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1.
丛枝菌根真菌可以与绝大多数陆生植物共生,它可以吸收铵态氮、硝态氮、一些氨基酸和一些复杂的有机氮素,吸收的氮素在根外菌丝中转化成精氨酸,并以这种形式运输到根内菌丝,在根内菌丝和根细胞界面,精氨酸再进一步转化为NH4^＋后转移到宿主植物体,参与植物氮素代谢,而转移的氮量及对宿主植物氮营养的贡献与宿主植物、真菌以及基质养分和水分条件有关．  相似文献   

2.
The roots of most land plants establish intimate associations with soil fungi. This association of plant roots with fungi is termed mycorrhiza. It is a marriage between two highly dissimilar organisms based on mutual exchange of nutrients: while the plants provide photosynthetically made carbon compounds to the fungi, the fungi in turn provide to the plants nitrogen and phosphorus scavenged from the breakdown of organic polymers in natural substrates. This mutually beneficial partnership makes possible the green cover on Earth and of all life, ultimately, dependent on plants.  相似文献   

3.
The effect of Al and Cd on the growth, photosynthesis, and accumulation of Al, Cd and plant nutrients in two soybean genotypes were determined using hydroponic culture. There were six treatments: pH 6.5; pH 4.0; pH 6.5 1.0 μmol/L Cd; pH 4.0 1.0 μmol/L Cd; pH 4.0 150 μmol/L Al; pH 4.0 1.0 μmol/L Cd 150 μmol/L Al. The low pH (4.0) and Al treatments caused marked reduction in root length, shoot height, dry weight, chlorophyll content (SPAD value) and photosynthetic rate. Al-sensitive cv. Zhechun 2 accumulated comparatively more Al and Cd in plants than Al-tolerant cv. Liao 1. Compared with pH 6.5, pH 4.0 resulted in significant increase in Cd and Al concentration in plants. Combined application of Cd and Al enhanced their accu-mulation in roots, but caused a reduction in shoots. The concentrations of all 10 nutrients (P, K, Ca, Mg, Fe, Mn, Cu, Zn and B), except Mo were also increased when plants were exposed to pH lower than pH 6.5. Al addition caused a reduction in the con-centration of most nutrients in plant roots and shoots; but K, Mn and Zn in roots were increased. Treatments with Cd alone or together with Al reduced the concentrations of all the plant nutrients in plants. Al-sensitive genotype Zhechun 2 has lower nutrient concentration than Al-tolerant genotype Liao 1. The current findings imply that Al and Cd are synergistic in their effect on plant growth, physiological traits and nutrient uptake.  相似文献   

4.
水体富营养化是指水体内氮磷营养元素富集,使水质恶化,藻类异常增殖的过程.生态浮床技术,通过植物根系吸收、吸附、截留及根系微生物分解水体中的氮、磷等营养物质,再通过收割植物将其搬离水体,从而达到净化水质的目的.国内外研究较多的水生植物有挺水植物、漂浮植物、浮叶植物和沉水植物等.为了克服传统生态浮床净污主体的单一性,在其基础上衍出了水生动植物组合式生态浮床.  相似文献   

5.
多不饱和脂肪酸(PUFAs)的生物合成与功能   总被引：2，自引：0，他引：2  
多不饱和脂肪酸（PUFAs）为一种独特的生物活性物质，在生物系统中具有广泛的功能，是一种关键的营养物质。随着PUFAS开发应用领域的扩大，纯PUFAs脂质的需求量越来越多，而来自于植物、哺乳动物和海洋鱼的PUFAs远远不能满足市场需求，微生物特别是藻类、真菌能合成几乎所有的PUFAs，并能在工业规模上培育有开发价值的可替代的生物资源。  相似文献   

6.
Interaction of salinity （NaCI） and cadmium （Cd） on growth, mineral nutrients, Na and Cd accumulation in four barley genotypes differing in salt tolerance was studied in a hydroponic experiment. Cd, NaCI and their combined stresses reduced Ca and Mg concentrations in roots and shoots, K concentration in shoots, increased K and Cu concentrations in roots relative to control, but had non-significant effect on micronutrients Cu, Fe and Mn concentrations in shoot. The three stresses reduced accumulation of most tested nutrients in both roots and shoots, except NaCI and NaCl＋Cd stresses for root K and shoot Cu accumulation in salt tolerant genotypes. The salt tolerant genotypes did not have higher nutrient concentration and accumulation than the sensitive ones when exposed to Cd and NaCI stresses. In conclusion, the affecting mechanism of Cd stress on nutrients was to some extent different from salinity stress, and the NaCl＋Cd stress was not equal to additional Cd and NaCI stresses, probably due to the different valence and competitive site of Na^＋ and Cd^2＋. NaCI addition in the Cd-containing medium caused remarkable reductions in both Cd concentration and accumulation, with the extent of reduction being also dependent on genotypes. The salt-tolerant genotypes had lower Na concentration than sensitive ones.  相似文献   

7.
Mycorrhizoremediation an enhanced form of phytoremediation   总被引：2，自引：0，他引：2  
Study of plant roots and the diversity of soil micro biota, such as bacteria, fungi and microfauna associated with them, is important for understanding the ecological complexities between diverse plants, microbes, soil and climates and their role in phytoremediation of contaminated soils. The arbuscular mycorrhizal fungi （AMF） are universal and ubiquitous rhizosphere mi- croflora forming symbiosis with plant roots and acting as biofertilizers, bioprotactants, and biodegraders. In addition to AMF, soils also contain various antagonistic and beneficial bacteria such as root pathogens, plant growth promoting rhizobacteria including free-living and symbiotic N-fixers, and mycorrhiza helping bacteria. Their potential role in phytoremediation of heavy metal （HM） contaminated soils and water is becoming evident although there is need to completely understand the ecological complexities of the plant-microbe-soil interactions and their better exploitation as consortia in remediation strategies employed for contaminated soils. These multitrophic root microbial associations deserve multi-disciplinary investigations using molecular, biochemical, and physiological techniques. Ecosystem restoration of heavy metal contaminated soils practices need to incorporate microbial biotechnology research and development. This review highlights the ecological complexity and diversity of plant-microbe-soil combinations, particularly AM and provides an overview on the recent developments in this area. It also discusses the role AMF play in phytorestoration of HM contaminated soils, i.e. mycorrhizoremediation.  相似文献   

8.
Santalum album Linn. is an evergreen and hemi-parasitic tree, the heartwood-sandalwood of which was used during a long history in traditional Chinese medicine. Kuhnia rosmarinifolia Vent. is a good host for 1- or 2-year-old growing S. album. The interaction between S. album and K. rosmarinifolia is still little known. Many studies have been carried out on a number of plants for identification and diversity of endophytes. In this study, in total 25 taxa of endophytic fungi were isolated from the roots of S. album and the roots of K. rosmarinifolia. The most frequently isolated genera were Penicillium sp. 1 and Fusarium sp. 1 in the roots of S. album and K. rosmarinifolia, respectively. S. album is a root parasite of K. rosmarinifolia. The interesting result is that they apparently do not share the same endophytic fungi isolates. This study for the first time explored the content of endophytic fungi from S. album and K. rosmarinifolia, which provides important information for further studies.  相似文献   

9.
Seed treatment with endophytic fungi has been regarded as an effective method for plant parasitic nematode control. Endophytic fungi from cucumber seedlings were isolated and screened for their potential to be used as seed treatment agents against Meloidogyne incognita. Among the 294 isolates screened, 23 significantly reduced galls formed by M. incognita in greenhouse test. The 10 most effective isolates were Fusarium (5), Trichoderma (1), Chaetomium (1), Acremonium (1), Paecilomyces (1), and Phyllosticta (1). Their control efficacies were repeatedly tested and their colonizations as well as in vitro activity against M. incognita were studied. They reduced the number of galls by 24.0%–58.4% in the first screening and 15.6%–44.3% in the repeated test, respectively. Phyllosticta Ph511 and Chaetomium Ch1001 had high colonizations on both the roots and the aboveground parts of cucumber seedlings. Fusarium isolates had colonization preference on the roots, their root colonizations ranging from 20.1% to 47.3% of the total root area. Trichoderma Tr882, Paecilomyces Pa972, and Acremonium Ac985 had low colonizations on both the roots and the aboveground parts. Acremonium Ac985, Chaetomium Ch1001, Paecilomyces Pa972, and Phyllosticta Ph511 produced compounds affecting motility of the second stage juveniles of M. incognita. Based on these results, Chaetomium Ch1001 was considered to have the highest potential as a seed treatment agent for M. incognita biocontrol.  相似文献   

10.
The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus ofGlomus intraradices and/or infection with pathogenic strain ofPhytophthora capsici, and the biological control effect ofG. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated withG. intraradices (Gi), (2) plants pre-inoculated withG. intraradices and then infected withP. capsici (Gi+Pc). (3) plants infected withP. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal colonization rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection ofP. capsici was completely eliminated by pre-inoculation with antagonisticG. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45000, 53000 and 114000) were present in Pc-treated roots, while two major bands (53000 and 114000) and one minor band (45000) were present in spectra of Gi+Pc-treated roots, the 45000 POD isozyme was significantly suppressed byG. intraradices, suggesting that the 45000 POD isozyme was induced by the pathogen infection but not induced by the antagonisticG. intraradices. A 60000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonisticG. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected byP. capsici. The results suggested thatG. intraradices is a potentially effective protection agent againstP. capsici. Project supported by Korea Science and Engineering Foundation (KOSEF) through the Agricultural Plants Stress Research Center (APSRC) at Chonnam National University, Korea  相似文献   

11.
INTRODUCTION Biosphere pollution by heavy metals and nu-cleotides was accelerated dramatically during the last few decades due to mining, smelting, manufacturing, treatment of agricultural soils with agro-chemicals and soil sludge, etc. Problems associated with the contamination of soil and water such as animal wel-fare, health, fatalities and disruptions of natural eco-systems are well documented (He et al., 2005). Heavy metals such as Pb, Cr, As, Cu, Cd, and Hg, being added to our so…  相似文献   

12.
几种食用真菌对甘蔗渣利用的研究   总被引：1，自引：0，他引：1  
采用液体摇床发酵和固体平板培养技术,以甘蔗渣为唯一碳源,研究灵芝、大球盖菇、金针菇、柱状田头菇四种食用真菌对甘蔗渣的利用情况.测定在四种不同甘蔗渣含量的培养基中各食用真菌所产羧甲基纤维素酶活力和菌丝干重,同时测定了四种茵在平板上的菌丝生长速度.结果表明,灵芝在35g/L液体培养基中所产羧甲基纤维素酶活力最高达831U,所生长茵丝最重达1.162g.固体培养时,金针菇在30g/L生长速度最快达15mm/d.  相似文献   

13.
Students in a college nonscience majors' biology course took tests designed to reveal their conceptions of respiration and photosynthesis before and after course instruction. Even though most students had taken at least a full year of biology, serious misconceptions persisted. Most students gave definitions of respiration, photosynthesis, and food which were markedly different from those generally accepted by biologists. These incorrect definitions were associated with more fundamental misunderstandings about how plants and animals function. Most students could not explain how animal cells use either food or oxygen. They understood plants as vaguely analogous to animals, taking in food through their roots instead of mouths. Previous biology instruction seemed neither to improve student performance on the pretest nor to prepare them to master these conceptions during the course. Course instruction did improve student's understanding, but misconceptions persisted for many students. These results raise fundamental questions about the effectiveness of curriculum and instruction in current high school and college biology courses.  相似文献   

14.
Most of the literature dealing with effective teaching of adult students deals with particular teaching methods. As important as suchprocess suggestions are, it may be even more important to help adults find connections between thecontent of the disciplines and the issues they experience personally as they move through the life cycle. A discussion of ways to do this is provided by an interdisciplinary team. These ideas are then integrated into a view of the disciplines as a tool for helping students mediate course content as well as their life experiences in the service of learning and individual development.Dr. Charles S. Claxton is Associate Professor in the Department of Curriculum and Instruction and the Center for the Study of Higher Education. His major research interests include effective teaching of adults, student learning styles, and use of adult development theory to enhance the college curriculum. Dr. Susanne B. Darnell is Associate Dean of University College, a unit in which students design individualized baccalaureate degrees in professional or liberal studies. She was formerly a member of the Department of Sociology. Dr. Geneva B. Reid is an Instructor in the Department of English and has extensive teaching experience with traditional age and adult students. Dr. Cecil G. Shugart is Professor in the Department of Physics and has long been active in the American Association of Physics Teachers and the American Physical Society.  相似文献   

15.
It is of course very difficult to accurately project important characteristics of the future state of any rapidly evolving field, and the field of authoring systems for computer‐assisted instruction (CAI) is no exception. However, strong trends in evolving CAI systems of today would seem to indicate some important characteristics of the software systems underlying tomorrow's automated instructional systems. Under the premise that form follows function, this paper will explore the functional impetus of some of the most important trends extant in terms of their roots in a powerful, emerging technology of instructional design. This technology promises to complement the advancing hardware and software technologies, by supplying that sine qua non of successful instructional materials. It is inevitable that systems of the future will make (and indeed are making) significant accommodations of this vital technology as it matures, and therefore some important characteristics of tomorrow's systems can be predicated upon what is already known of this technology of instructional design.  相似文献   

16.
It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field inves- tigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order: feeding roots>stems≈main roots>old leaves>young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the above- ground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosyn- thetic rate, transpiration rate and biomass production of tea plants.  相似文献   

17.
This study is aimed at identifying and determining the percentage of occurrence frequency of cellulose decomposing soil fungi. The soil samples were inoculated into culture plates prepared in Sabouraud medium under sterilized conditions and incubated at 30 ℃ for 4 to 7 d. The identified fungal species were incubated in self-designed cellulose medium for testing their cellulolytic ability. Forty-two species, including2 nova species, representing sixteen genera showed growth and sporulation in the cellulose medium. Most of the isolated species were from genus Aspergillus and Penicillium. Aspergillus niger and Mucor hiemalis showed highest occurrence frequency （45% and 36% respectively）, as these species were collected from about 80% of soil samples. Being agar free and cheaper, the new fungal medium designed showed results equivalent to Sabouraud medium.  相似文献   

18.
The purpose of the study was to explore students’ alternative conceptions and their associative thinking regarding internal transport in plants through administration of a refined diagnostic test. Questions of associative thinking and explanation were added to form a third tier of the previous two-tier test. The study found three terms related to alternative conceptions: capillary action, minerals, and nutrients produced by photosynthesis. The students’ associative thinking related to these three terms suggested that: (1) capillary action is linked to a hair-water relation, (2) minerals are in the nutrients group, and (3) oxygen is linked to nutrients. Finally, issues regarding the impacts of language on conceptual learning are discussed under three strands: effects of language, Chinese language, and textbook language.  相似文献   

19.
研究目的：阐明水稻穗内不同粒位间的主要矿质营养元素和植酸含量差异、粒位分布特点及其与品种穗型间的联系。 创新要点：将水稻品种的穗型变化与稻米营养品质结合起来,从水稻穗粒结构角度,对同一稻穗内不同籽粒间的主要矿质营养元素与植酸含量差异、粒位分布特点及其与水稻品种穗型间的相互关系进行了较系统的探讨分析。 研究方法：以典型的直立穗型和弯穗型粳稻品种为材料,通过对两类水稻品种在相同栽培条件下籽粒矿质营养元素和植酸含量的测定分析,并依据水稻籽粒在稻穗上的着生部位,将同一稻穗内的不同籽粒划分为六个粒位,比较分析了两类品种同一稻穗内不同部位间矿质营养元素和植酸含量的差异变化及其粒位分布特点。 重要结论：水稻穗型虽然与品种问的籽粒矿质营养元素和植酸含量高低没有直接关系,但对其穗内不同籽粒间的主要矿质营养元素和植酸含量存在着较大影响;与稻穗中下部的弱势粒相比,同一稻穗内着生在稻穗上中部的强势粒通常具有相对较高的锌、铁矿质元素含量,而籽粒植酸含量和植酸,锌（铁）摩尔比则有所降低,稻米营养品质也相对较好;不同矿质营养元素相比,粒位效应对铁矿质营养的影响作用要略大于对钙和锌营养元素含量。  相似文献   

20.
内生真菌与牧草寄主形成互利的共生体,一方面植物为内生真菌提供光合产物和矿物质;另一方面内生真菌促进植物生长发育,增加了其抗逆性等．但是内生真菌可产生多种麦角生物碱,家畜采食这种牧草后,会产生中毒综合征,所以在未来的研究中应以创造有益的牧草一内生真菌共生体作为目标,从而提高牧草的应用价值．  相似文献   

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