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31.
White grubs (larval scarabaeids) are now recognized as being important pests of groundnut (peanut) in many parts of the world because of their ability to damage roots. A method of simulating white grub damage to groundnut plants was developed to obtain an indication of how the feeding activity of these insects influences plant growth. The effect of root cutting and drought stress on water uptake and biomass production was evaluated, with roots being cut at three depths in the late vegetative and early podfilling stages. As groundnut plants are often grown under conditions of drought stress, the effects of which would be accentuated by root damage, this factor was introduced into the experiment. Plant water-use measurements indicated that the root systems of plants cut 30 days after emergence (DAE) and watered twice a week became fully functional again after 40 days. Pod and total biomass production were however significantly less than those of the uncut control plants, with drought stress reducing yields below the well-watered controls, particularly when cut at 10 cm below the soil surface. The root systems of plants cut 51 DAE did not regrow to any appreciable extent, and rates of plant water-use remained less than half of the uncut control plants. Over all treatments, there was a strong positive correlation between total (and pod) biomass and plant water-use. It was concluded that the phenological stage of the plant at which root damage occurred had a profound influence on the subsequent recovery in root growth and function, and ultimately on pod yield.  相似文献   
32.
Summary A method is described for rapidly screening the metabolic potential of bacteria to oxidize semivolatile and volatile compounds as a sole carbon source. The method is based on automated system that utilizes MicroplatesTM manufactured by Biolog, Inc. (Hayward, CA, USA). This system detects bacterial respiratory activity from the oxidation of a carbon source introduced in volatile form. This is in contrast to the original design, which is based on inoculating a carbon source directly into each well. The 96-well (MT) microtiter plates contain nutrients and a tetrazolium dye. When a bacterial species is capable of oxidizing a volatile carbon substrate, the dye turns purple, and a spectrophotometric plate reader quantifies the response. As a test of this method 150 isolates, including isolates known to degrade some of the test compounds and negative controls were evaluated for their potential to oxidize carbon tetrachloride, toluene, ando-xylene. Thirty-seven isolates (25%) were qualitatively identified as contaminant oxidizers, and thirteen of these (35%) showed significant degradation capabilities for both toluene ando-xylene.Environmental Sciences Division Publication Number 4277.  相似文献   
33.
不同产地苍术药材化学成分的比较   总被引:13,自引:2,他引:11  
江苏、安徽及湖北5个产地苍术(Atractylodeslancea(Thunb.)DC.)商品药材的化学分析结果表明:它们在某些药材性状、一些常规化学成分、挥发油成分和含量上存在显著差异。江苏茅苍术根茎挥发油的化学成分复杂,由此探讨了它作为地道药材的特殊性。同时对苍术的“断面暴露稍久可析出结晶”的性状和《药典》(1990年版)规定的“层析谱上应显有苍术素斑点”的鉴别实验进行讨论。  相似文献   
34.
A previous survey on pepper lines (Capsicum annuum L.) indicated that a susceptible cultivar, Yolo Wonder, reacted to cucumber mosaic virus (CMV) by producing a systemic yellow mosaic. By contrast, CMV caused no symptoms on lines Perennial and Vania. The virus is recoverable from the uninoculated leaves of Perennial, while in Vania CMV is restricted to the inoculated leaves. To interpret these phenomena, a comparative study on CMV multiplication rates, yield, specific infectivity and relative proportion of RNAs was made in the inoculated leaves of the three pepper varieties. The rate of CMV multiplication, as estimated by the double antibody sandwich form of enzyme-linked immu-nosorbent assay, was lower in Perennial than in Vania or Yolo Wonder. The yield of virus purified from Perennial was very low when compared with Vania or Yolo Wonder. The specific infectivity of the virus extracted from Perennial was less than that from Vania or Yolo Wonder. These results suggest that Perennial is resistant to CMV multiplication, while restriction of the virus in inoculated leaves of Vania is not due to the inhibition of the virus replication. However, polyacrylamide gel electrophoresis revealed that the RNA profiles of CMV purified from the three pepper lines were similar.  相似文献   
35.
Kutikova  L. A.  Markevich  G. I. 《Hydrobiologia》1993,255(1):545-549
Phylogenetic relations among the main groups of Monimotrochida are considered. The principal directions of monimotrochid evolution were defined by comparative investigations of mastax morphology (SEM), basic body structures, and general biology. On the basis of these results we propose a revision of previous rotifer taxonomy. We suggest to place the Monimotrochida in the order Protoramida divided into two suborders Flosculariina and Conochilina.  相似文献   
36.
Cancer is one of the main challenges of the health system around the world. This disease is increasing in developing countries and imposes heavy costs on patients and governments. On the other hand, despite various drugs, the death rate among cancer patients is still high and the current treatments have many harmful effects. In the traditional medicine of different countries, there are many medicinal plants that can be effective in the treatment of cancer. Ferula plants are traditionally used as spices and food or for medicinal purposes. Ferula assa-foetida is one of the famous plants of this genus, which has been used for the treatment of various diseases since ancient times. Among the main compounds of this plant, we can mention monoterpenes, sulfide compounds and polyphenols, which can show different therapeutic effects. This article has been compiled with the aim of collecting evidence and articles related to the anti-cancer effects of extracts, derived compounds, essential oils and nanoparticles containing Ferula assa-foetida. This review article was prepared by searching the terms Ferula assa-foetida and cancer, and relevant information was collected through searching electronic databases such as ISI Web of Knowledge, PubMed, and Google Scholar. Fortunately, the results of this review showed that relatively comprehensive studies have been conducted in this field and shown that Ferula assa-foetida can be very promising in the treatment of cancer.  相似文献   
37.
The geographical and bathymetric distribution of southern African octocorals is analysed. Of the over 200 estimated species of regional octocorals, 81 confirmed and adequately described species are studied using a radial sector method. Two primary faunal components are recognized–endemic (53.3% of the fauna by numbers of species) and Indo-Pacific (39.4%). An Atlantic component contributes only minimally (about 1.7%), while the remaining fauna is made up of cosmopolites (2.8%) and scattered species (2.8%). A subantarctic component is not evident for the present-day, although evidence for previous contact is presented. A sister-group analysis using genera as a guide to sister species, shows the biogeographic affinities for the present-day fauna as a whole to be 45% Indo-Pacific, 31% cosmopolitan, 10% endemic, 10% Atlantic and 4% southern oceans (subantarctic). Applying the same method to only those genera with endemic species shows the affinities of the present-day endemic fauna to be 27.5% Indo-Pacific, 27.5% endemic, 24% cosmopolitan, 14% Atlantic and 7% subantarctic. Clearly defined boundaries for west, south, and east coast faunas (as recognized by previous authors in describing various intertidal faunas) are found not be present with regard to the octocoral fauna (largely due to its overwhelmingly subtidal nature). Instead two primary zoogeographic provinces are recognized–the Cape Endemic Province (extending from Liideritz to Inhaca Island) and the south-western fringe of the Indo-Pacific Province from East London north-eastwards. An overlap zone between these two is recognized between East London and Inhaca Island, with the region in the vicinity of Richards Bay having an essentially evenly mixed fauna (roughly 50% Cape Endemic Province and 50% Indo-Pacific). Of the 84 octocoral genera recorded for the region, seven (or 8.3%) are endemic, and of these, five are monotypic while two are ditypic. The fauna is shown to be predominantly sublittoral (about 95% by numbers of species), the shallow sublittoral (< 100 m in depth) being the region with highest species richness. Pennatulaceans are eurybathic (intertidal to 4756 m) and clearly show a high proportion of cosmopolites (20% of presently identified species). Soft corals are stenobathic and restricted to the intertidal, continental shelf and uppermost portion of the continental slope (<500m), while gorgonians are intermediate in depth distributon (intertidal to 1200 m). No cosmopolitan alcyonaceans are presently recorded. The centre of the Cape Endemic Province is the Agulhas Bank–an extensive region of shallow continential shelf (< 200 m in depth) between Cape Town and East London. Two regions of octocoral radiation for southern Africa are postulated–the Agulhas Bank and the western Indian Ocean.  相似文献   
38.
关中小麦品种产量构成因素的相互关系和产量育种目标   总被引:7,自引:0,他引:7  
对关中地区不同年代及当前大面积推广的小麦品种(系)的产量及其构成因素进行了遗传分析和通径分析。结果表明:陕西关中地区近期小麦品种的产量育种目标的趋势是在提高现有穗粒数的基础上,保持现有的穗数(700万/hm^2)及千粒重(38g左右),以求在提高品种产量潜力的同时,保持或增加品种的稳定性能;或是大幅度提高穗粒数(35粒左右),适当提高千粒重(40g左右),适当降低穗数(600万/hm^2左右),以  相似文献   
39.
苦楝果实活性物质研究   总被引:7,自引:0,他引:7  
本文报道苦楝果实中的生物活性物质。发现果实的抽提物和单体化合物不仅具有防治作物害虫的作用,而且,还对植物有生长调节作用。通过生物活性鉴定结果表明:果实种仁的水抽提物对水稻早期萌动、发芽与秧苗的生长均有促进作用。其中,处理稻种第2天(48h),其发芽率比对照高出24.67%~42.86%;第4天秧苗的根长在1cm以上占56.5%~65.0%,而对照组只有15.5%。尤其是抽提液浓度在6000ppm时处理的稻种,测得生长10d的秧苗总长为对照的120.27%,胚根长为对照的121.54%;以及叶片中的叶绿素总含量比对照高8.5%。还证明了从果实中提取分离的几种三萜类化合物和在果实中发现的一种新化合物对苯二甲酸二甲酯,均对菜青虫有拒食和胃毒活性。  相似文献   
40.
The lateral leaflets of Desmodium motorium exhibit rhythmic upward and downward movements with a period in the minute range. Apoplasmic K+ and H+ activities were monitored in situ in the abaxial part of the pulvini with ion-selective microelectrodes. An extracellular electric potential was recorded simultaneously. The apoplasmic H+ activity of all pulvini exhibiting a regular rhythm of the extracellular electric potential oscillated with the same period between about 10 and 20 mM. The apoplasmic K+ activity was high when the membrane potential of the motor cells was depolarized (about 36 mV) and the cells were shrunken. In contrast, the apoplasmic K+ activity was low in the swollen state of the motor cells, when the membrane potential was hyperpolarized (about -136 mV). The volatile anesthetic enflurane suppressed reversibly the movement of the leaflets. The same treatment also arrested spontaneous oscillations in the apoplasmic K+ activity in the pulvinus. The apoplasmic K+ activity oscillated roughly in phase with the K+ activity between pH 6.6 and 6.0. Application of white light disturbed the rhythm and increased the extracellular pH. Our results indicate that the physiological mechanism that drives the lateral leaflet movements of Desmodium motorium is closely related to the osmotic motors mediating the leaf movements of Mimosa, Samanea and Phaseolus.Abbreviations Em membrane potential - Eex extracellular electric potential - Hex extracellular H+ activity - Kex extracellular K+ activity - Rex extracellular electrical resistance B. Antkowiak was supported by the Stiftung Volkswagenwerk.  相似文献   
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