Use of egg yolk in seromonitoring against newcastle disease     

Parimal Roy  S. Anandan  G. Ravikumar  A. Koteeswaran  A. T. Venugopalan 《Tropical animal health and production》1997,29(4):245-246

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Indentification of true genetic dwarfing sources in foxtail millet (Setaria italica Beauv.)     

S. P. Dineshkumar  V. R. Shashidhar  R. L. Ravikumar  A. Seetharam  B. T. S. Gowda 《Euphytica》1992,60(3):207-212

Summary True genetic dwarfs hither-to not reported have been located in foxtail millet. The dwarfs as a group distinguished themselves from the talls in having altered constellation of characters. The morphological differences were highly significant for plant height, internodal length, and tillering potential. The talls had elongated internodes compared to dwarfs while there was no difference for node number on the main stem suggesting that short internodal length was primarily responsible for dwarfism. The dwarfs also showed slightly higher leaf number per plant, leaf area and harvest index compared to talls. The dwarfs were insensitive to exogenous GA₃ application indicating that GA₃ synthesis is not impaired. This suggests that dwarfing gene sources presently identified are true genetic dwarfs and their behaviour is similar to dwarfs derived from Norin 10 in wheat and Dee-geo-woo-gen in rice. The superior morphological frame makes these dwarfs ideal as far as plant type is concerned and offers immense potentialities in breeding high yielding foxtail millets.  相似文献   

Evaluation of fertigation scheduling for sugarcane using a vadose zone flow and transport model   总被引：1，自引：0，他引：1  

V. Ravikumar  G. VijayakumarJ. Šim?nek  S. ChellamuthuR. Santhi  K. Appavu 《Agricultural Water Management》2011,98(9):1431-1440

Micro-irrigation has become an optimal means for providing water and nutrients to crops. There is an ample space for improving fertilizer use efficiency with micro-irrigation, if the movement and reactions of fertilizers in the soil are well understood. However, the rhizosphere dynamics of nutrients is very complex, depending on many factors such as soil temperature, pH, water content, and soil and plant characteristics. Many factors cannot be easily accurately quantified. However, using state-of-the-art modelling techniques, useful and reliable information can be derived.An attempt was made to evaluate the reactive transport of urea in the root zone of a sugarcane crop under drip irrigation, and to quantify the fluxes of urea, ammonium, and nitrate into the crop roots, volatilization fluxes, and deep drainage using a numerical model. This quantification helped in designing an optimal fertigation schedule. Various parameters used in the model were taken from either the literature or the field study. A typical scenario, based on the recommended total quantity of urea for sugar cane crop under drip irrigation in India, was tested using HYDRUS-2D. The total amount of urea was divided into fortnightly doses, depending on the stage of crop growth. For this scenario, the modelled crop uptake was found to be 30% higher than the crop demand. Consequently, an optimal fertigation schedule was developed that reduced the use of urea by 30% while at the same time providing enough N for its assimilation at all stages of crop growth. This type of modelling study should be used before planning field experiments for designing optimal fertigation schedules.  相似文献   

Selection of efficient arbuscular mycorrhizal fungi in the rhizosphere of cashew and their application in the cashew nursery     

G. Ananthakrishnan  R. Ravikumar  S. Girija  A. Ganapathi 《Scientia Horticulturae》2004,100(1-4):369-375

Mycorrhizal association in cashew (Anacardium occidentale L.) grown in five different plantation areas of South India was investigated. The soil samples were collected from all locations. Physico-chemical properties of rhizosphere soils, arbuscular mycorrhizal fungal spore count and root colonization were recorded. Species isolated were Acaulospora, Gigaspora, Glomus and Scutellospora. The mycorrhizal spore density was maximum at Thanjavur and minimum at Kudumiyamalai. Root colonization percentage oscillated between 20 and 30%. The species of Glomus, G. aggregatum Schenck and Smith, G. fasciculatum (Thaxter) Gerdemann and Trappe and G. mosseae (Nicol. and Gerd.) Gerdemann and Trappe were the most abundant in the majority of the experimental sites. Hence these three species were selected and used for artificial inoculation studies. Of the three mycorrhizal fungi G. fasciculatum significantly increased shoot length, internode number, internode length, number of leaves, stem diameter, root length and root number.  相似文献   

Gametophytic selection for wilt resistance and its impact on the segregation of wilt resistance alleles in chickpea (Cicer arietinum L.)     

R. L. Ravikumar  G. N. Chaitra  Anilkumar M. Choukimath  C. D. Soregaon 《Euphytica》2013,189(2):173-181

In the present study, the effect of gametophytic selection on the segregation of molecular markers linked and unlinked to wilt resistance loci was investigated. A homozygous resistant genotype WR315 (h₁h₁ h₂h₂) was crossed to two susceptible lines, Karikadle (H₁H₁ H₂H₂) and BG256 (h₁h₁ H₂H₂), to generate two different F₁ populations. Three F₁ plants from each cross were subjected to gametophytic selection by spraying a pathotoxin at flower bud initiation stage, while the remaining F₁ plants in each cross were treated as control by spraying them with water. Both control and treated F₁ plants were selfed to generate respective F₂ populations. The seeds of control and selected F₂ populations of both crosses were sown to raise the plants. The DNA from 60 to 70 plants in each treatment group were isolated and tested for presence of the markers linked and unlinked to wilt resistance loci. Both the linked and unlinked markers showed expected monogenic ratio of 3:1 individually in control population. In the selected F₂ population the markers CS 27₇₀₀ linked to H₁ locus, A07C₄₁₇ and H₄G₁₁ linked to H₂ locus of wilt resistance exhibited significant deviations for monogenic and digenic ratios. The unlinked markers NCPGR93 and NCPGR48 showed expected monogenic ratios in the selected F₂ population. The results demonstrated that the gametophytic selection for wilt resistance increase the frequency of resistance alleles and resistant plants in the progeny. Deviation from the expected segregation ratio of the marker closely linked to resistance loci suggests the presence of linkage drag in gametophytic selection for resistance. The significant deviation from monogenic ratio was also observed for the linked marker A07C₄₁₇ in the selected F₂ population of second cross BG256 × WR315. On the contrary, the segregation of markers in a different linkage not linked to resistance loci was not affected. Thus demonstrating the utility of gamete selection for resistance is increasing the frequency of resistant plant in the progeny independent of the parental genotype. Gametophytic selection can be applied in plant breeding programmes to develop wilt resistant genotypes in a short period.  相似文献   

Development of ITS sequence based molecular marker to distinguish, Tribulus terrestris L. (Zygophyllaceae) from its adulterants     

Subramani Paranthaman Balasubramani  Ramar Murugan  Kaliamoorthy Ravikumar  Padma Venkatasubramanian 《Fitoterapia》2010

Tribulus terrestris L. (Zygophyllaceae) is one of the highly traded raw drugs and also used as a stimulative food additive in Europe and USA. While, Ayurvedic Pharmacopoeia of India recognizes T. terrestris as Goksura, Tribulus lanuginosus and T. subramanyamii are also traded by the same name raising issues of quality control. The nuclear ribosomal RNA genes and ITS (internal transcribed spacer) sequence were used to develop species-specific DNA markers. The species-specific markers efficiently amplified 295 bp for T. terrestris (TT1F and TT1R), 300 bp for T. lanuginosus (TL1F and TL1R) and 214 bp for T. subramanyamii (TS1F and TS1R). These DNA markers can be used to distinguish T. terrestris from its adulterants.  相似文献   

Drought tolerance in sorghum by pollen selection using osmotic stress   总被引：2，自引：0，他引：2  

R.L. Ravikumar  B.S. Patil  P.M. Salimath 《Euphytica》2003,129(3):371-376

A pollen selection study for drought tolerance using Poly Ethylene Glycol (PEG) as a selective agent was conducted in sorghum. Ten genotypes of sorghum suitable for post rainy season were crossed to cytoplasmic male sterile line 104A and three genotypes to 116A producing 13 hybrids. Two sets of 13 hybrids with and without pollen selection were produced. PEG at 36 per cent was applied to stigma and stylar tissue one hour before pollination for pollen selection (selective fertilization) and no treatment for control (nonselective fertilization). Hybrids thus produced through selective and non-selective fertilization were tested in moisture stress environment during post rainy season. The hybrids obtained through selective fertilization produced significantly higher mean grain yield compared to hybrids obtained through non-selective fertilization. The results indicate that selective fertilization through in vivo pollen selection using PEG as selective agent was effective in improving moisture stress tolerance of the progeny in sorghum genotypes studied. Further, the pollen selection also had influence on plant height, panicle length, panicle width, panicle weight and grain mass. Thus,the pollen selection had a significant effect on grain yield through its components and developmentally related traits. Pollen selection for osmoticstress tolerance in sorghum influences the growth and vigour of the plants resulting in superior progeny in moisture stress environment. The analysis of individual crosses indicated that pollen genotype selection was able to favour performance of the progeny. However, the pollen selection had positive effect in majority of the hybrids and the study demonstrates the transmission of the selected trait from pollen generation to progeny. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Efficacy of non-toxic surfaces to reduce bioadhesion in terrestrial gastropods     

Kennedy AJ  Vasudevan R  Pappas DD  Weiss CA  Hendrix SH  Baney RH 《Pest management science》2011,67(3):318-327

BACKGROUND: Invasive species are described as the greatest threat to biodiversity, after habitat destruction and climate change, potentially imposing economic impacts and indigenous species impairment. Commonly applied chemical controls present the potential for legacy contamination and non‐target organism injury. This study investigated the effects of different substrates and novel topographical surfaces on the behavioral and mechanical associations of the terrestrial gastropod Otala lactea. RESULTS: The gastropod preferentially aestivated on rough glass (61% increase, P < 0.01) relative to smooth glass but avoided a cross‐patterned surface tessellation on silicone (82% reduction, P < 0.01) relative to smooth silicone. Significant deviations in turning behavior were found on the cross‐patterned topographical surface and hydrophobic Teflon surfaces. The strongest correlation with gastropod adhesion strength to surfaces was found for surface elastic modulus (R = 0.88, P = 0.03), followed by hydrophobicity (R = ? 0.71, P = 0.14), but no relationship with roughness (P = 0.36). CONCLUSION: Preliminary data suggest surface roughness controlled aestivation behavior while elastic modulus (surface flexibility) controlled adhesion strength. In spite of greater adhesion to high‐modulus materials, surface modulus was not a statistically significant controlling factor on gastropod aestivation preference. Understanding and exploiting the behavioral and mechanistic cues that organisms use while attaching to surfaces may lead to more environmentally benign control approaches. Published 2010 by John Wiley & Chemical Industry  相似文献   

家蚕AFLP分子进化研究     

周泽扬  李斌  G.Ravikumar  全国兴  田村俊树 《西南农业学报》2004,17(2):240-243

为进一步探讨家蚕的起源分化和其系统发育，为家蚕遗传育种提供科学依据，利用AFLP技术和统计学分析对具有代表性的9个不同的地区家蚕品种进行了分子系统学研究。家蚕的DNA多态性分析及其聚类分析结果进一步证实家蚕可能起源于不同地方(多起源中心)、由多种生态类型(包括一化、二化、多化)混杂的野桑蚕驯化而来，其驯化之初就已拥有一化、二化、多化的遗传背景，而且一化和二化品种间的遗传距离小，分化程度小，表明它们应该有共同的起源中心。  相似文献   

Direct Determination of Grain Boundary Atomic Structure in SrTiO3     

McGibbon MM  Browning ND  Chisholm MF  McGibbon AJ  Pennycook SJ  Ravikumar V  Dravid VP 《Science (New York, N.Y.)》1994,266(5182):102-104

An atomic structure model for a 25 degrees [001] symmetric tilt grain boundary in SrTiO(3) has been determined directly from experimental data with the use of high-resolution Z-contrast imaging coupled with electron energy loss spectroscopy. The derived model of the grain boundary was refined by bond-valence sum calculations and reveals candidate sites for dopant atoms in the boundary plane. These results show how the combined techniques can be used to deduce the atomic structure of defects and interfaces without recourse to preconceived structural models or image simulations.  相似文献