of roots to localised root impedance. Seedlings of two wheat genotypes were grown in hydroponics and exposed to impenetrable obstacles constraining the vertical growth of the primary or a single seminal root. We deployed high-resolution in vivo imaging to quantify temporal dynamics of root elongation rate, helical root movement, and root growth direction. The two genotypes exhibited distinctly different patterns of systemic responses to localised root impedance, suggesting different strategies to cope with obstacles, namely stress avoidance and stress tolerance. Shallower growth of unconstrained seminal roots and more pronounced helical movement of unconstrained primary and seminal roots upon localised root impedance characterised the avoidance strategy shown by one genotype. Stress tolerance to localised root impedance, as exhibited by the other genotype, was indicated by relatively fast elongation of primary roots and steeper seminal root growth. These different strategies highlight that the effects of mechanical obstacles on spatiotemporal root growth patterns can differ within species, which may have major implications for resource acquisition and whole-plant growth.

Early root phenotyping in sweetpotato (Ipomoea batatas L.) uncovers insights into root system architecture variability.

We developed a novel, non-destructive, expandable, ebb and flow soilless phenotyping system to deliver a capable way to study early root system architectural traits in stem-derived adventitious roots of sweetpotato (Ipomoea batatas L.). The platform was designed to accommodate up to 12 stems in a relatively small area for root screening. This platform was designed with inexpensive materials and equipped with an automatic watering system. To test this platform, we designed a screening experiment for root traits using two contrasting sweetpotato genotypes, 'Covington' and 'NC10-275'. We monitored and imaged root growth, architecture, and branching patterns every five days up to 20 days. We observed significant differences in both architectural and morphological root traits for both genotypes tested. After 10 days, root length, surface root area, and root volume were higher in 'NC10-275' compared to 'Covington'. However, average root diameter and root branching density were higher in 'Covington'. These results validated the effective and efficient use of this novel root phenotyping platforming for screening root traits in early stem-derived adventitious roots. This platform allowed for monitoring and 2D imaging of root growth over time with minimal disturbance and no destructive root sampling. This platform can be easily tailored for abiotic stress experiments, and permit root growth mapping and temporal and dynamic root measurements of primary and secondary adventitious roots. This phenotyping platform can be a suitable tool for examining root system architecture and traits of clonally propagated material for a large set of replicates in a relatively small space.

Phloem anatomy restricts root system architecture development: theoretical clues from in silico experiments

Abstract Plant growth and development involve the integration of numerous processes, influenced by both endogenous and exogenous factors. At any given time during a plant’s life cycle, the plant architecture is a readout of this continuous integration. However, untangling the individual factors and processes involved in the plant development and quantifying their influence on the plant developmental process is experimentally challenging. Here we used a combination of computational plant models (CPlantBox and PiafMunch) to help understand experimental findings about how local phloem anatomical features influence the root system architecture. Our hypothesis was that strong local phloem resistance would restrict local carbon flow and locally modify root growth patterns. To test this hypothesis, we simulated the mutual interplay between the root system architecture development and the carbohydrate distribution to provide a plausible mechanistic explanation for several experimental results. Our in silico experiments highlighted the strong influence of local phloem hydraulics on the root growth rates, growth duration and final length. The model result showed that a higher phloem resistivity leads to shorter roots due to the reduced flow of carbon within the root system. This effect was due to local properties of individual roots, and not linked to any of the pleiotropic effects at the root system level. Our results open a door to a better representation of growth processes in a plant computational model.

Root distribution, soil water depletion, and water productivity of sweet corn under deficit irrigation and biochar application

Root modifications can play a vital role in crop adjustments to soil water deficit. It is important to understand root growth and soil water depletion patterns to develop effective cropping systems, especially in semi-arid regions like Texas High Plains (THP). This study evaluated root growth, soil water depletion, and water productivity (WP) of sweet corn under three deficit irrigation treatments [100 %, 70 % and 40 % crop evapotranspiration (ETc)] and biochar application (hardwood and softwood). The experimental units were replicated 4 times in a split-plot design. The results revealed no interaction between irrigation and biochar treatments for almost all measured parameters. The 70 % ETc treatment increased the root length density (RLD) over 100 % ETc during 2019, while no differences were observed among irrigation treatments in 2020. Both deficit irrigations (70 % and 40 % ETc) increased soil water depletion compared to 100 % ETc, the highest being in 40 % ETc. The 70 % ETc maintained a similar yield and increased WP by 21 % compared to 100 % ETc across two years. However, 40 % ETc resulted in significant decline in yield and WP in 2020. The hardwood biochar increased RLD over no biochar treatment without affecting the soil water status and WP. Long-term studies are needed to investigate biochar effects beyond two years of application. In case of limited water availability, 70 % ETc can be recommended as an alternative to 100 % ETc in the THP of the US.

A comparative study of fifteen cover crop species for orchard soil management: water uptake, root density traits and soil aggregate stability

Increasing the use of cover crops (CCs) is a necessity in sustainable viticulture, although it might clash with possible excessive competition towards vines. Especially in a climate-change scenario, the latter feature should be minimized while maintaining ecosystem services. Aimed at identifying CCs for vineyard floor management, the trial characterized several species according to their evapotranspiration (ET) rates, root growth patterns, and soil aggregate stability potential. The study was performed in 2020 in Piacenza (Northern Italy) on 15 CC species grown in pots kept outdoor and classified as grasses (GR), legumes (LE) and creeping (CR). Together with bare soil (control), they were arranged in a complete randomized block design. CCs ET was assessed through a gravimetric method, starting before mowing and then repeated 2, 8, 17 and 25 days thereafter. Above-ground dry biomass (ADW), root length density (RLD), root dry weight (RDW) and root diameter class length (DCL) were measured, and mean weight diameter (MWD) was calculated within 0–20 cm depth. Before mowing, ET was the highest in LE (18.6 mm day−1) and the lowest in CR (8.1 mm day−1) the latter being even lower than the control (8.5 mm day−1). The high ET rates shown by LE were mainly related to very fast development after sowing, rather than to a higher transpiration per unit of leaf area. After mowing, the 15 species’ ET reduction (%) plotted vs leaf area index (LAI, m2 m−2) yielded a very close fit (R2 = 0.94), suggesting that (i) a linear decrease in water use is expected anytime starting with an initial LAI of 5–6, (ii) a saturation effect seems to be reached beyond this limit. Selection of cover crop species to be used in the vineyard was mainly based on diurnal and seasonal water use rates as well as dynamic and extent of root growth patterns. Among GR, Festuca ovina stood out as the one with the lowest ET due to its “dwarfing” characteristics, making it suitable for a permanent inter-row covering. CR species confirmed their potential for under-vine grassing, assuring rapid soil coverage, lowest ET rates, and shallow root colonization.

Comparative Transcriptome Analysis of Tolerant and Sensitive Genotypes of Common Bean (Phaseolus vulgaris L.) in Response to Terminal Drought Stress

We conducted a genome-wide transcriptomic analysis of three drought tolerant and sensitive genotypes of common bean to examine their transcriptional responses to terminal drought stress. We then conducted pairwise comparisons between the root and leaf transcriptomes from the resulting tissue based on combined transcriptomic data from the tolerant and sensitive genotypes. Our transcriptomic data revealed that 491 (6.4%) DEGs (differentially expressed genes) were upregulated in tolerant genotypes, whereas they were downregulated in sensitive genotypes; likewise, 396 (5.1%) DEGs upregulated in sensitive genotypes were downregulated in tolerant genotypes. Several transcription factors, heat shock proteins, and chaperones were identified in the study. Several DEGs in drought DB (data Base) overlapped between genotypes. The GO (gene ontology) terms for biological processes showed upregulation of DEGs in tolerant genotypes for sulfate and drug transmembrane transport when compared to sensitive genotypes. A GO term for cellular components enriched with upregulated DEGs for the apoplast in tolerant genotypes. These results substantiated the temporal pattern of root growth (elongation and initiation of root growth), and ABA-mediated drought response in tolerant genotypes. KEGG (kyoto encyclopedia of genes and genomes) analysis revealed an upregulation of MAPK (mitogen activated protein kinase) signaling pathways and plant hormone signaling pathways in tolerant genotypes. As a result of this study, it will be possible to uncover the molecular mechanisms of drought tolerance in response to terminal drought stress in the field. Further, genome-wide transcriptomic analysis of both tolerant and sensitive genotypes will assist us in identifying potential genes that may contribute to improving drought tolerance in the common bean.

Understanding the Role of Physiological and Agronomical Traits during Drought Recovery as a Determinant of Differential Drought Stress Tolerance in Barley

The fast and efficient recovery could be an important trait defining the efficacy of plant drought adaptation. In this work, we aimed to develop a set of simple and appropriate physiological proxies that could be used as reliable indicators to predict plant drought responses and validate the role of specific physiological traits such as root length, stomata density, and residual transpiration, in the drought tolerance and recovery in barley. Eighty barley (Hordeum vulgare L.) genotypes were subjected to progressive droughting until the soil moisture level reached 10%, followed by rewatering. Plants were visually scored at the end of drought period and two weeks after rewatering. SPAD values and chlorophyll fluorescence Fv/Fm ratio were also measured, alongside with stomatal density (SD) and residual transpiration (RT). The same genotypes were germinated in paper rolls treated with 15% (w/v) of polyethylene glycol (PEG) 8000 by quantification of changes in the root growth patterns. Responses to drought stress varied among the genotypes, and drought tolerance and recovery scores were significantly correlated with each other. Changes in SPAD value, Fv/Fm ratio and root length were significantly correlated with the drought tolerance and recovery indices. Both indices correlated strongly with the SD and RT of irrigated plants, although in an unexpected direction. We have also correlated the extent of plants’ drought tolerance to their ability to grow in saline soils (a condition often termed a “physiological drought”) and found a positive association between these two traits. The fact that drought tolerant genotype also possessed higher salinity tolerance implies some common mechanisms conferring both traits. Plants having less SD and more RT under irrigated conditions showed higher drought tolerance. It is concluded that lower SD and higher RT under optimal conditions may be used as proxies for drought tolerance in barley.

Growing at the right time: interconnecting the TOR pathway with photoperiod and circadian regulation.

Plants can adjust their growth to specific times of the day and season. Different photoperiods result in distinct growth patterns, which correlate with specific carbon-partitioning strategies in source (leaves) and sink (roots) organs. Therefore, external cues such as light, day length, and temperature need to be integrated with intracellular processes controlling overall carbon availability and anabolism. The target of rapamycin (TOR) pathway is a signalling hub where environmental signals, circadian information, and metabolic processes converge to regulate plant growth. TOR complex mutants display altered patterns of root growth and starch levels. Moreover, depletion of TOR or reduction in cellular energy levels affect the pace of the clock by extending the period length, suggesting that this pathway could participate in circadian metabolic entrainment. However, this seems to be a mutual interaction, since the TOR pathway components are also under circadian regulation. These results strengthen the role of this signalling pathway as a master sensor of metabolic status, integrating day length and circadian cues to control anabolic processes in the cell, thus promoting plant growth and development. Expanding this knowledge from Arabidopsis thaliana to crops will improve our understanding of the molecular links connecting environmental perception and growth regulation under field conditions.

Phenology of fine root and shoot using high frequency temporal resolution images in a temperate larch forest

Understanding tree phenology reveals the underlying mechanisms through plant functional and productive activities and carbon sinks in forest ecosystems. However, previous research on tree phenology has focused on shoot dynamics rather than tree root dynamics. Here, we aimed to explore seasonal temperature patterns of daily-based root and shoot dynamics by capturing high frequency information of plant images in a larch forest. Additionally, we focused on seasonal changes in fine root color, which white roots absorb nutrients or water; brown roots undergo secondary structural development with transport resources. We monitored continuous images using an automated digital camera for shoot dynamics and a flatbed scanner for the fine root dynamics. Using the images, we analyzed the relationship between temperature and plant area index as shoot growth status and total root-area proportion of white and brown roots. Larch shoot production had a single mountain-shaped peak, and there was a positive correlation between plant area index and air temperature. Fine root production had a bimodal root-growth pattern, with two peaks in early summer and late autumn. Soil temperature was positively correlated with white root proportion and negatively correlated with brown root proportion. We identified differences between shoots and roots regarding temperature relationships. In particular, the automated flatbed scanner method for root dynamics allowed the collection of detailed bimodal patterns of root production with a shift from whitening to browning color, which had previously been overlooked. Such high frequency temporal resolution analysis can illustrate the in-depth of mechanisms of fine-root and shoot phenology through different stages of plant development in terms of growth and senescence.

Novel QTL Associated with Aerenchyma-Mediated Radial Oxygen Loss (ROL) in Rice (Oryza sativa L.) under Iron (II) Sulfide.

In rice, high radial oxygen loss (ROL) has been associated with the reduction in the activity of methanogens, therefore reducing the formation of methane (CH4) due to the abundance in application of nitrogen (N)-rich fertilizers. In this study, we evaluated the root growth behavior and ROL rate of a doubled haploid (DH) population (n = 117) and parental lines 93-11 (P1, indica) and Milyang352 (P2, japonica) in response to iron (II) sulfide (FeS). In addition, we performed a linkage mapping and quantitative trait locus (QTL) analysis on the same population for the target traits. The results of the phenotypic evaluation revealed that parental lines had distinctive root growth and ROL patterns, with 93-11 (indica) and Milyang352 (japonica) showing low and high ROL rates, respectively. This was also reflected in their derived population, indicating that 93.2% of the DH lines exhibited a high ROL rate and about 6.8% had a low ROL pattern. Furthermore, the QTL and linkage map analysis detected two QTLs associated with the control of ROL and root area on chromosomes 2 (qROL-2-1, 127 cM, logarithm of the odds (LOD) 3.04, phenotypic variation explained (PVE) 11.61%) and 8 (qRA-8-1, 97 cM, LOD 4.394, PVE 15.95%), respectively. The positive additive effect (2.532) of qROL-2-1 indicates that the allele from 93-11 contributed to the observed phenotypic variation for ROL. The breakthrough is that the qROL-2-1 harbors genes proposed to be involved in stress signaling, defense response mechanisms, and transcriptional regulation, among others. The qPCR results revealed that the majority of genes harbored by the qROL-2-1 recorded a higher transcript accumulation level in Milyang352 over time compared to 93-11. Another set of genes exhibited a high transcript abundance in P1 compared to P2, while a few were differentially regulated between both parents. Therefore, OsTCP7 and OsMYB21, OsARF8 genes encoding transcription factors (TFs), coupled with OsTRX, OsWBC8, and OsLRR2 are suggested to play important roles in the positive regulation of ROL in rice. However, the recorded differential expression of OsDEF7 and OsEXPA, and the decrease in OsNIP2, Oscb5, and OsPLIM2a TF expression between parental lines proposes them as being involved in the control of oxygen flux level in rice roots.

Throttling Growth Speed: Evaluation of aux1-7 Root Growth Profile by Combining D-Root system and Root Penetration Assay.

Directional root growth control is crucial for plant fitness. The degree of root growth deviation depends on several factors, whereby exogenous growth conditions have a profound impact. The perception of mechanical impedance by wild-type roots results in the modulation of root growth traits, and it is known that gravitropic stimulus influences distinct root movement patterns in concert with mechanoadaptation. Mutants with reduced shootward auxin transport are described as being numb towards mechanostimulus and gravistimulus, whereby different growth conditions on agar-supplemented medium have a profound effect on how much directional root growth and root movement patterns differ between wild types and mutants. To reduce the impact of unilateral mechanostimulus on roots grown along agar-supplemented medium, we compared the root movement of Col-0 and auxin resistant 1-7 in a root penetration assay to test how both lines adjust the growth patterns of evenly mechanostimulated roots. We combined the assay with the D-root system to reduce light-induced growth deviation. Moreover, the impact of sucrose supplementation in the growth medium was investigated because exogenous sugar enhances root growth deviation in the vertical direction. Overall, we observed a more regular growth pattern for Col-0 but evaluated a higher level of skewing of aux1-7 compared to the wild type than known from published data. Finally, the tracking of the growth rate of the gravistimulated roots revealed that Col-0 has a throttling elongation rate during the bending process, but aux1-7 does not.

Root allocation and foraging precision in heterogeneous soils

Root growth patterns respond to small-scale resource heterogeneity and the presence of roots of neighboring plants, but how a plant integrates its responses to these cues is not well understood. In the presence of neighbors, plants may shift allocation to roots as a consequence of plant size and root:shoot allometry, as a response to resource depletion by neighbors, or through a direct response to neighbor presence. The same response pathways also have the potential to alter proliferation in resource-rich patches in soil.Four species of grassland plants were grown in the greenhouse as single plants, monocultures, and mixtures. Root length allocation as a function of shoot mass was examined for background soil and fertilized patches. Plants grown with same-species neighbors followed the same allometric trajectory as single plants for root length in background soil, so any change in root allocation was due only to reduced plant size. Root proliferation in patches declined with neighbors, consistent with a response to resource depletion. Mixtures overproduced roots in both background soil and in patches, relative to plants of the same size in monocultures.

Naturally coloured roots as a tool for studying root interactions in mixed cropping

The objective of this study was to evaluate the usage of species with coloured roots to study root growth patterns during intercropping. Red beet (Beta vulgaris L. cv. Detroit), having clear red roots, was used in a semi-field and field experiment to allow identification and quantification of roots of the individual species in the mixture. In the field experiment, red beet was strip intercropped with lucerne (Medicago sativa L. cv. Creno) and kale (Brassica oleracea L. var. Sabellica), respectively while the red beet-lucerne intercropping was conducted in large rhizoboxes where root growth distribution and <sup>15</sup>N isotope uptake was determined. The study confirmed that the direct visual measurement of root growth using species with coloured roots and indirect tracer uptake measurements contributed to the success of studying root growth dynamics in intercropping systems. Red beet root intensity was not considerably affected by the strip intercropping when the crops were established at the same time, but when established between existing lucerne strips, a reduction in roots at the border row was shown. Lucerne and kale were both observed to be able to exploit the deep soil layers beneath the red beet border row.

Effects of gibberellic acid on the stem and root growth patterns of Abelmoschus esculentus

The seeds of Abelmoschus esculentus were grown in sandy loam soil of three field plots for the treatment of GA3 hormone concentration such as control plot (A), no treatment was given to this plot. Plot (B) was treated by GA3 (10-2 M) concentration and plot (C) was treated by GA3 (10-3 M) concentration daily and compared to the control field plot. The plants of Abelmoschus esculentus, for the growth analysis were taken regularly and randomly at the 15 days interval from the seedling emergence stage till to maturity. The length of Abelmoschus esculentus stem and root growth pattern (Okra) was observed with two concentrations of these plant hormones such as GA3 (10-2 M) and GA3 (10-3 M)) concentration and to evaluate the best concentration of these growth regulators as (GA3 (10-3 M)) only, which showed the maximum stem and root length of the Abelmoschus esculentus as compared to the control.