共查询到20条相似文献,搜索用时 15 毫秒
1.
Zuzana Vatehová Karin Kollárová Ivan Zelko Danica Richterová-Kučerová Marek Bujdoš Desana Lišková 《Biologia》2012,67(3):498-504
The objective of this study was to determine the effect of silicon (Si) and cadmium (Cd) on root and shoot growth and Cd uptake
in two hydroponically cultivated Brassica species (B. juncea (L.) Czern. cv. Vitasso and B. napus L. cv. Atlantic). Both species are potentially usable for phytoextraction. Inhibitory effects of Cd on root elongation were
diminished by the impact of Si. Primary roots elongation in the presence of Cd + Si compared with Cd was stronger and the
number of lateral roots was lower in B. juncea than in B. napus. Cd content per plant was higher in B. napus roots and shoots compared with B. juncea. Suberin lamellae were formed closer to the root apex in Cd + Si than in Cd treated plants and this effect was stronger in
B. napus than in B. juncea. Accelerated maturation of endodermis was associated with reduced Cd uptake. Cd decreased the content of chlorophylls and
carotenoids in both species, but Si addition positively influenced the content of photosynthetic pigments which was higher
in B. napus than in B. juncea. Si enhanced more substantially translocation of Cd into the shoot of B. napus than of B. juncea. Based on our results B. napus seems to be more suitable for Cd phytoextraction than B. juncea because these plants produce more biomass and accumulate
higher amount of Cd. The protective effect of Si on Cd treated Brassica plants could be attributed to more extensive development of suberin lamellae in endodermis. 相似文献
2.
Root distribution and interactions between intercropped species 总被引:28,自引:0,他引:28
Even though ecologists and agronomists have considered the spatial root distribution of plants to be important for interspecific
interactions in natural and agricultural ecosystems, few experimental studies have quantified patterns of root distribution
dynamics and their impacts on interspecific interactions. A field experiment was conducted to investigate the relationship
between root distribution and interspecific interactions between intercropped plants. Roots were sampled twice by auger and
twice by the monolith method in wheat (Triticum aestivum L.)/maize (Zea mays L.) and faba bean (Vicia faba L.)/maize intercropping and in sole wheat, maize, and faba bean up to 100 cm depth in the soil profile. The results showed
that the roots of intercropped wheat spread under maize plants, and had much greater root length density (RLD) at all soil
depths than sole wheat. The roots of maize intercropped with wheat were limited laterally, but had a greater RLD than sole-cropped
maize. The RLD of maize intercropped with faba bean at different soil depths was influenced by intercropping to a smaller
extent compared to maize intercropped with wheat. Faba bean had a relatively shallow root distribution, and the roots of intercropped
maize spread underneath them. The results support the hypotheses that the overyielding of species showing benefit in the asymmetric
interspecific facilitation results from greater lateral deployment of roots and increased RLD, and that compatibility of the
spatial root distribution of intercropped species contributes to symmetric interspecific facilitation in the faba bean/maize
intercropping.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
3.
Hao Sun Yaoke Duan Namiki Mitani-Ueno Jing Che Jianhua Jia Jiaqi Liu Jia Guo Jian Feng Ma Haijun Gong 《Plant, cell & environment》2020,43(3):732-744
Silicon (Si) accumulation in shoots differs greatly with plant species, but the molecular mechanisms for this interspecific difference are unknown. Here, we isolated homologous genes of rice Si influx (SlLsi1) and efflux (SlLsi2) transporter genes in tomato (Solanum lycopersicum L.) and functionally characterized these genes. SlLsi1 showed transport activity for Si when expressed in both rice lsi1 mutant and Xenopus laevis oocytes. SlLsi1 was constitutively expressed in the roots. Immunostaining showed that SlLsi1 was localized at the plasma membrane of both root tip and basal region without polarity. Furthermore, overexpression of SlLsi1 in tomato increased Si concentration in the roots and root cell sap but did not alter the Si concentration in the shoots. By contrast, two Lsi2-like proteins did not show efflux transport activity for Si in Xenopus oocytes. However, when functional CsLsi2 from cucumber was expressed in tomato, the Si uptake was significantly increased, resulting in higher Si accumulation in the leaves and enhanced tolerance of the leaves to water deficit and high temperature. Our results suggest that the low Si accumulation in tomato is attributed to the lack of functional Si efflux transporter Lsi2 required for active Si uptake although SlLsi1 is functional. 相似文献
4.
Spatial and temporal patterns of root distribution in developing stands of four woody crop species grown with drip irrigation and fertilization 总被引:5,自引:0,他引:5
Mark Coleman 《Plant and Soil》2007,299(1-2):195-213
In forest trees, roots mediate such significant carbon fluxes as primary production and soil CO2 efflux. Despite the central role of roots in these critical processes, information on root distribution during stand establishment
is limited, yet must be described to accurately predict how various forest types, which are growing with a range of resource
limitations, might respond to environmental change. This study reports root length density and biomass development in young
stands of eastern cottonwood (Populus deltoidies Bartr.) and American sycamore (Platanus occidentalis L.) that have narrow, high resource site requirements, and compares them with sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.), which have more robust site requirements. Fine roots (<1 mm), medium roots (1 to 5 mm) and coarse roots (>5 mm) were
sampled to determine spatial distribution in response to fertilizer and irrigation treatments delivered through drip irrigation
tubes. Root length density and biomass were predominately controlled by stand development, depth and proximity to drip tubes.
After accounting for this spatial and temporal variation, there was a significant increase in RLD with fertilization and irrigation
for all genotypes. The response to fertilization was greater than that of irrigation. Both fine and coarse roots responded
positively to resources delivered through the drip tube, indicating a whole-root-system response to resource enrichment and
not just a feeder root response. The plastic response to drip tube water and nutrient enrichment demonstrate the capability
of root systems to respond to supply heterogeneity by increasing acquisition surface. Fine-root biomass, root density and
specific root length were greater for broadleaved species than pine. Roots of all genotypes explored the rooting volume within
2 years, but this occurred faster and to higher root length densities in broadleaved species, indicating they had greater
initial opportunity for resource acquisition than pine. Sweetgum’s root characteristics and its response to resource availability
were similar to the other broadleaved species, despite its functional resemblance to pine regarding robust site requirements.
It was concluded that genotypes, irrigation and fertilization significantly influenced tree root system development, which
varied spatially in response to resource-supply heterogeneity created by drip tubes. Knowledge of spatial and temporal patterns
of root distribution in these stands will be used to interpret nutrient acquisition and soil respiration measurements.
The US Government has the right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper.
Mention of a commercial or proprietary product does not constitute endorsement or recommendation by the USDA Forest Service. 相似文献
5.
Root tensile strength and root distribution of typical Mediterranean plant species and their contribution to soil shear strength 总被引:13,自引:0,他引:13
S. De Baets J. Poesen B. Reubens K. Wemans J. De Baerdemaeker B. Muys 《Plant and Soil》2008,305(1-2):207-226
In Mediterranean environments, gully erosion is responsible for large soil losses. It has since long been recognized that
slopes under vegetation are much more resistant to soil erosion processes compared to bare soils and improve slope stability.
Planting or preserving vegetation in areas vulnerable to erosion is therefore considered to be a very effective soil erosion
control measure. Re-vegetation strategies for erosion control rely in most cases on the effects of the above-ground biomass
in reducing water erosion rates, whereas the role of the below-ground biomass is often neglected or underestimated. While
the above-ground biomass can temporally disappear in semi-arid environments, roots may still be present underground and play
an important role in protecting the topsoil from being eroded. In order to evaluate the potential of plant species growing
in Mediterranean environments to prevent shallow mass movements on gully or terrace walls, the root reinforcement effect of
25 typical Mediterranean matorral species (i.e. shrubs, grasses herbs, small trees) was assessed, using the simple perpendicular
model of Wu et al. (Can Geotech J 16:19–33, 1979). As little information is available on Mediterranean plant root characteristics,
root distribution data were collected in SE-Spain and root tensile strength tests were conducted in the laboratory. The power
root tensile strength–root diameter relationships depend on plant species. The results show that the shrubs Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. have the strongest roots, followed by the grass Brachypodium retusum (Pers.) Beauv. The shrubs Nerium oleander L. and the grass Avenula bromoides (Gouan) H. Scholz have the weakest roots in tension. Root area ratio for the 0–0.1 m topsoil ranges from 0.08% for the grass
Piptatherum miliaceum (L.) Coss to 0.8% for the tree Tamarix canariensis Willd. The rush Juncus acutus L. provides the maximum soil reinforcement to the topsoil by its roots (i.e. 304 kPa). Grasses also increase soil shear strength
significantly (up to 244 kPa in the 0–0.1 m topsoil for Brachypodium retusum (Pers.) Beauv.). The shrubs Retama sphaerocarpa (L.) Boiss. and Anthyllis cytisoides L. are increasing soil shear strength to a large extent as well (up to 134 and 160 kPa respectively in the 0–0.10 m topsoil).
Whereas grasses and the rush Juncus acutus L. increase soil shear strength in the topsoil (0–0.10 m) to a large extent, the shrubs Anthyllis cytisoides (L.), Retama sphaerocarpa (L.) Boiss., Salsola genistoides Juss. Ex Poir. and Atriplex halimus L. strongly reinforce the soil to a greater depth (0–0.5 m). As other studies reported that Wu’s model overestimates root
cohesion values, reported root cohesion values in this study are maximum values. Nevertheless, the calculated cohesion values
are used to rank species according to their potential to reinforce the soil. 相似文献
6.
Gian Battista Bischetti Enrico A. Chiaradia Tommaso Simonato Barbara Speziali Barbara Vitali Paolo Vullo Antonio Zocco 《Plant and Soil》2005,278(1-2):11-22
Forest vegetation is known to increase hillslope stability by reinforcing soil shear resistance and by influencing hydrologic
conditions of soil. Although the importance of plant root systems for hillslope stability has received considerable attention
in recent years, the quantification of such an effect needs more investigation. In this paper, we present a synthesis of the
data gathered in the last 5 years for some species in different locations of the Alps and Prealps of Lombardy (Northern Italy)
with the aim to increase our knowledge on root tensile strength and on Root Area Ratio distribution within the soil. Concerning
root tensile strength we developed tensile strength–diameter relationships for eight species: green alder (Alnus viridis(Chaix) D.C.), beech (Fagus sylvatica L.), red willow (Salix purpurea L.), goat willow (Salix caprea L.), hazel (Corylus avellana L.), European ash (Fraxinus excelsior L.), Norway spruce (Picea abies (L.) Karst.) and European larch (Larix decidua Mill.). Results show a great variability among the different species and also for the same species. In general, however,
root strength (in terms of tension) tends to decrease with diameter according to a power law, as observed by other Authors.
Comparing the power law fitting curves for the considered species, it can be observed that they fall in a relatively narrow
band, with the exception of hazel, which appears the most resistant. Concerning the evaluation of root distribution within
the soil we estimated the Root Area Ratio (the ratio between the area occupied by roots in a unit area of soil) according
to its depth for five species (beech, Norway spruce, European larch, mixed hazel and ash) in three locations of Lombardy.
Results show that there is a great variability of root density for the same species well as for different points at the same
locality. The general behaviour of root density, in any case, is to decrease with depth according to a gamma function for
all the studied species. The results presented in this paper contribute to expanding the knowledge on root resistance behaviour
and on root density distribution within the soil. The studied location have allowed the implementation of soil–root reinforcement
models and the evaluation of the vegetation contribution to soil stability. 相似文献
7.
Localized alteration in lateral root development in roots colonized by an arbuscular mycorrhizal fungus 总被引:1,自引:0,他引:1
The morphological responses of root systems to localized colonization by endophytes is not well understood. We examined the
responses of lateral roots to the arbuscular mycorrhizal (AM) fungus Gigaspora margarita Becker & Hall inoculated locally into the soil. Peanut (Arachis hypogaea L.) and pigeon pea (Cajanus cajan (L.) Millsp.) were examined. Root boxes filled with nutrient-poor soil in were inoculated in one half with the fungus and
in the other half with a sterilized inoculum. Responses were apparent after 30 days but not after 20 days. Overall, lateral
root development was more advanced in inoculated soil. This was clearly observed for 2nd- and 3rd-order lateral roots, but
less clear for 1st-order lateral roots in both species, although percentage of colonized root length was higher in 1st-order
lateral roots. Whilst in peanut the responses were clearly evident at the level of lateral roots initiated on more proximal
parts of the tap root axis, they occurred on more distal parts in pigeon pea. We conclude that plants under nutrient-poor
conditions give priority to mycorrhizal roots when partitioning assimilation products within the root system. Thus, AM formation
may induce local morphological alteration of root systems.
Accepted: 29 August 1996 相似文献
8.
Perennial pastures are needed in farming systems in southern Australia to combat environmental problems such as dryland salinity. The mediterranean climate in southern Australia imposes constraints to the growth and survival of perennial plants. The aim of this study was to compare growth rates, resource allocation and root distribution in three perennial legumes, Medicago sativa L., Dorycnium hirsutum (L.) Ser. and Dorycnium rectum (L.) Ser., to identify different plant traits and their ecological and agronomic significance. Plants were grown in 1-m deep split tubes and destructive harvests were made every 2 weeks after plant emergence for 10 weeks. Leaf area and leaf, stem and root fresh and dry weights were measured. Maximum root depth and the root distribution were also determined. Seedlings of Dorycnium were slower to emerge and had a lower relative growth rate (RGR) than M. sativa. The slower RGR was associated with a lower specific leaf area (SLA) in D. hirsutum and a lower net assimilation rate (NAR) in D. rectum. Although all species allocated a similar proportion of biomass to roots, D. rectum had a shallower root distribution and took longer to produce deep roots. The slow growth rates of Dorycnium seedlings suggest that they are more prone to establishment problems due to competition from weeds or other pastures, and because they have less access to water at greater depth during summer drought. However, D. hirsutum displayed characteristics of a plant that is adapted to stressful environments and therefore may be able to grow in conditions where other perennial legumes cannot. 相似文献
9.
Fine root responses to temporal nutrient heterogeneity and competition in seedlings of two tree species with different rooting strategies 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Ecology and evolution》网站下载免费的PDF全文](/ch/ext_images/free.gif)
There is little direct evidence for effects of soil heterogeneity and root plasticity on the competitive interactions among plants. In this study, we experimentally examined the impacts of temporal nutrient heterogeneity on root growth and interactions between two plant species with very different rooting strategies: Liquidambar styraciflua (sweet gum), which shows high root plasticity in response to soil nutrient heterogeneity, and Pinus taeda (loblolly pine), a species with less plastic roots. Seedlings of the two species were grown in sandboxes in inter‐ and intraspecific combinations. Nutrients were applied in a patch either in a stable (slow‐release) or in a variable (pulse) manner. Plant aboveground biomass, fine root mass, root allocation between nutrient patch and outside the patch, and root vertical distribution were measured. L. styraciflua grew more aboveground (40% and 27% in stable and variable nutrient treatment, respectively) and fine roots (41% and 8% in stable and variable nutrient treatment, respectively) when competing with P. taeda than when competing with a conspecific individual, but the growth of P. taeda was not changed by competition from L. styraciflua. Temporal variation in patch nutrient level had little effect on the species’ competitive interactions. The more flexible L. styraciflua changed its vertical distribution of fine roots in response to competition from P. taeda, growing more roots in deeper soil layers compared to its roots in conspecific competition, leading to niche differentiation between the species, while the fine root distribution of P. taeda remained unchanged across all treatments. Synthesis. L. styraciflua showed greater flexibility in root growth by changing its root vertical distribution and occupying space of not occupied by P. taeda. This flexibility gave L. styraciflua an advantage in interspecific competition. 相似文献
10.
Root characteristics of representative Mediterranean plant species and their erosion-reducing potential during concentrated runoff 总被引:7,自引:1,他引:6
Gully erosion is an important soil degradation process in Mediterranean environments. Revegetation strategies for erosion
control rely in most cases on the effects of the above-ground biomass on reducing water erosion rates, whereas the role of
the below-ground biomass is often neglected. In a Mediterranean context, the above-ground biomass can temporally disappear
because of fire or overgrazing and when concentrated flow erosion occurs, roots can play an important role in controlling
soil erosion rates. Unfortunately, information on root characteristics of Mediterranean plants, growing on semi-natural lands,
and their effects on the topsoil resistance to concentrated flow erosion is lacking. Therefore, typical Mediterranean grass,
herb, reed, shrub and tree root systems of plants growing in habitats that are prone to concentrated flow erosion (i.e. in
ephemeral channels, abandoned fields and steep badland slopes) are examined and their erosion-reducing potential was evaluated.
Root density (RD), root length density (RLD) and root diameters are measured for 26 typical Mediterranean plant species. RD
values and root diameter distribution within the upper 0.10–0.90 m of the soil profile are then transformed into relative
soil detachment rates using an empirical relationship in order to predict the erosion-reducing effect of root systems during
concentrated runoff. Comparing the erosion-reducing potential of different plant species allows ranking them according to
their effectiveness in preventing or reducing soil erosion rates by concentrated flow. RD in the 0.10 m thick topsoil ranges
between 0.13 kg m−3 for Bromus rubens (L.) and 19.77 kg m−3 for Lygeum spartum (L.), whereas RLD ranges between 0.01 km m−3 for Nerium oleander (L.) and 120.43 km m−3 for Avenula bromoides ((Gouan) H. Scholz.) Relative soil detachment rates, compared to bare soils, range between 0.3 × 10-12 and 0.7 for the 0.10 m thick topsoil. The results show that grasses such as Helictotrichon filifolium ((Lag.) Henrard), Piptatherum miliaceum ((L.) Coss.), Juncus acutus (L.), Avenula bromoides ((Gouan) H. Scholz), Lygeum spartum (L.) and Brachypodium retusum ((Pers.) Beauv.) have the highest potential to reduce soil erosion rates by concentrated flow in the 0–0.1 m topsoil. But
also shrubs such as Anthyllis cytisoides (L.) and Tamarix canariensis (Willd.), having high root densities in the topsoil, can reduce erosion rates drastically. Among the species growing in channels,
Juncus acutus (L.) has the highest erosion reducing potential, whereas Phragmites australis (Cav.) is the least effective. On abandoned fields, Avenula bromoides ((Gouan) H. Scholz) and Plantago albicans (L.) are the most effective species in reducing concentrated flow erosion rates, while Thymelaea hirsuta (L. (Endl.)) and Bromus rubens (L.) perform the worst. On steep badland slopes, Helictotrichon filifolium ((Lag.) Henrard) and Anthyllis cytisoides (L.) perform the best in the analysis of erosion reducing potential, while Ononis tridentata (L.) is the least effective species. These findings have implications for ecological restoration and management of erosion-prone
slopes. 相似文献
11.
Primary roots of maize (Zea mays L.) and pea (Pisum sativum L.) exhibit strong positive gravitropism. In both species, gravistimulation induces polar movement of calcium across the root tip from the upper side to the lower side. Roots of onion (Allium cepa L.) are not responsive to gravity and gravistimulation induces little or no polar movement of calcium across the root tip. Treatment of maize or pea roots with inhibitors of auxin transport (morphactin, naphthylphthalamic acid, 2,3,5-triiodobenzoic acid) prevents both gravitropism and gravity-induced polar movement of calcium across the root tip. The results indicate that calcium movement and auxin movement are closely linked in roots and that gravity-induced redistribution of calcium across the root cap may play an important role in the development of gravitropic curvature.Abbreviations 9-HFCA
9-hydroxyfluorenecarboxylic acid
- NPA
naphthylphthalamic acid
- TIBA
2,3,5-triiodobenzoic acid
- IAA
indole-3-acetic acid 相似文献
12.
N. S. Subbarao D. Yadav Anantha Padmanabha Nagaveni C. S. Singh S. K. Kavimandan 《Plant and Soil》1990,128(2):249-256
A field observation that roots of sandal wood tree (Santalum album (L.)) formed direct haustorial connections with root nodules of nodulating legumes was confirmed by pot culture studies on interaction between sandal wood plants and pigeonpea (Cajanus cajan (L.) Millsp.) or Pongamia glabra Vent. plants. The number of nodules and nitrogen content of plants decreased in parasitized nodulating species with corresponding increase in the nitrogen content of sandal plants. The root region of sandal had more of nitrogen-fixing bacteria and VAM fungi than those of pigeonpea. 相似文献
13.
A. L. BARTA 《Plant, cell & environment》1986,9(2):127-131
Abstract Differential rates of fermentation and energy production have been implicated in the response of plant species to extended root anoxia. This study describes the metabolic response to anaerobiosis of waterlogging-tolerant birdsfoot trefoil (Lotus corniculatus L.) and waterlogging-sensitive alfalfa (Medicago sativa L.). Studies were carried out on glasshouse-grown plants subjected to root anaerobiosis in nutrient solution. Rate of fermentation, as estimated by CO2 evolution, declined significantly upon anaerobiosis in both species but was proportionally less, relative to the aerobic control, in trefoil. Another indicator of carbon flux through glycolysis, the concentration of glucose-6-phosphate, was also significantly lower in trefoil roots relative to aerobic controls. Both species showed significantly increased root exudation of K+, sugars and andno-N, especially during the first 2 d of root anaerobiosis, indicating changes in membrane selective permeability. The energy status of roots subjected to anaerobiosis declined sharply in both species but trefoil roots maintained higher ATP/ADP ratios for up to 4 d of anaerobiosis. The results are consistent with the hypothesis that increased fermentation activity maintains a more favourable root energy status. This higher energy status may facilitate survival by maintaining crucial root activities, such as maintenance of membrane stability. 相似文献
14.
Hans Göransson Håkan Wallander Morten Ingerslev Ulrika Rosengren 《Plant and Soil》2006,286(1-2):87-97
The distribution of fine roots and external ectomycorrhizal mycelium of three species of trees was determined down to a soil depth of 55 cm to estimate the relative nutrient uptake capacity of the trees from different soil layers. In addition, a root bioassay was performed to estimate the nutrient uptake capacity of Rb+ and NH4+ by these fine roots under standardized conditions in the laboratory. The study was performed in monocultures of oak (Quercus robur L.), European beech (Fagus sylvatica L.) and Norway spruce [Picea abies (L.) Karst.] on sandy soil in a tree species trial in Denmark. The distribution of spruce roots was found to be more concentrated to the top layer (0–11 cm) than that of oak and beech roots, and the amount of external ectomycorrhizal mycelia was correlated to the distribution of the roots. The uptake rate of [86Rb+] by oak roots declined with soil depth, while that of beech or spruce roots was not influenced by soil depth. In modelling the nutrient sustainability of forest soils, the utilization of nutrient resources in deep soil layers has been found to be a key factor. The present study shows that the more shallow-rooted spruce can have a similar capacity to take up nutrients from deeper soil layers than the more deeply rooted oak. The distribution of roots and mycelia may therefore not be a reliable parameter for describing nutrient uptake capacity by tree roots at different soil depths. 相似文献
15.
Shoot and root physiological responses to localized zones of soil moisture in cultivated and wild lettuce (Lactuca spp.) 总被引:1,自引:0,他引:1
Cultivated crisphead lettuce (Lactuca sativa L.) has a shallower root system than its wild relative, Lactuca serriola L. The effects of localized soil water, at depth, on plant water relations, gas exchange and root distribution were examined in the two species using soil columns with the soil hydraulic-ally separated into two layers, at (0–20 cm and 20–81) cm, but permitting root growth between the layers. Three treatments were imposed on 7-week-old plants, and maintained for 4 weeks: (i) watering, both layers to field capacity; (ii) drying the upper layer while watering the lower layer to field capacity, and (iii) drying both layers. Drying only 0–20 cm of soil had no effect on leaf water status, net photosynthesis, stomatal conductance or biomass production in L. serriola compared to a well-watered control, but caused a short-term reduction (10 d) in leaf water status and photosynthesis in L. sativa that reduced final shoot production. The different responses may be explained by differences in root distribution. Just before the treatments commenced, L. serriola had 50% of total root length at 20–80 cm compared to 35% in L. sativa. Allocation of total biomass to roots in L. serriola was approximately double that in L. sativa. The wild species could provide germplasm for cultivated lettuces to extract more soil water from depth, which may improve irrigation efficiency. 相似文献
16.
Experiments were designed to provide information about the physiological basis of flood-tolerance in Senecio species. The oxygen concentration in roots of S. jacobaea L., S. viscosus L. and S. vulgaris L. became almost zero after transplantation to a solution of low oxygen concentration, and it was concluded that the flood-sensitivity of these Senecio species could be due to insufficient oxygen transport from the shoots to the roots. The oxygen concentration in the roots of the flood-tolerant S. congestus (R.Br.) DC., growing in a solution of low oxygen tension, was almost sufficient to maintain oxygen utilization at the rate observed in roots of plants, grown in an air-saturated solution. Oxygen utilization by roots of the flood-tolerant S. aquaticus Hill, growing in a solution of low oxygen tension, was inhibited 50%. However, the oxygen concentration in the roots of this species remained high enough to maintain cytochrome oxidase activity and oxidative phosphorylation at the rate observed in roots from an air-saturated environment. The activity of a second (“alternative”) oxidase must have been drastically reduced. Alternative NADH-oxidizing enzymes, like nitrate reductase which was induced by anaerobiosis in roots of S. aquaticus, might replace the regulatory function of the alternative oxidase. — Thus, in S. aquaticus root porosity and root length contributed to the maintenance of an oxygen concentration which was sufficient for uninhibited cytochrome oxidase activity and oxidative phosphorylation rate in roots growing in a solution of low oxygen tension. 相似文献
17.
Previous research suggested that the hydraulic properties of root systems
of intact plants could be described by two parameters: the hydraulic
conductivity (Lpr) or the slope of the
flow-density/water potential gradient relationship, and the offset or
minimum water potential gradient required to induce flow. In this study
Lpr and offset were correlated with anatomical
features of the root radial path in plants with contrasting root anatomy.
Two woody and three herbaceous species were examined which exhibit a range
of root anatomical features: Asparagus densiflorus
(Kunth) Jessop (asparagus), Dendrobium superbum Rchb.
f. (dendrobium), Glycine max (L.) Merr. (soybean),
Prunus persica (L.) Batsch. (peach), Citrus
aurantium L. (sour orange). Lpr varied
about 8-fold, and the offset varied about 6-fold among the five species.
Lpr was inversely related to root diameter
(r20.39) and cortex width
(r20.55), suggesting that species with thinner
roots or roots with a thin cortex had the highest Lpr.
Further observations suggested that the cortex width was a stronger
determinant of Lpr than root diameter. However, the
offset was not correlated with root diameter, stele diameter or cortex
width, but was >2-fold higher in species having an exodermis in the
root radial path (sour orange, asparagus, and dendrobium) compared to those
lacking an exodermis (peach and soybean). The data on root
Lr obtained were similar to those given in the
literature for both intact plants and excised roots which have been
measured with different techniques. It is concluded that
Lpr and offset, which describe the flow-water
potential relationship for intact root systems, are related to differences
in the root cortex; specifically, its thickness and the presence/absence of
a suberized exodermis. Hence, these anatomical differences may, in part,
cause the variability in root hydralic properties that exists among plant
species. 相似文献
18.
Tianshu Wu Jonah Wittkamper Hector E. Flores 《In vitro cellular & developmental biology. Plant》1999,35(3):259-264
Summary An in vitro coculture system has been established to study interactions between roots and aphids. Eight aphid species (Aphis spiraecola P., Trama rara M., Macrosiphum euphorbiae S., Rhopalosiphum padi L., Sitobion avenae F., Rhopalosiphum maidis F., Metopolophium dirhodum W., and Pemphigus populivenae F.) were reared on six species of hairy root cultures, Carthamus tinctorius L. cv N10, Tagetes patula L., Trichosanthes cucumerina L. var anguina, Hyoscyamus muticus L., Nicotiana tabacum L., and Beta vulgaris L. subsp. vulgaris. All species of aphids survived on root cultures for at least 2 d. Three cocultures have been maintained aseptically for
periods ranging from 2 mo. to over 2 yr. The coculture of R. padi on C. tinctorius cv N10 (N10-Rp) was used to study morphological and biochemical responses of roots under aphid herbivory. Aphid herbivory
caused browning of cultures, reduced root vegetative growth, and increased production of polyacetylenes in C. tinctorius cv N10 roots. Our results suggest that this coculture system may improve our understanding of interactions between aphids
and plant roots. 相似文献
19.
Mohammad Nuruzzaman Hans Lambers Michael D. A. Bolland Erik J. Veneklaas 《Plant and Soil》2006,281(1-2):109-120
This study investigates the distribution of carboxylates and acid phosphatases as well as the depletion of different phosphorus
(P) fractions in the rhizosphere of three legume crop species and a cereal, grown in a soil with two different levels of residual
P. White lupin (Lupinus albus L.), field pea (Pisum sativum L.), faba bean (Vicia faba L.) and spring wheat (Triticum aestivum L.) were grown in small sand-filled PVC tubes to create a dense root mat against a 38-μm mesh nylon cloth at the bottom,
where it was in contact with the soil of interest contained in another tube. The soil had either not been fertilised (P0)
or fertilised with 15 (P15) kg P ha−1 in previous years. The mesh size did not allow roots to grow into the soil, but penetration of root hairs and diffusion of
nutrients and root exudates was possible, and a rhizosphere was established. At harvest, thin (1 mm) slices of this rhizosphere
soil were cut, down to a 10-mm distance from the mesh surface. The rhizosphere of white lupin, particularly in the P0 treatment,
contained citrate, mostly in the first 3 mm, with concentrations decreasing with distance from the root. Acid phosphatase
activity was enhanced in the rhizosphere of all species, as compared with bulk soil, up to a distance of 4 mm. Phosphatase
activity was highest in the rhizosphere of white lupin, followed by faba bean, field pea and wheat. Both citrate concentrations
and phosphatase activities were higher in P0 compared with P15. The depletion of both inorganic (Pi) and organic (Po) phosphorus fractions was greatest at the root surface, and decreased gradually with distance from the root. The soil P fractions
that were most depleted as a result of root activity were the bicarbonate-extractable (0.5 M) and sodium hydroxide-extractable (0.1 M) pools, irrespective of plant species. This study suggests that differences among the studied species in use of different
P pools and in the width of the rhizosphere are relatively small. 相似文献
20.
Is Fe deficiency rather than P deficiency the cause of cluster root formation in Casuarina species? 总被引:1,自引:0,他引:1
Zaïd El Houssine Arahou Moustapha Diem Hoang G. El Morabet Rachida 《Plant and Soil》2003,248(1-2):229-235
When subjected, directly (through nutritional deficiencies) or indirectly (through alkaline constraints leading to such deficiencies) to nutrient deficiencies, certain plants respond by developing special root structures called cluster roots. This phenomenon can be considered as an ecophysiological response to a specific nutrient deficiency enabling plants to enhance nutrient uptake. Experiments conducted on an alkaline and an acid soil showed that Casuarina glauca (Sieber ex Spreng.) produced cluster roots only in the alkaline soil and not in the acid soil. In addition, iron (Fe) and phosphorus (P) deficiencies were examined separately or together to determine their effect on cluster root formation in C. glauca seedlings grown hydroponically. Results from experiments carried out on three Casuarina species (C. glauca, C. cunninghamiana Miq. and C. equisetifolia L.) indicated that Fe is involved in cluster root formation. In nutrient media lacking P but containing Fe, no cluster roots formed while seedlings receiving P and lacking Fe developed cluster roots. When incubated on chrome-azurol S-agar on blue plates (CAS assay), a technique used routinely to detect the production of siderophores by micro-organisms, the root system of Fe-deficient plants exhibited orange halos around cluster roots, indicating production of a ferric-chelating agent. It is concluded that the capacity of cluster roots of C. glauca to chelate Fe allows the plant to grow normally on alkaline soils. 相似文献