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1.
Changes in root size and distribution in relation to nitrogen accumulation during maize breeding in China 总被引:3,自引:0,他引:3
Xiaochao Chen Jie Zhang Yanling Chen Qian Li Fanjun Chen Lixing Yuan Guohua Mi 《Plant and Soil》2014,374(1-2):121-130
Background and aims
Modern maize breeding has increased maize yields worldwide. The changes in above-ground traits accompanying yield improvement are well-known, but less information is available as to the effect of modern plant breeding on changes in maize root traits.Methods
Root growth, nitrogen uptake, dry matter accumulation and yield formation of six maize hybrids released from 1973 to 2000 in China were compared. Experiments were conducted under low and high nitrogen supply in a black soil in Northeast China in 2010 and 2011.Results
While nitrogen accumulation, dry matter production and yield formation have been increased, modern maize breeding in China since 1990 has reduced root length density in the topsoil without much effect on root growth in the deeper soil. The efficiency of roots in acquiring N has increased so as to match the requirement of N accumulation for plant growth and yield formation. The responses of root growth, nitrogen and dry matter accumulation, and grain yield to low-N stress were similar in the more modern hybrids as in the older ones.Conclusions
Modern maize breeding has constitutively changed root and shoot growth and plant productivity without producing any specific enhancement in root responsiveness to soil N availability. 相似文献2.
Vincent Walker Olivier Couillerot Andreas Von Felten Floriant Bellvert Jan Jansa Monika Maurhofer René Bally Yvan Mo?nne-Loccoz Gilles Comte 《Plant and Soil》2012,356(1-2):151-163
Background and aims
Many plant-beneficial microorganisms can influence secondary plant metabolism, but whether these effects add up when plants are co-inoculated is unclear. This issue was assessed, under field conditions, by comparing the early impacts of seed inoculation on secondary metabolite profiles of maize at current or reduced mineral fertilization levels.Methods
Maize seeds were inoculated singly with selected strains from bacterial genera Pseudomonas and Azospirillum or mycorrhizal genus Glomus, or with these strains combined two by two or all three together. At 16?days, maize root methanolic extracts were analyzed by RP-HPLC and secondary metabolites (phenolics, flavonoids, xanthones, benzoxazionoids, etc.) identified by LC/MS.Results
Inoculation did not impact on plant biomass but resulted in enhanced total root surface, total root volume and/or root number in certain inoculated treatments, at reduced fertilization. Inoculation led to qualitative and quantitative modifications of root secondary metabolites, particularly benzoxazinoids and diethylphthalate. These modifications depended on fertilization level and microorganism(s) inoculated. The three selected strains gave distinct results when used alone, but unexpectedly all microbial consortia gave somewhat similar results.Conclusions
The early effects on maize secondary metabolism were not additive, as combining strains gave effects similar to those of Glomus alone. This is the first study demonstrating and analyzing inoculation effects on crop secondary metabolites in the field. 相似文献3.
4.
Background and aims
Roots have morphological plasticity to adapt to heterogeneous nutrient distribution in soil, but little is known about crop differences in root plasticity. The objective of this study was to evaluate root morphological strategies of four crop species in response to soil zones enriched with different nutrients.Methods
Four crop species that are common in intercropping systems [maize (Zea mays L.), wheat (Triticum aestivum L.), faba bean (Vicia faba L.), and chickpea (Cicer arietinum L.)] and have contrasting root morphological traits were grown for 45 days under uniform or localized nitrogen and phosphorus supply.Results
For each species tested, the nutrient supply patterns had no effect on shoot biomass and specific root length. However, localized supply of ammonium plus phosphorus induced maize and wheat root proliferation in the nutrient-rich zone. Localized supply of ammonium alone suppressed the whole root growth of chickpea and maize, whereas localized phosphorus plus ammonium reversed (maize and chickpea ) the negative effect of ammonium. The localized root proliferation of chickpea in a nutrient-rich zone did not increase the whole root length and root surface area. Faba bean had no significant response to localized nutrient supply.Conclusions
The root morphological plasticity is influenced by nutrient-specific and species-specific responses, with the greater plasticity in graminaceous (eg. maize) than leguminous species (eg. faba bean and chickpea). 相似文献5.
Chantal Planchamp Dirk Balmer Andreas Hund Brigitte Mauch-Mani 《Plant and Soil》2013,367(1-2):605-614
Background and aims
The root surface of a plant usually exceeds the leaf area and is constantly exposed to a variety of soil-borne microorganisms. Root pathogens and pests, as well as belowground interactions with beneficial microbes, can significantly influence a plants' performance. Unfortunately, the analysis of these interactions is often limited because of the arduous task of accessing roots growing in soil. Here, we present a soil-free root observation system (SF-ROBS) designed to grow maize (Zea mays) plants and to study root interactions with either beneficial or pathogenic microbes.Methods
The SF-ROBS consists of pouches lined with wet filter paper supplying nutrient solution.Results
The aspect of maize grown in the SF-ROBS was similar to soil-grown maize; the plant growth was similar for the shoot but different for the roots (biomass and length increased in the SF-ROBS). SF-ROBS-grown roots were successfully inoculated with the hemi-biotrophic maize fungal pathogen Colletotrichum graminicola and the beneficial rhizobacteria Pseudomonas putida KT2440. Thus, the SF-ROBS is a system suitable to study two major belowground phenomena, namely root fungal defense reactions and interactions of roots with beneficial soil-borne bacteria.Conclusions
This system contributes to a better understanding of belowground plant microbe interactions in maize and most likely also in other crops. 相似文献6.
Physiological and genetic characterization of rice nitrogen fixer PGPR isolated from rhizosphere soils of different crops 总被引:1,自引:0,他引:1
Safiullah Habibi Salem Djedidi Kunlayakorn Prongjunthuek Md Firoz Mortuza Naoko Ohkama-Ohtsu Hitoshi Sekimoto Tadashi Yokoyoma 《Plant and Soil》2014,379(1-2):51-66
Aims
We aimed to identify plant growth-promoting rhizobacteria that could be used to develop a biofertilizer for rice.Methods
To obtain plant growth-promoting rhizobacteria, rhizosphere soils from different crops (rice, wheat, oats, crabgrass, maize, ryegrass, and sweet potato) were inoculated to rice plants. In total, 166 different bacteria were isolated and their plant growth-promoting traits were evaluated in terms of colony morphology, indole-3-acetic acid production, acetylene reduction activity, and phosphate solubilization activity. Moreover, genetic analysis was carried out to evaluate their phylogenetic relationships based on 16S rRNA sequence data.Results
Strains of Bacillus altitudinis, Pseudomonas monteilii, and Pseudomonas mandelii formed associations with rice plants and fixed nitrogen. A strain of Rhizobium daejeonense showed nitrogen fixation activity in an in vitro assay and in vivo. Strains of B. altitudinis and R. daejeonense derived from rice rhizosphere soil, strains of P. monteilii and Enterobacter cloacae derived from wheat rhizosphere soil, and a strain of Bacillus pumilus derived from maize rhizosphere soil significantly promoted rice plant growth.Conclusions
These methods are effective to identify candidate species that could be developed as biofertilizers for target crops. 相似文献7.
Aims
Many studies have proved that EDTA (ethylenediaminetetraacetic acid), EDDS ([S, S’]-ethylenediamine disuccinic acid), and other chelating agents significantly enhance phyto-extraction of copper (Cu) from soil. However, some key factors, such as changes in membrane permeability of root cells and subcellular distribution of Cu and Cu-EDDS complex in leaves and roots, remain unresolved.Methods
A pot-culture experiment was conducted using soil artificially contaminated with Cu to different degrees to compare its effect on the above factors and the relationship between them in maize (Zea mays L.).Results
Treatment with 0.5–6.0?mmol?kg?1 (soil) EDDS increased membrane permeability in root cells significantly (p?<?0.05). Chelated Cu accounted for 14.6%–17.4% of the total Cu content of roots and 77.7%–78.8% of that of leaves and was distributed mainly in cell walls in both.Conclusions
EDDS increases Cu accumulation in shoots mainly by increasing the content of soluble Cu in soil and membrane permeability of root cells. Cu in soil may be absorbed through the apoplastic pathway into the root xylem, translocated to the shoots, and accumulated there as a Cu-EDDS complex. 相似文献8.
Aim
Root biomass has long been under-represented in biodiversity–ecosystem functioning studies, despite its dominance in biomass in many arid and semi-arid ecosystems. We aimed to explore the multivariate control over root biomass by plant diversity, together with other biotic and abiotic factors and to evaluate the relative importance of these factors.Methods
Above- and below-ground traits of 13 communities and soil properties were measured in semi-arid grasslands on the Loess Plateau, China. Structural equation modeling (SEM) was used to evaluate the relative importance of the community and soil characteristics, emphasizing the direct and indirect effects of plant diversity on root biomass.Results
Significant indirect effects of plant species richness on root biomass were found, although no direct correlation was detected between them. In the indirect pathways, plant species richness showed a positive effect on soil total nitrogen, but a significant negative influence on soil total carbon. Soil total nitrogen and plant diversity had the largest and smallest total effect respectively on root biomass in the model.Conclusions
Plant species richness was not the strongest determinant of root biomass but had a significant indirect effect, mediated through soil total carbon and nitrogen. This study suggests that greater plant species richness, through a positive influence on soil total nitrogen, may indirectly promote root carbon stock. 相似文献9.
Root-induced changes in radial oxygen loss, rhizosphere oxygen profile, and nitrification of two rice cultivars in Chinese red soil regions 总被引:4,自引:0,他引:4
Aims
To evaluate the external and internal morphological differences of roots that might influence rice root radial oxygen loss (ROL) and the corresponding rhizosphere nitrification activity, growth characteristics and nitrogen nutrition of rice.Methods
The root ROL and rhizosphere oxygen profile were determined using a miniaturised Clark-type oxygen microelectrode system, and the rhizosphere nitrification activity was studied with a short-term nitrification activity assay.Results
The rice biomass, nitrogen accumulation and nitrogen use efficiency (NUE) of ZH (high yield) were significantly higher than those of HS (low yield). The root biomass, number, diameter and porosity of ZH were also much greater than those of HS. The inner and surface oxygen concentrations of the root of ZH were significantly higher than those of HS. The order of paddy soil oxygen penetration depth was ZH?>?HS?>?CK, and the order of the oxygen concentrations detected in the water layer and rhizosphere soil was the same. The rhizosphere nitrification activity and nitrate concentration of ZH were significantly higher than those of HS.Conclusions
More porous and thicker roots improved the individual root ROL, and more adventitious root numbers enhanced the entire plant ROL and correspondingly improved the rhizosphere nitrification activity, which might influence the growth and nitrogen nutrition of rice. 相似文献10.
Liebig’s law of the minimum applied to a greenhouse gas: alleviation of P-limitation reduces soil N2O emission 总被引:2,自引:0,他引:2
Background and aims
Emission of the greenhouse gas (GHG) nitrous oxide (N2O) are strongly affected by nitrogen (N) fertilizer application rates. However, the role of other nutrients through stoichiometric relations with N has hardly been studied. We tested whether phosphorus (P) availability affects N2O emission. We hypothesized that alleviation of plant P-limitation reduces N2O emission through lowering soil mineral N concentrations.Methods
We tested our hypothesis in a pot experiment with maize (Zea mays L.) growing on a P-limiting soil/sand mixture. Treatment factors included P and N fertilization and inoculation with Arbuscular Mycorrhizal Fungi (AMF; which can increase P uptake).Results
Both N and P fertilization, as well as their interaction significantly (P?<?0.01) affected N2O emission. Highest N2O emissions (2.38 kg N2O-N ha?1) were measured at highest N application rates without P fertilization or AMF. At the highest N application rate, N2O fluxes were lowest (0.71 kg N2O-N ha?1) with both P fertilization and AMF. The N2O emission factors decreased with 50 % when P fertilization was applied.Conclusions
Our results illustrate the importance of the judicious use of all nutrients to minimize N2O emission, and thereby further underline the intimate link between sound agronomic practice and prudent soil GHG management. 相似文献11.
Jeffrey M. Warren Hassina Bilheux Misun Kang Sophie Voisin Chu-Lin Cheng Juske Horita Edmund Perfect 《Plant and Soil》2013,366(1-2):683-693
Background and aims
Knowledge of plant water fluxes is critical for assessing mechanistic processes linked to biogeochemical cycles, yet resolving root water transport dynamics has been a particularly daunting task. Our objectives were to demonstrate the ability to non-invasively monitor individual root functionality and water fluxes within Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings using neutron imaging.Methods
Seedlings were propagated for 1–3 weeks in aluminum chambers containing sand. Pulses of water or deuterium oxide were then tracked through the root systems by collecting consecutive radiographs during exposure to a cold-neutron source. Water flux was manipulated by cycling on a growth lamp to alter foliar demand for water.Results
Neutron radiography readily illuminated root structure, root growth, and relative plant and soil water content. After irrigation there was rapid root water uptake from the newly wetted soil, followed by hydraulic redistribution of water through the root system to roots terminating in dry soil. Water flux within individual roots responded differentially to foliar illumination based on supply and demand of water within the root system.Conclusions
Sub-millimeter scale image resolution revealed timing and magnitudes of root water uptake, redistribution within the roots, and root-shoot hydraulic linkages—relationships not well characterized by other techniques. 相似文献12.
Zinc fertilizer placement affects zinc content in maize plant 总被引:1,自引:0,他引:1
Yue-Qiang Zhang Li-Li Pang Peng Yan Dun-Yi Liu Wei Zhang Russell Yost Fu-Suo Zhang Chun-Qin Zou 《Plant and Soil》2013,372(1-2):81-92
Background and aims
Adequate zinc (Zn) in maize (Zea mays L.) is required for obtaining Zn-enriched grain and optimum yield. This study investigated the impact of varying Zn fertilizer placements on Zn accumulation in maize plant.Methods
Two pot experiments with same design were conducted to investigate the effect of soil Zn heterogeneity by mixing ZnSO4·7H2O (10 mg Zn kg?1 soil on an average) in 10–15, 0–15, 25–30, 0–30, 30–60 and 0–60 cm soil layers on maize root growth and shoot Zn content at flowering stage in experiment-1, and assessing effects on grain Zn accumulation at mature stage in experiment-2.Results
In experiment-1, Zn placements created a large variation in soil DTPA-Zn concentration (0.3–29.0 mg kg?1), which induced a systemic and positive response of root growth within soil layers of 0–30 cm; and shoot Zn content was increased by 102 %–305 % depending on Zn placements. Supply capacity of Zn in soil, defined as sum of product of soil DTPA-Zn concentration and root surface area at different soil layers, was most related to shoot Zn content (r?=?0.82, P?<?0.001) via direct and indirect effects according to path analysis. In experiment-2, Zn placements increased grain Zn concentration by up to 51 %, but significantly reduced the grain Zn harvest index from 50 % by control to about 30 % in average.Conclusion
Matching the distribution of soil applied Zn with root by Zn placement was helpful to maximize shoot Zn content and grain Zn concentration in maize. 相似文献13.
A combination of humic substances and Herbaspirillum seropedicae inoculation enhances the growth of maize (Zea mays L.) 总被引:1,自引:0,他引:1
Luciano Pasqualoto Canellas Dariellys Martínez Balmori Leonardo Oliveira Médici Natália Oliveira Aguiar Eliemar Campostrini Raul C. C. Rosa Arnoldo R. Façanha Fábio Lopes Olivares 《Plant and Soil》2013,366(1-2):119-132
Background
Endophytic diazotrophic bacteria colonize several non-leguminous plants and promote plant growth. Different mechanisms are involved in bacteria-induced plant growth promotion, including biological nitrogen fixation (BNF), mineral solubilization, production of phytohormones, and pathogen biocontrol. Herbaspirillum seropedicae is a broad-host-range endophyte that colonizes sugarcane, rice, wheat, sorghum, and maize, and has been used as a biofertilizer. Contrasting results between greenhouse and field experiments have prompted efforts to improve the consistency of the plant response to microbial stimulation.Aims
The aim of this study was to evaluate the effect of the presence of humic substances on inoculation of maize (Zea mays L.) with H. seropedicae.Methods
Two experiments were conducted: one in the greenhouse using sand and nutrient solution and the other a field trial in soil with low natural fertility and to which was applied N in the form of urea (50 kg ha?1). In the greenhouse, pre-emerging seeds were inoculated with a solution of H. seropedicae (109 cells mL?1) in the presence of humic substances isolated from vermicompost (10, 20, or 30 mg C?L?1); in the field trial, bacteria combined with humate were added as a foliar spray (450 L?ha?1).Results
At early stages (7 and 45 days old) in the greenhouse, the treatment activated plant metabolism including enhancement of plasma membrane H+-ATPase activity, alteration of sugar and N metabolism, and greater net photosynthesis. The number of viable bacterial cells was higher in root tissues when inoculation was in the presence of soluble humic substances. Foliar application of endophytic diazotrophic bacteria and humic substances increased maize grain production 65 % under field conditions. These results show a promising use of humic substances to improve the benefit of endophytic diazotrophic inoculation. 相似文献14.
Aims
The purpose of this study was to test the hypotheses that soil nutrient patchiness can differentially benefit the decomposition of root and shoot litters and that this facilitation depends on plant genotypes.Methods
We grew 15 cultivars (i.e. genotypes) of winter wheat (Triticum aestivum L.) under uniform and patchy soil nutrients, and contrasted their biomass and the subsequent mass, carbon (C) and nitrogen (N) dynamics of their root and shoot litters.Results
Under equal amounts of nutrients, patchy distribution increased root biomass and had no effects on shoot biomass and C:N ratios of roots and shoots. Roots and shoots decomposed more rapidly in patchy nutrients than in uniform nutrients, and reductions in root and shoot C:N ratios with decomposition were greater in patchy nutrients than uniform nutrients. Soil nutrient patchiness facilitated shoot decomposition more than root decomposition. The changes in C:N ratios with decomposition were correlated with initial C:N ratios of litter, regardless of roots or shoots. Litter potential yield, quality and decomposition were also affected by T. aestivum cultivars and their interactions with nutrient patchiness.Conclusions
Soil nutrient patchiness can enhance C and N cycling and this effect depends strongly on genotypes of T. aestivum. Soil nutrient heterogeneity in plant communities also can enhance diversity in litter decomposition and associated biochemical and biological dynamics in the soil. 相似文献15.
Background and aims
Lately sweet sorghum (S) has attracted great interest as an alternative feedstock for biofuel production due to its high yielding potential and better adaptation to drought than maize (M). However, little is known about the response of newly developed sweet sorghum genotypes to water deficits, especially at the root level and its water uptake patterns. The objective of this study was to compare the water uptake capacity, growth and developmental characteristics at the root and canopy levels of a sweet sorghum hybrid (Sorghum bicolor cv. Sucro 506) with those of maize (Zea mays cv. PR32F73) at two water regimes.Methods
The trial was setup in a total of 20 rhizotrons (1?m3), where calibrated soil moisture probes were installed for monitoring and adjusting the soil moisture content to 25% (well-watered, W) and 12% (drought stress, D).Results
DS was able to sustain its physiological activity close to that of WS plants, while maize was not. The biomass production potential of DS was reduced about 38%, while in maize the reduction was 47%. The water use efficiency (WUE), however, was increased by 20% in sweet sorghum and reduced in 5% in maize. Moreover, in contrast to maize the root length density and water uptake capacity of DS was enhanced. Root water uptake efficiency in DM was sustained close to its potential, but not in sweet sorghum.Conclusions
In summary, the better adaptation to drought of sweet sorghum is explained by increased WUE, sustained physiological activity and enlarged root system. It is also associated with a reduced water uptake efficiency compared to its control but maintained compared to maize. 相似文献16.
Sonja Schmidt Peter J. Gregory Dmitri V. Grinev A. Glyn Bengough 《Plant and Soil》2013,372(1-2):609-618
Background
We investigated interacting effects of matric potential and soil strength on root elongation of maize and lupin, and relations between root elongation rates and the length of bare (hairless) root apex.Methods
Root elongation rates and the length of bare root apex were determined for maize and lupin seedlings in sandy loam soil of various matric potentials (?0.01 to ?1.6 MPa) and bulk densities (0.9 to 1.5 Mg m?3).Results
Root elongation rates slowed with both decreasing matric potential and increasing penetrometer resistance. Root elongation of maize slowed to 10 % of the unimpeded rate when penetrometer resistance increased to 2 MPa, whereas lupin elongated at about 40 % of the unimpeded rate. Maize root elongation rate was more sensitive to changes in matric potential in loosely packed soil (penetrometer resistances <1 MPa) than lupin. Despite these differing responses, root elongation rate of both species was linearly correlated with length of the bare root apex (r2 0.69 to 0.97).Conclusion
Maize root elongation was more sensitive to changes in matric potential and mechanical impedance than lupin. Robust linear relationships between elongation rate and length of bare apex suggest good potential for estimating root elongation rates for excavated roots. 相似文献17.
Background and Aims
We developed a method for processing roots from soil cores and monoliths in the laboratory to reduce the time and cost devoted to separating roots from debris and improve the accuracy of root variable estimates. The method was tested on soil cores from a California oak savanna, with roots from trees, Quercus douglasii, and annual grasses.Methods
In the randomized sampling method, one isolates the sample fraction consisting of roots and organic debris?<?= 1 cm in length, and randomizes it through immersion in water and vigorous mixing. Sub-samples from the mixture are then used to estimate the percentage of roots in this fraction, thereby enabling an estimate of total sample biomass.Results
We found that root biomass estimates, determined through the randomization method, differed from total root biomass established by meticulously picking every root from a sample with an error of 3.0 % +/? 0.6 %?s.e.Conclusions
This method greatly reduces the time and resources required for root processing from soil cores and monoliths, and improves the accuracy of root variable estimates compared to standard methods. This gives researchers the ability to increase sample frequency and reduce the error associated with studying roots at the landscape and plant scales. 相似文献18.
Stéphanie Mahieu José Escarré Brigitte Brunel Angélique Méjamolle Souhir Soussou Antoine Galiana Jean-Claude Cleyet-Marel 《Plant and Soil》2014,375(1-2):175-188
Background and aims
The association of the legume Anthyllis vulneraria and the grass Festuca arvernensis, was found to be very efficient for the phytostabilisation of highly multi-metal contaminated mine tailings. Our objective was to quantify the contribution of Anthyllis inoculated with its symbiotic bacteria Mesorhizobium metallidurans to the soil N pool and to test whether a starter nitrogen fertilization may improve symbiotic nitrogen fixation and the growth of Festuca.Methods
Plants of Festuca and of Anthyllis inoculated with M. metallidurans were grown separately during eight months in pots filled with mine contaminated soil. Estimation of the N fluxes was realized using 15?N isotopic methods.Results
Starter N fertilization (28 kg N ha?1) improved symbiotic N2 fixation and the growth of both species. Belowground N balance (N rhizodeposition – soil N uptake) of the non-fertilized Anthyllis at maturity was negative (?30.6 kg N ha?1). However, the amount of N derived from fixation, including above- and belowground parts, was 78.6 kg N ha?1, demonstrating the ability of this symbiotic association to improve soil N content after senescence.Conclusions
i) soil N enrichment by the N2-fixing symbiotic association occurs after plant senescence, when decaying leaves and shoots are incorporated into the soil; ii) application of a starter fertilization is an efficient solution to improve phytostabilisation of highly contaminated sites. 相似文献19.
Aims
We determined whether nitrogen (N) deposition on phosphorus (P)-limited soil could increase Schima superba growth or alter root formation or P efficiency. The effects of N deposition on S. superba were also used to investigate the N/P requirements of plants of different provenances.Methods
One-year-old S. superba seedlings from eight geographic areas were grown in P-limited soil and treated with N (0, 50, 100, and 200 -kg?N?ha?1?year?1; i.e., control, N50, N100, or N200, respectively). Seedling growth, root development, phosphorus acquisition efficiency (PAE), and phosphorus utilization efficiency (PUE) were measured.Results
S. superba responded positively to N supplementation. Seedling growth and dry biomass were highest with N100 treatment and lowest with N200. Root biomass and acquisition of soil P were greatest with N100. Significant differences were observed among plants of different geographical provenances. PAE and PUE had a strong relationship with root growth in plants subjected to N100 treatment.Conclusion
A threshold for N and P requirements related to different genetic conditions and soil nutrients may exist for S. superba. Root growth and PAE can be divided into three categories based on soil nitrate levels. Nutrients were found to control root morphology and to enhance aboveground differences. 相似文献20.