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The study was carried out to determine the root architectural characteristics of the one-year saplings of two species of boxwood (Buxus sempervirens L. and Buxus balearica Lam.), which are endangered and natural plants of Turkey, in the greenhouse environment using the WinRhizo root analysis program and scanner. Total root length (cm), root surface area (cm2), root volume (cm3), average root diameter (mm), number of tips, number of forks and number of root crossings were determined in the study. According to the results of the study, the increase in temperature and decrease in humidity values in the second year of both species were effective on the root architectural features. As a result of this effect, the second year root length (3810 cm), number of root tips (2299), number of forks (7007) and number of root crossings (696) increased, root diameter (1.4 mm), root surface area (2158 cm2) and root volume (8 cm3) decreased. As a result, it has been concluded that species can make changes in their root parameters to adapt to different conditions and their adaptability is high. In general, the best results in root architectural parameters were obtained from Buxus balearica on the basis of species.

A sufficient nitrogen (N) supply is pivotal for high grain yield and desired grain protein content in wheat (Triticum aestivum L.). Elucidation of physiological and molecular mechanisms underlying nitrogen use efficiency (NUE) will enhance our ability to develop new N-saving varieties in wheat. In this study, we analyzed two soft red winter wheat genotypes, VA08MAS-369 and VA07W-415, with contrasting NUE under limited N. Our previous study demonstrated that higher NUE in VA08MAS-369 resulted from accelerated senescence and N remobilization in flag leaves at low N. The present study revealed that VA08MAS-369 also exhibited higher nitrogen uptake efficiency (NUpE) than VA07W-415 under limited N. VA08MAS-369 consistently maintained root growth parameters such as maximum root depth, total root diameter, total root surface area, and total root volume under N limitation, relative to VA07W-415. Our time-course N content analysis indicated that VA08MAS-369 absorbed N more abundantly than VA07W-415 after the anthesis stage at low N. More efficient N uptake in VA08MAS-369 was associated with the increased expression of genes encoding a two-component high-affinity nitrate transport system, including four NRT2s and three NAR2s, in roots at low N. Altogether, these results demonstrate that VA08MAS-369 can absorb N efficiently even under limited N due to maintained root development and increased function of N uptake. The ability of VA08MAS-369 in N remobilization and uptake suggests that this genotype could be a valuable genetic material for the improvement of NUE in soft red winter wheat.

Grasses have a segmental morphology. Compared to leaf development, data on root development at the phytomer level are scarce. Leaf appearance interval was recorded over time to allow inference about the age of segmental sites that later form roots. Hydroponically grown Lolium perenne cv. Aberdart tillers were studied in both spring and autumn in increasing and decreasing day length conditions, respectively, and dissected to define the development status of roots of known age on successive phytomers basipetally on the tiller axis. Over a 90-day observation period spring and autumn tillers produced 10.4 and 18.1 root bearing phytomers (Pr), respectively. Four stages of root development were identified: (0) main axis elongation (~0–10 days), (1) primary branching (~10–18 days), (2) secondary branching (~18–25 days), and (3) tertiary and quaternary branching without further increase in root dry weight. The individual spring roots achieved significantly greater dry weight (35%) than autumn roots, and a mechanism for seasonal shift in substrate supply to roots is proposed. Our data define a root turnover pattern likely also occurring in field swards and provide insight for modelling the turnover of grass root systems for developing nutrient efficient or stress tolerant ryegrass swards.

Roots are the most important plant organ for absorbing essential elements, such as water and nutrients for living. To develop new climate-resilient soybean cultivars, it is essential to know the variation in root morphological traits (RMT) among diverse soybean for selecting superior root attribute genotypes. However, information on root morphological characteristics is poorly understood due to difficulty in root data collection and visualization. Thus, to overcome this problem in root research, we used a 2-dimensional (2D) root image in identifying RMT among diverse soybeans in this research. We assessed RMT in the vegetative growth stage (V2) of 372 soybean cultivars propagated in polyvinyl chloride pipes. The phenotypic investigation revealed significant variability among the 372 soybean cultivars for RMT. In particular, RMT such as the average diameter (AD), surface area (SA), link average length (LAL), and link average diameter (LAD) showed significant variability. On the contrary RMT, as with total length (TL) and link average branching angle (LABA), did not show differences. Furthermore, in the distribution analysis, normal distribution was observed for all RMT; at the same time, difference was observed in the distribution curve depending on individual RMT. Thus, based on overall RMT analysis values, the top 5% and bottom 5% ranked genotypes were selected. Furthermore, genotypes that showed most consistent for overall RMT have ranked accordingly. This ultimately helps to identify four genotypes (IT 16538, IT 199127, IT 165432, IT 165282) ranked in the highest 5%, whereas nine genotypes (IT 23305, IT 208266, IT 165208, IT 156289, IT 165405, IT 165019, IT 165839, IT 203565, IT 181034) ranked in the lowest 5% for RMT. Moreover, principal component analysis clustered cultivar 2, cultivar 160, and cultivar 274 into one group with high RMT values, and cultivar 335, cultivar 40, and cultivar 249 with low RMT values. The RMT correlation results revealed significantly positive TL and AD correlations with SA (r = 0.96) and LAD (r = 0.85), respectively. However, negative correlations (r = −0.43) were observed between TL and AD. Similarly, AD showed a negative correlation (r = −0.22) with SA. Thus, this result suggests that TL is a more vital factor than AD for determining SA compositions.

Adenophora triphylla var. japonica Hara is a highly valued medicinal plant that is used to treat or prevent bronchitis, cough, cancer, and obesity. However, there has been no study on the production of Adenophora triphylla var. japonica Hara seedlings in a closed-type plant production system (CPPS). This study was conducted to examine the growth characteristics of Adenophora triphylla var. japonica Hara seedlings as affected by different growing media. The seeds were sown on a 128-cell plug tray filled with urethane sponges (US), LC grow foam (LC), rockwool (RW), or terra-plugs (TP). The seedlings were cultured for a duration of 54 days under temperature 25 &plusmn, 1&deg, C, a photoperiod of 12/12 h (light/dark), and light intensity of 180 &micro, mol&middot, m&minus, 2&middot, s&minus, 1 photosynthetic photon flux density provided by RB LEDs (red:blue = 8:2) in a closed-type plant production system (CPPS). The germination rate of Adenophora triphylla var. japonica Hara was significantly highest in the TP. Also, seedling shoot growth indicators of plant height, leaf length, leaf width, number of leaves, fresh weight (FW), and dry weight (DW) of the shoot, and leaf area were markedly the greatest in the TP and the lowest in the US. The SPAD (soil-plant analysis development) value was higher in the TP and US than in the LC or RW. In addition, the seedling root growth characteristics of total root length, root surface area, root volume, and number of root tips were significantly greatest in the TP. Moreover, the maximum root diameter, FW and DW of roots were the greatest in the TP. In conclusion, the results suggest that TP are viable for the growth development of Adenophora triphylla var. japonica Hara seedlings.

This study was performed to identify the effect of mixed bed soil on growth of aerial parts and root zone of daughter plants for nursery field strawberry seedling raising with expanded chaff. The plant height and leaf area of daughter plants were highest or largest in the mixed soil of ERH +RH (100:0, v/v), followed by ERH+RH (75:25). The higher the mixing ratio of RH, the shorter the plant height or the smaller the leaf area. A similar tendency was observed in fresh weight. Within a root diameter of 0-0.4 mm and a root height range of 0.4-0.8 mm, root surface area and volume were statistically significantly better with treatment of ERH+RH (100:0, v/v) compared to those of roots treated with ERH+RH (75:25), ERH+RH (50:50) and ERH+RH (25:75). The growth rate of aerial parts and root zone of daughter plants were noticeably lower in two mixing ratios of 50:50 and 25:75. According to the mixing ratios of ERH+CD surface treatment, the number of roots was greatest in plants treated with ERH+CD (80:20, v/v) and ERH+CD (85:15) on August 1. However, the number of roots was highest in plants treated with ERH+CD (85:15, v/v) on August 15. Root length was longest in the plant with no treatment, and drastically shortened from ERH+CD (90:10, v/v) in both surface and mixed treatment. Although root weight showed a significant difference in ERH+CD (90:10, v/v) treatment, its increase was gradual. The rate of root growth was highest in ERH+CD (85:15). These study findings suggest that the content ratios of mixed soil ERH+RH (75:25, v/v) or below and ERH+CD (85:15) are thought to be desirable for the production of high quality seedlings.

Root hair growth dramatically expands the root surface area, thus facilitating water and nutrient uptake. Until recently, the molecular mechanism underlying root hair growth was unknown. Recent studies have revealed that the transcription factor ROOT HAIR DEFECTIVE 6 LIKE 4 (RSL4) coordinates hormonal, environmental, and developmental factors to trigger polar growth Fil: Marzol, Eliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Borassi, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Denita Juárez, Silvina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Mangano, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Estevez, Jose Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina

Fine root distribution was investigated in Pinus densiflora stands using soil core sampling and minirhizotrons, and conversion factors and regression equations were developed for converting minirhizotron data into fine root biomass. Fine root biomass was measured by soil core sampling from October, 2012 to September, 2013 once a month except for the winter, and surface area of fine roots was estimated by minirhizotrons from May to August, 2013 once a month. Fine root biomass and surface area were significantly higher in the upper soil layers than in the lower soil layers. Fine root biomass showed seasonal patterns; the mean fine root biomass (kg·ha �1 ) in summer (3,762.4) and spring (3,398.0) was significantly higher than that in autumn (2,551.6). Vertical and seasonal patterns of fine root biomass might be related to the soil bulk density, nutrient content and temperature with soil depth, and seasonal changes of soil and air temperature. Conversion factors (CF) between fine root surface area from minirhizotron data and fine root biomass from soil core sampling were developed for the three soil depths. Then a linear regression equation was developed between the predicted fine root biomass using CF and the measured fine root biomass (y = 79.7 + 0.93x, R 2 = 0.81). We

Manually measuring tree root characteristics can be inefficient and limiting. To test the application of a new digital technology in tree root architecture research, root systems from 29 green ash (Fraxinus pennsylvanica 'Patmore') trees were unearthed, cleaned, and photographed to create 3D models using structure from motion (SfM) photogrammetry. Three root segments from each root system were selected, marked, and removed after being photographed. The volumes of these segments (derived from the 3D models) were compared against volumes measured using water displacement. In addition to the root segments, model and water displacement volumes were compared for three complete root systems. Regression analysis showed a strong linear relation between the two volumes measurements (adjusted R2 = 0.97 for the root segment data). The RMSE for the root segment volume estimates was 40.37 cm3 (12.3%), with a bias of 17.2 cm3 (5.3%). This error rate was similar to previous published work and suggests the technology used may allow researchers to improve efficiency in data capture, add new measurements (i.e., surface area) to their modeling efforts, and digitally preserve tree root systems for future study.

Green leaves face two fundamental challenges (i.e., carbon fixation and stress tolerance) during their lifespan. However, the relationships between leaf production potential and leaf tolerance potential have not been explicitly tested with a broad range of plant species in the same environment. To do so, we conducted a field investigation based on 107 woody plants grown in a common garden and complementary laboratory measurements. The values, as measured by a chlorophyll meter, were significantly related to the direct measurements of chlorophyll content on a leaf area basis. Area-based chlorophyll content was positively correlated with root surface area, whole-plant biomass, leaf mass per area (LMA) and force to punch. Additionally, LMA had a positive correlation with force to punch. Shrubs had a higher leaf chlorophyll content than trees; however, shrubs and trees exhibited a similar leaf lifespan, force to punch and LMA. These findings suggest that the production potential of leaves and their tolerance to stresses may be convergent in woody species and that the leaf production potential may differ between shrubs and trees. This study highlights the possibility that functional convergence and divergence might be linked to long-term selection pressures and genetic constraints.

Drought-induced tree susceptibility is a major risk associated with climate change. Here we report how an 11-week drought affected tracheid structure, gene expression, and above- and belowground growth in 5-year-old Norway spruce trees (Picea abies) under controlled conditions. The canopy of trees subjected to severe drought had significantly less current-year needle biomass, and fewer tracheids and tracheid rows in current-year shoots compared to fully watered control trees. Belowground tissues were more strongly affected by drought than aboveground tissues. In fine roots (

DNA marker-assisted selection appears to be a promising strategy for improving rates of leaf photosynthesis in rice. The rate of leaf photosynthesis was significantly higher in a high-yielding indica variety, Habataki, than in the most popular Japanese variety, Koshihikari, at the full heading stage as a result of the higher level of leaf nitrogen at the same rate of application of nitrogen and the higher stomatal conductance even when the respective levels of leaf nitrogen were the same. The higher leaf nitrogen content of Habataki was caused by the greater accumulation of nitrogen by plants. The higher stomatal conductance of Habataki was caused by the higher hydraulic conductance. Using progeny populations and selected lines derived from a cross between Koshihikari and Habataki, it was possible to identify the genomic regions responsible for the rate of photosynthesis within a 2.1 Mb region between RM17459 and RM17552 and within a 1.2 Mb region between RM6999 and RM22529 on the long arm of chromosome 4 and on the short arm of chromosome 8, respectively. The designated region on chromosome 4 of Habataki was responsible for both the increase in the nitrogen content of leaves and hydraulic conductance in the plant by increasing the root surface area. The designated region on chromosome 8 of Habataki was responsible for the increase in hydraulic conductance by increasing the root hydraulic conductivity. The results suggest that it may be possible to improve photosynthesis in rice leaves by marker-assisted selection that focuses on these regions of chromosomes 4 and 8.

Electrical resistances of roots and stems of hydroponically raised willows (Salix schwerinii) were studied and related to root morphology. Willow cuttings with and without roots were set in a constant electric field (effective voltage of 0.1 V, sine-AC, 128 Hz) in a hydroponic solution. The electrical resistance of different components in the measurement system was measured and analysed in relation to root surface area in contact with the cultivation solution. Axial resistivities of single root segments and of stems were measured. The results showed that the resistance decreased in relation to an increase in the contact surface area of the roots with the solution. The resistance depended strongly on the contact area of the stem with the solution, however, thus causing bias in the evaluation of root surface area. This work is a new contribution for the understanding of current pathways in the root system as exposed to an external electric field and for developing a non-destructive method to study plant roots accordingly. It may be concluded that the electrical resistance method is a useful non-destructive method to study roots and their physiological properties. Electrical analogues for roots and stem comprising resistors are discussed in relation to in situ measurements.

We examined the permeability of roots of Dutch ‘Dundee’ and Japanese ‘Reiyo’ varieties of tomato seedlings to nutrient solutions and potassium ions. Seedlings were grown under 5 different conditions: (1) Seedlings were grown in Otsuka-A nutrient solution adjusted to an electric conductivity (EC) of 2.4 dS·m−1, and on the experiment day their roots were permeated with EC 2.4; (2) before the experiment day the EC was changed to 7.2 dS·m−1, and then roots were permeated with EC 7.2 in the experiment; (3) roots were permeated with potassium chloride (KCl) solution whose water potential was equivalent to EC 2.4 in the experiment; (4) before the experiment day the EC was changed to EC 7.2, and then roots were permeated with KCl solution whose water potential was equivalent to EC 7.2 in the experiment; and (5) roots were permeated with that KCl solution whose water potential was equivalent to EC 7.2 in the experiment. We measured the root permeability of seedlings grown in each solution, and the water potentials of exudates by using a pressure chamber and an isopiestic psychrometer. The nutrient solution or potassium solution in the chamber was forced into the plants under pressure. We then measured the quantity of extraction from the cutting surface of the root and root surface area to calculate root permeability. As a result, we found that, except in the KCl permeability experiment with a water potential equivalent to EC 2.4, the Japanese variety had greater permeability of nutrient solution and potassium. On this basis we conjectured that the Japanese variety ‘Reiyo’, whose root permeability was high, is able to assimilate more water and nutrients than the Dutch variety ‘Dundee’. On this basis we found that differences in root permeability can be considered one reason why ‘Reiyo’ grows larger than ‘Dundee’ in the initial part of its growth period.

Light and frequent (LF) and deep and infrequent (DI) irrigation are two common practices for golf course managers. Few studies have compared the effects of these two opposing irrigation practices on summer root performance in creeping bentgrass (Agrostis stolonifera L.). The objectives of this fi eld study were to quantify summer root development and longevity in response to LF vs. DI irrigation in ‘Providence’ creeping bentgrass grown on a sand-based rootzone. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, whereas DI plots were irrigated at leaf wilt to wet soil to a depth ≥24 cm. Root measurements were obtained using the minirhizotron imaging technique and included total root count, total root length (TRL), total root surface area (TRSA), and average root diameter. When averaged over the entire 0- to 24-cm rootzone depth, DI-irrigated creeping bentgrass produced a greater number of roots, longer root lengths, and a larger root surface area than LF-irrigated turf. Average root diameters were smaller in DI-irrigated creeping bentgrass in the summer of 2007. Compared with data collected in 2006, the 2-yr-old turf had 55 and 32% fewer roots in LF- and DI-irrigated bentgrass by September 2007, respectively. There were similar reductions in TRL and TRSA between years in both irrigation regimes. Deep and infrequent irrigation stimulated root growth throughout the 0- to 24-cm rootzone in May and June and promoted root longevity in summer.

To understand the physiological mechanism that confers Cd sensitivity, root morphology and Cd uptake kinetics of the Cd-sensitive mutant and wild type rice were investigated. The root length, root surface area, and root number of mutant rice decreased more significantly with increasing Cd concentration in growth media compared with the wild type rice. The uptake kinetics for 109Cd2+ in roots of both the mutant and wild type rice were characterized by a rapid linear phase during the first 6 h and a slower linear phase during the subsequent period. Concentration-dependent Cd2+ influx in both species could be characterized by the Michaelis-Menten equation, with similar apparent Km values for mutant and wild type rice (2.54 and 2.37 µM, respectively). However, the Vmax for Cd2+ influx in mutant root cells was nearly 2-fold higher than that for wild type rice, indicating that enhanced absorption into the root is one of the mechanisms involved in Cd sensitivity in mutant rice.

Trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] and paclobutrazol (PAC) [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-tri-azol-1-yl)pentan-3-ol] are routinely used to suppress clipping production. Single-leaf turfgrass C exchange rates (CERs) in response to plant growth regulator (PGR) treatment have not been characterized. Individual Kentucky bluegrass (KBG, Poa pratensis L.) plants received label rates of TE or PAC and were placed in growth chambers at 23/18 or 30/25°C. Photosynthetic efficiency and CER measurements were recorded every 4 d for 44 d. Total root length (TRL), root surface area (SA), and average root diameter were measured at the end of the study. Reductions in CERs of TE- or PAC-treated plants were short lived with CERs suppressed 17 to 29% of control (POC) at 4 and 12 days after treatment (DAT), respectively. Plants treated at 23/18°C with PGRs typically had short-lived increases in CERs following CER suppression. A similar pattern of CER response to PGR treatment was observed at the 30/25°C temperature regime. Quantum efficiency was unaffected, but plants treated with PGRs had reduced root growth. PAC caused the greatest reduction in TRL and SA while increasing root diameter. A decline in TRL and SA in conjunction with increased tillering indicates that PGR reduced TRL and SA on a tiller basis. Changes in single-leaf CERs do not fully explain PGR-induced changes in plant growth.

Elsholtzia argyi and Elsholtzia splendens, which are Chinese endemic Pb/Zn mined and Cu mined ecotype respectively, were investigated in the aspect of their response to Pb toxicity in the presence or absence of EDTA addition. After 8 d's Pb treatment, root length, root surface area and root volume of E. splendens decreased much more than those of E. argyi, and reduced considerably with increase of Pb, while no marked change was noted for root average diameter. Compared to E. argyi, length of root with diameter (D)0.2 mm was significantly reduced for E. splendens as Pb increasing. Root with cross-sectional area of D0.1 mm for E. splendens was at Pbor =10 mg/L, while for E. argyi, it was at Pbor =25 mg/L. DW of E. splendens decreased much more than that of E. argyi with increase of Pb. E. argyi exhibited much more tolerance to Pb toxicity than E. splendens. Treatment with 100 mg/L Pb plus 50 mmol/L EDTA significantly decreased the length and surface area of Dor =0.2 mm root, increased the length and surface area of 0.2or =Dor =0.8 mm root for the case of E. argyi, while for E. splendens, length and surface area of D0.6 mm root reduced, as compared to 100 mg/L Pb treatment, alone. At 100 mg/L Pb, shoot Pb accumulation in E. splendens and E. argyi were 27.9 and 89.0 microg/plant DW respectively, and much more Pb was uptaken by the root and translocated to the stem of E. argyi as compared to E. splendens. Treatment of the plant with 100 mg/L Pb plus 50 mmol/L EDTA increase leaf Pb accumulation from 16.8 to 84.9 g/plant for E.splendens and from 18.8 to 52.5 g/plant for E. argyi, while both root and stem Pb pronouncedly reduced for both Elsholtzia species. The increased translocation of Pb to the leaf of E. splendens than that of E. argyi at the treatment of 100 mg/L Pb plus 50 mmol/L EDTA should be further investigated.

The function and activity of a root system is closely linked to its normal environment, the soil. The soil volume exploited by the two species was calculated and a comparison showed that Calamus rotang exploited more soil volume than C. thwaitesii. The effective soil volume was also found to show an increase in C. rotang when compared to C. thwaitesii. Knowing the effective soil volume, the size of the polybag to be used in the nursery can be adjusted. The root spread of the two species shows that a 30 × 30 × 30 cm pit size will be sufficient for seedlings up to 2 years old. Rooting density is found to be more in the upper 30 cm layer of soil in both species. Root density, total root intensity and fine root intensity are higher in C. thwaitesii when compared to C. rotang. Root surface area also is more in C. thwaitesii. Hence, this species will be more efficient in water and nutrient uptake in the seedling stage. Both species are good soil binders.

International audience; The water absorption by terminal branch roots of mature oak, beech and spruce trees was measured in situ with miniature sap flow gauges for 11 consecutive days and related to the suberin and lignin content of the fine root periderm. All fine roots contained a well-developed periderm, whereas no primary white roots were present. Mean root water uptake decreased in the sequence beech - spruce - oak. Oak roots contained twice as much suberin and a thicker periderm than beech, and had smaller mean water uptake rates (201 vs. 508 g m-2 root surface d-1). However, spruce with 2 to 7 times smaller suberin contents had lower uptake rates (346 g m2 d-1) than beech with more suberin. We conclude that the relationship between periderm chemistry and water absorption is only weak in the three species. Other factors such as hydraulic resistances in the soil-root interface, or the size of water potential gradients may be more influential in regulating root water uptake.; Relation entre la composition chimique du périderme et le taux d'absorption d'eau, in situ, des petites racines de chêne, hêtre et épicéa. On a mesuré, in situ, avec des sondes miniaturisées de flux de sève, pendant 11 jours consécutifs, l'absorption d'eau par les extrêmités des racines de sujets adultes de chêne, hêtre et épicéa. Celle-ci a été ensuite mise en relation avec le contenu en subérine du périderme des petites racines. Toutes ces petites racines présentaient un périderme bien développé, sans racines primaires blanches. Les différentes espèces se classent pour le prélèvement d'eau moyen dans l'ordre décroissant suivant : hêtre, épicéa, chêne. Les racines de chêne contenaient deux fois plus de subérine et comportaient un périderme plus épais que le hêtre. Leur prélèvement d'eau était en moyenne plus faible (201 contre 508 g m-2 de surface racinaire et par jour). Cependant, l'épicéa, avec un contenu de subérine 2 à 7 fois inférieur, présentait un taux de prélèvement plus faible (346 g m2 et par jour) que le hêtre qui a pourtant plus de subérine. Nous en concluons que la relation entre la composition chimique du périderme et l'absorption d'eau n'est que faible pour les trois espèces. D'autres facteurs, tels que la résistance hydraulique à l'interface sol/racines, ou l'importance des gradients de potentiels hydriques, pourraient jouer un rôle plus important pour la régulation du prélèvement d'eau.

The ability of root systems to absorb water was determined as the root hydraulic conductance for five exotic genotypes (PI 416937, H2L16, N95‐SH‐259, PI 407859‐2, and PI 471938) and the commercial cultivar Young of soybean (Glycine max [L.] Merrill). The genotypes were grown for 28 d in flowing hydroponic culture to minimize possible variations in physical or chemical constraints on root development and functioning. Root hydraulic conductance was determined in response to applied hydrostatic pressure to the solution inside a pressure vessel to induce solution flow through the root system to the nonpressurized cut‐stem surface. Almost twofold differences in hydraulic conductance of from 0.43 to \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{...

In this paper we examine the key elements of cluster or proteoid roots, and trace their origins back to regular root properties. By viewing the root system as being composed of two categories of surface, the high transport capacity (HTC) area, just behind the meristem, and the low transport capacity (LTC) area (the rest of the root system), based on export and import capacities, we examine root system architecture in terms of structure–function relationships, and conclude that measuring total root exudation per unit area, volume or mass will not give useful comparative data for root transport properties. Furthermore, the cluster root represents a manipulation of the HTC to LTC root surface area ratio. Increased exudation and P uptake may be no higher in individual rootlets than in other HTC regions of the root system. We also examine the transformation theory (the theory of form resulting from a series of forces, which, when altered, lead to a change, or transformation in form) as an explanation of cluster root evolution, and conclude that the cluster root requires only a change in pericycle response to depleted internal nutrient levels, with the other characteristics representing consequences stemming from the form and constraints of the root system.

In two separate studies, the suckering of trembling aspen (Populus tremuloides Michx.) roots was assessed in response to different daily maximum soil temperatures and in relation to available nutrients (CaSO4 and NH4NO3). In the first study, aspen root sections were incubated under high:low temperature regimes of 12:8, 14:8, 16:8, 18:8, or 20:8°C until 124 degree-days above 8°C had been reached. Daily maximum temperature did not affect the number of suckers produced per square centimetre of root surface area or per root section. However, more time was required to initiate suckers on root sections grown under the 12:8°C temperature regime compared with those grown at 20:8°C. Furthermore, when calculated from a base temperature of 5°C, the number of degree-days needed to initiate aspen suckers was not different across the temperature regimes. In the second study, CaSO4, NH4NO3, or distilled water was added to aspen root sections. While nutrients did not affect the number of suckers produced, the addition of CaSO4 or NH4NO3 significantly increased sucker dry mass. Nutrient addition appeared to stimulate sucker growth and mobilization of stored reserves to support this growth.

A pond experiment was conducted to examine the influence of convective flow on root morphology of Typha domingensis plants grown in either sand, clay or a 50:50 mixture of the two sediments. The sediment types had different mean redox potentials; +14.6, −253 and −160 mV, respectively. To prevent convective flow in treatment plants, the leaves were pierced above the water surface twice weekly throughout the experimental period. Plants responded to both leaf piercing and sediment type but in different ways. The mean root length of intact plants was 11.5–30.5% greater than in pierced plants whilst the mean root surface area of intact plants was 39.8–54.8% greater than in pierced plants. In both cases, the greatest percentage difference was found in plants growing in sand. Other characteristics, including biomass and its allocation, responded to sediment type but not leaf piercing with plants growing more vigorously in clay. The morphology of the plants varied between the sediments. Based on the lacunal cross-sectional area, plants growing in clay had the greatest capacity for oxygen transport.

Summary We investigated 59 plant species from the Great Plains grasslands with the following objectives: (1) Determine the ability of individual plant species to: (a) redirect root surface area growth to patches with high N and P concentrations; and (b) alter their root:shoot ratio in response to a non-uniform distribution of soil N and P. (2) Determine how a patchy distribution of soil N and P within a plant's rooting zone affects biomass, total root surface area, N uptake, %N in plant tissue, and N uptake per unit of root surface area. Results showed a diversity of responses with some important common patterns. (1) Root responses (defined as total RSA, allocation of RSA, and R:S ratio) were twice as prevalent as whole plant responses (defined as total N uptake, %N in plant tissue, and plant biomass). (2) The percentage of species with the ability to allocate their RSA to nutrient rich patches was 9 times higher in forbs than in grasses, but there were proportionally more grasses than forbs that increased their R:S ratios in response to nutrient patchiness. (4) The proportions of late successional forbs that responded to nutrient patchiness was higher than that of mid successional ones, but the size of the response was substantially larger in the latter. (4) We found a very weak coupling between root plasticity and plant performance. (5) Our results tend to suggest that: (a) most plants have sufficient plasticity in root system development to track the scale of soil nutrient heterogeneity and thus show similar performance regardless of the degree of nutrient patchiness; and (b) the benefits of root plasticity may be more critical for subdominant species as a general adaptation to compete for soil nutrients in mixed plant communities regardless of the extent of soil nutrient heterogeneity. Wir haben 59 Pflanzenarten der Prarie in den Great Plains mit folgenden Zielen untersucht: (1) Feststellung der Fahigkeiten der einzelnen Pflanzenart in Bezug auf: (a) die Steuerung des Wurzelwachstums in den oberflachennahen Bodenschichten in Bereiche mit hohem N- and P-Gehalt; und (b) Veranderung des Verhaltnisses Wurzelmasse: Pflanzenmasse als Reaktion auf eine uneinheitliche Verteilung des N und P im Boden. (2) Festzustellen, wie die Verteilung der verschiedenen Zonen des N- und P-Gehaltes innerhalb der Wurzelzone einer Pflanze sich auf die Biomasse, die gesamte durchwurzelte Flache, die N-Aufnahme, den N-Gehalt (%) in der Pflanzenmembran und die N-Aufnahme pro Einheit der Wurzeloberflache auswirkt. Die Ergebnisse zeigten eine Vielfalt an Reaktionen mit einigen wichtigen allgemeinen Mustern. (1) Wurzelreaktionen (definiert als Total RSA, Lokalisierung der RSA und R:S ratio) waren doppelt so ausgepragt wie die Reaktionen der gesamten Pflanze (definiert als Gesamt N-Aufnahme, N-Gehalt (%) in der Pflanzenmembran und Biomasse der Pflanze). (2) Die Prozentzahl der Arten mit der Fahigkeit, ihre RSA in nahrstoffreiche Bodenzonen zu dirigieren war bei Blattpflanzen neunmal hoher als bei Grasern, aber es waren propotional mehr Graser als Blattpflanzen, die ihr R:S ratio als Reaktion auf die Nahrstoffverteilung veranderten. (3) Die Reaktion derjenigen Blattpflanzen, die sich erst spater ansiedeln war groser als die der Mittelansiedler, wobei die Anzahl der Reaktionen unter den letzteren uberwog. (4) Wir stellten eine sehr schwache Verknupfung zwischen Wurzelflexibilitat und der Leistung der Pflanze fest. (5) Unsere Ergebnisse lassen folgende Schlusse zu: (a) die meisten Pflanzen haben eine ausreichende Flexibilitat in ihrer Wurzelsystementwicklung um Nahrstoffuneinheitlichkeiten im Boden zu begegnen und zeigen deshalb unveranderte Leistungsfahigkeit unabhangig von der Nahrstoffverteilung; und (b) der Nutzen der Wurzelflexibilitat kann fur nichtdominante Arten entscheidender sein, da in gemischten Pflanzenpopulationen generell die einzelnen Arten in Konkurrenz um die Nahrstoff stehen unabhangig von der inhomogenen Nuhrstoffverteilung.

Arabidopsis thaliana root hairs grow longer and denser in response to low-phosphorus availability. In addition, plants with the root hair response acquire more phosphorus than mutants that have root hairs that do not respond to phosphorus limiting conditions. The purpose of this experiment was to determine the efficiency of root hairs in phosphorus acquisition at high- and low-phosphorus availability. Root hair growth, root growth, root respiration, plant phosphorus uptake, and plant phosphorus content of 3-wk-old wild-type Arabidopsis (WS) were compared to two root hair mutants (rhd6 and rhd2) under high (54 mmol/m) and low (0.4 mmol/m) phosphorus availability. A cost-benefit analysis was constructed from the measurements to determine root hair efficiency. Under high-phosphorus availability, root hairs did not have an effect on any of the parameters measured. Under low-phosphorus availability, wild-type Arabidopsis had greater total root surface area, shoot biomass, phosphorus per root length, and specific phosphorus uptake. The cost-benefit analysis shows that under low phosphorus, wild-type roots acquire more phosphorus for every unit of carbon respired or unit of phosphorus invested into the roots than the mutants. We conclude that the response of root hairs to low-phosphorus availability is an efficient strategy for phosphorus acquisition.

Genotypic differences in nutrient acquisition are important determinants of nutrient efficiency. These differences can be related to root size and morphology and/or to root physiology. Root surface area can be enhanced through mycorrhizal associations. Root processes can affect rhizosphere pH and redox potential. In addition, root exudates affect rhizosphere chemistry. Exudation may be responsive to a particular nutrient deficiency. For example, P deficiency can induce the release of organic acids and/or acid phosphatases, and iron or Zn deficiencies result in the release of phytosiderophores by some species. Thus, in light of the diverse plant responses to nutrient-deficient soils, it will be necessary to identify the key mechanism(s) of tolerance in a particular field environment before initiating mass screening for a specific tolerance mechanism.

Sapwood cross-sectional area per unit leaf area (SA:LA) is an influential trait that plants coordinate with physical environment and with other traits. We develop theory for SA:LA and also for root surface area per leaf area (RA:LA) on the premise that plants maximizing the surplus of revenue over costs should have competitive advantage. SA:LA is predicted to increase in water-relations environments that reduce photosynthetic revenue, including low soil water potential, high water vapor pressure deficit (VPD), and low atmospheric CO(2). Because sapwood has costs, SA:LA adjustment does not completely offset difficult water relations. Where sapwood costs are large, as in tall plants, optimal SA:LA may actually decline with (say) high VPD. Large soil-to-root resistance caps the benefits that can be obtained from increasing SA:LA. Where a plant can adjust water-absorbing surface area of root per leaf area (RA:LA) as well as SA:LA, optimal RA:SA is not affected by VPD, CO(2) or plant height. If selection favours increased height more so than increased revenue-minus-cost, then height is predicted to rise substantially under improved water-relations environments such as high-CO(2) atmospheres. Evolutionary-attractor theory for SA:LA and RA:LA complements models that take whole-plant conductivity per leaf area as a parameter.

Growth and physiological responses before and after transplanting to a simulated landscape were studied for `East Palatka' holly (Ilex ×attenuata Ashe `East Palatka') grown in plastic containers (PC), in the ground in fabric containers (FC), or in the ground conventionally. At the end of a 15-month production period, trees grown in PC had more shoot dry weight and leaf area than trees grown in FC, and they had thinner trunks than field-grown trees. Root balls on harvested field-grown trees contained 55% and those grown in FC 65% of total-tree root surface area. Trees transplanted from FC had the lowest predawn leaf xylem potential and required more frequent post-transplant irrigation than trees grown in PC or in the ground. Carbon assimilation rate and stomata1 conductance in the first week after transplanting were highest for trees planted from PC. Dry weight of regenerated roots was similar for all production methods 4 months after transplanting from the nursery, but trees grown in PC had SO% more regenerated root length, and the roots extended further into the back-fill soil.

Growth and physiological characteristics were evaluated in autografted and reciprocally grafted plants of Prunus avium L. ×pseudocerasus Lindl. `Colt' and Prunus cerasus L. `Meteor'. Containerized plants were grown for 150 days in a greenhouse under either well-watered or water-stressed conditions. Both the scion and rootstock influenced growth (relative growth rate, R̄), morphological [leaf area : root surface area (LARSA) and specific leaf area (SLA)], and physiological (mean net assimilation rate, Ē) characteristics of grafted plants. Regardless of the watering regime, plants with `Meteor' scions and `Colt' rootstocks maintained higher R̄ than plants with `Colt' scions and `Meteor' rootstocks. This enhanced growth occurred as a result of higher Ē. Measurements on water-stressed plants also showed that the graft combination of `Meteor' on `Colt' had the lowest LARSA, while the reciprocal combination of `Colt' on `Meteor' had the highest. Differences in LARSA among water-stressed plants primarily reflected changes in SLA, as influenced by both rootstock and scion, and not in partitioning of dry weight between these organs.

Although many scientists have emphasized the importance of collecting quantitative data on various root traits relevant to crop performance, such data are lacking except for those on root length. Russell and Sanderson (1967) and Nye and Tinker (1969) discussed the relative importance of traits such as length, surface area, and volume of roots. However, due to the shortage of information, especially on root diameter, surface area, and volume, no definite conclusion has been reached hitherto.

Com o objetivo de estimar os parâmetros genéticos relativos às qualidades do sistema radicular de candeia, foram utilizadas mudas provenientes de 24 progênies de polinização livre do Parque Estadual Quedas do Rio Bonito em Lavras, MG. Dois meses após a germinação, as imagens das raízes de nove mudas de cada progênie, distribuídas em três classes de tamanho (grande, maiores mudas dentro de cada progênie, médio, mudas médias dentro da progênie e pequeno, mudas em torno de 5 cm), foram obtidas por scanner óptico. Posteriormente, as mesmas raízes foram coradas com corante azul de astra 0,1%, durante 15 min, e novamente analisadas. As leituras indicaram diferenças significativas entre material não-corado e corado, enfatizando o seu uso. Na análise de variância, houve diferenças significativas entre as progênies e entre os tamanhos analisados quanto aos caracteres de raízes: comprimento total, área da superfície, diâmetro médio e número de raízes finas. Os ganhos genéticos esperados com a seleção evidenciaram que esses caracteres devem ser estudados nas mudas grandes, pois apresentam os maiores valores esperados. Seedlings derived from 24 open-pollinated progenies from Quedas do Rio Bonito State Park, Lavras, MG, were used to estimate the genetic parameters concerning the quality of candeia root system. Two months after germination, optical scanning images of new seedling roots were obtained for each progeny, distributed into three size classes (large, medium and small). These roots were stained with 0.1% astra blue for 15 min and then analyzed. The results showed significant differences between stained and non-stained root samples indicating the need for root staining before the analysis. The analysis of variance also showed significant differences among progenies and size classes, which were analyzed considering the following traits: total root length, root surface area, mean diameter and the number of fine roots. The expected genetic gain with selection showed that these traits must be studied in grown seedlings as they showed the largest expected gains.

A distribuição da biomassa e da área absorvente do sistema radicular da pupunheira (Bactris gasipaes)foram estudadas num latossolo amarelo, textura argilosa, perto de Manaus, Amazonas, Brasil. Aproximadamente 80% da biomassa se encontrava no horizonte Ap, da qual 90% se encontrava dentro da área de projeção da copa. A biomassa total estimada pesou 72 kg, excluindo-se a massa logo abaixo do estipe. A área superficial das raízes aumentou significativamente conforme se afastava do estipe, devido a proporção cada vez maior de raízes terciárias e quartenárias, embora sua abundância por m3 diminuiu de forma similar à biomassa. A área superficial total estimada chegou a 545 m2, da qual se supõe que 50% é ativa na absorção de nutrientes. Supõe-se ainda que existam raízes absorventes até 8-9 m do estipe das plantas. Recomenda-se que a adubação seja feita dentro e logo fora da projeção da copa. The distribution of the pejibaye's (Bactris gasipaes)root biomass and absorbtive area was studied in a clay textured, yellow Oxisol, near Manaus, Amazonas, Brazil. Approximately 80% of the biomass was found in the Ap horizon and 90% of this within the crown projection area. Total biomass was estimated at 72 kg, without, however, including the very large mass immediately below the stem. The root surface area increased significantly as distance from the stem increased, due to the increase in the proportion of third and fourth order roots, although its abundance per m3 diminished like that of the biomass. The total root surface area was estimated at 545 m2, of which 50% is probably active in nutrient absorbtion. The observed distribution suggested that there are absorbtive roots at least 8-9 m from the stem. Fertilizer placement should be within and just outside of the crown projection area.", 'en

Several reports have suggested that inoculation of cereal plants with different species of the beneficial rhizosphere bacterium Azospirillum results in an enhanced plant growth (Levanony et al. 1989). The underlying mechanism by which Azospirillum affects plant growth are poorly understood. One mode of action could be linked to an enhancement of mineral uptake by the root system (Pacovsky 1990) and of root surface area (Levanony et al. 1989), although quantitative data are scanty. This communication provides evidence that A.brasilense promotes root and root hair growth along with the uptake of NO3 -, and enhances Fe++ accumulation in plant tissues.

Using area profile integration software and an image processing system, we reliably estimated total root surface area of intact each [Prunus persica (L.) Batsch.] seedlings by 1) producing high-quality monochromatic video images under preset and constant conditions; 2) determining a threshold gray intensity value that differentiates the finest roots on the image; 3) producing a binary image where all pixels with gray values above the threshold are black; 4) determining the proportion of black pixels on the 480× 512-pixel matrix; and 5) multiplying this two-dimensional root surface value by π to estimate total root surface area. Normalized intensity (an average intensity weighted according to the proportion of the binary image in each gray scale class) was calculated using software that superimposed the video image on the binary image and was used to estimate mean root diameter. Evidence of reliability and examples of the use of both estimates are provided.

Root and leaf growth of the arctic sedge Eriophorum vaginatum L. were studied from early spring (June 7) to early fall (August 7) in the foothills of the Brooks Range in northern Alaska. The observations were designed to test the hypothesis that root and leaf growth occur at similar rates. The results confirmed this hypothesis. The root/leaf biomass ratio remained constant over the growing season. Thus, root biomass can be estimated based on harvested leaf biomass. It was also shown that root and leaf surface areas can be calculated from the respective biomass values. However, changes in the specific weights of leaves and roots over the growing season would affect the accuracy of root biomass or root surface area predictions.

The paper describes the construction and the theory underlying a simple electrical analogue which may be used to simulate the internal oxygen relations of roots in the wetland condition. The model represents an unbranched root lying within an oxygen sink and consists of twenty circuit units linked in series. Each unit which can be programmed independently, represents the major oxygen diffusion paths, impedances and sinks recognizable in a centimetre-long segment of root/wet soil system. Simplicity has been achieved by specifying constant radius for the root (0.05 cm), constant potential activity for the external sink, by expressing respiration and radial oxygen loss as a function of root surface area, and by the non-inclusion of oxygen storage capacity.

SUMMARY Relative conductivity (K) to water in healthy apple trees ranged from maximum values of 18.2 cm3.100 s-1.cm length.0.001 Pas.kPa-1.cm-2 xylem area, for major suberized roots to values of 1.6 for 1-yr-old twigs. The values for equivalent parts of healthy cherry trees were 26.3 and 3.3. Trees with roots affected by the larvae of the fruit tree root weevil (Leptopius squalidus) which causes either chronic growth decline or sudden wilting and death, had values as low as 1% of healthy trees, in those parts of the tree showing wilting and lack of growth. Water flow under pressure into the root systems of healthy apple trees increased linearly with increases in pressure from 200 to 800 kPa. Flows into dormant and active root systems respectively were 0.6 and 1.7 cm3.100 s-1. 100 cm2 root surface area. 100 kPa-1.

The root systems of all plants adapt to soil conditions. One of the ways Norway spruce adapts is a regulation of absorbing root surface area, which can be viewed as an ecomorphological index of soil conditions. Minimal specific root surface area of absorbing roots of Norway spruce (28–29 m2kg−1) responds to optimal soil conditions. This was achieved at a soil bulk density of about 1.2 gcm−3.

Accumulation of Cd in the shoots of plants grown on Cd contaminated soils shows considerable variation. A previous preliminary experiment established that one major reason for this variation was the rate of Cd influx into the roots (mol Cd cm−2 root s−1). However, this experiment did not distinguish between solubilization of soil Cd on the one hand and difference in Cd uptake kinetics on the other. The main objectives of the present study were thus to characterize Cd uptake kinetics of plants continuously exposed to Cd concentrations similar to those encountered in soils. Furthermore we determined the factors responsible for differences in shoot Cd concentration such as net Cd influx, root area-shoot dry weight ratio, shoot growth rate and proportion of Cd translocated to the shoot. Maize, sunflower, flax and spinach were grown in nutrient solution with five constant Cd concentrations varying from 0 to 1.0 μmol L−1. Root and shoot parameters as well as Cd uptake were determined at two harvest dates and from these data Cd net influx and shoot growth rates were calculated. Cadmium uptake kinetics, i.e. the net Cd influx vs. Cd solution concentration followed a straight line. Its slope is the root absorbing power, α, $$ \left( {\alpha ={{{\mathrm{Cd}\;\mathrm{net}\;\mathrm{influx}}} \left/ {{\mathrm{Cd}\;\mathrm{solution}\;\mathrm{concentration}}} \right.}} \right) $$ . The α values of spinach and flax were about double that of maize and sunflower (5 × 10−6 cm s−1 vs. 2.5 × 10−6 cm s−1). Spinach and flax had a 3–5 times higher shoot Cd concentration than maize and sunflower. The difference in shoot Cd concentration was partly due to the higher Cd influx but also to a higher translocation of Cd from root to shoot and also to a slower shoot growth rate.

Nine rice varieties including three root types (I, II and III) were grown in both a nursery and a paddy field without transplanting. From both conditions samples were taken at their yellow maturation stages, in order to determine root ferrous coatings. The determinations were made by the o-phenanthroline method, after coatings were washed away by boiling the roots in IN-HCl for 45 minutes. From these experiments, it was found that the varieties belonging to the type I, of which root weight were larger than those of type II and III, were apt to have larger coatings per both plant and root (Fig. 1 & 2). As to ferrous coatings per unit surface area, it was nearly the same as those above mentioned (Fig. 3). Root surface area was calculated from root weight by such a formulae as A≒√^3(W proposed by the authors, in which A is the surface area and W is the weight per root. In addition to these experiments, seasonal changes of ferrous coatings were determined every 16 days after sowing, using three varieties of each root type. From these, it was found that, (1) ferrous coatings per unit surface area showed their maximum 44-60 days after seeding respectively according to varieties and then are gradually reduced till the period from heading to maturation (Fig. 6) and (2) those per plant and per root increased with the growth up to the maximum found at heading time (Fig. 4 & 5). These changes in coatings were also contrasted with the changes in the relative growth rates calculated by root weight increase. Maximum values in coatings were always observed at the periods when the growth rate dropped, that is, when the root activity lowered (Fig. 4, 5, 6 & 7).