Finite element method for eigenvalue problems in electromagnetics

Finite element method (FEM) has been a very powerful tool to solve many complex problems in electromagnetics. The goal of the current research at the Langley Research Center is to develop a combined FEM/method of moments approach to three-dimensional scattering/radiation problem for objects with arbitrary shape and filled with complex materials. As a first step toward that goal, an exercise is taken to establish the power of FEM, through closed boundary problems. This paper demonstrates the developed of FEM tools for two- and three-dimensional eigenvalue problems in electromagnetics. In section 2, both the scalar and vector finite elements have been used for various waveguide problems to demonstrate the flexibility of FEM. In section 3, vector finite element method has been extended to three-dimensional eigenvalue problems

A plant rhabdovirus associated with peanut veinal chlorosis disease in India

A disease of groundnut characterized by stunting of plants, veinal chlorosis, outward bending of leaflets and proliferation of axillary buds has been observed in several parts of Peninsular India since 1977. The disease was restricted to crops raised during the post-rainy season. A rhabdovirus was associated with this disease. This appears to be the first record of natural occurrence of a rhabdovirus in groundnut

Agronomic potential of A4(M) cytoplasmic male-sterility system compared to A1 CMS system of sorghum (Sorghum bicolor)

An investigation was carried out to compare the A4(M) CMS (cytoplasmic-nuclear male-sterility) system to the widely used A1 CMS system in sorghum (Sorghum bicolor (L.) Moench) for agronomic traits and panicle grain mold resistance (PGMR) score at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh, India in 2006 and 2007 rainy and postrainy seasons. The cytoplasm per se and its first order interaction with A-line seemed to contribute to grain yield, male-fertility restoration % and PGMR during rainy season and male-fertility restoration per cent during postrainy season. The mean days to 50% flowering, plant height and grain yield of A4(M) cytoplasm-based hybrids were comparable with those of A1 cytoplasm-based hybrids during 2006 and 2007 postrainy seasons while during 2006 rainy season, A4(M) cytoplasm based hybrids in few nuclear backgrounds were significantly superior to A1 cytoplasm based hybrids for early flowering and grain yield, while in few nuclear backgrounds A1 cytoplasm-based hybrids were superior. However, the A1 cytoplasm based hybrids were more tolerant for grain mold. Hence the A4(M) cytoplasm can be used to incorporate genetic diversity in grain sorghum hybrids for grain yield in postrainy season, but its use in rainy season is not recommended, where grain mold poses a proble

Indian Peanut Clump Virus Isolates: Host Range, Symptomatology, Serological Relationships, and Some Physical Properties

The symptomatology of Indian peanut clump virus (IPCV) isolates collected from five different geographical locations, Bapatla (B), Chinnaganjam (C), Hyderabad (H), Ludhiana (L), and Talod (T), differed. B-IPCV and C-IPCV were indistinguishable by host range but could be distinguished from the other isolates by symptoms on Canavalia ensiformis, Nicotiana clevelandii × glutinosa, Phaseolus vulgaris, and Vigna unguiculata. B-IPCV, C-IPCV, and T-IPCV were related serologically, but could be distinguished from H-IPCV and L-IPCV isolates in serological tests. The five isolates could not be distinguished on the basis of particle size. Each isolate contained two RNA species of 1.90 × 106 and 1.65 × 106 Mr estimated under nondenaturing conditions and a single polypeptide of 24 × 103 Mr. Significance of these findings for the diagnosis of IPCV and for screening of peanut genotypes for resistance is discussed

Peanut Chlorotic Streak Virus, a New Caulimovirus Infecting Peanuts (Arachis hypogaea) in India

Peanut (Arachis hypogaea [groundnut]) plants with reduced leaflets, chlorotic streaks, and stunting were observed during surveys for diseases caused by peanut viruses in India. These peanut plants were infected with a new caulimovirus designated peanut chlorotic streak virus (PClSV). PClSV was mechanically transmissible to several plants in Leguminosae and Solanaceae but was not transmitted by Aphis craccivora or Myzus persicae. Purified from Nicotiana clevelandii leaves, PClSV contained isometric particles 52 ± 3 nm in diameter. The virus was not related to cauliflower mosaic, figwort mosaic, or soybean chlorotic mottle viruses. Inclusion bodies similar to those produced by caulimoviruses were observed in the cytoplasm of infected Nicotiana rustica and A. hypogaea leaves. Purified PClSV contained two polypeptides with relative molecular masses of 58 and 51 kDa. The size of double-stranded DNA was estimated as approximately 8.1 kbp, which contained two single-stranded discontinuities. The physical map of the PClSV genome was distinctly different from those of other caulimoviruses

Evaluation of A1, A2, A3, A4(M), A4(G) and A4(VZM) cytoplasms in iso-nuclear backgrounds for grain mold resistance

Breeding for resistance to grain mold, an economically important disease of sorghum, has been only partially successful. Hybrid technology is well developed in sorghum due to availability of the cytoplasm male sterility (CMS) system and at present almost all commercial hybrids are based on the A1 CMS system. To compare the available alternate CMS systems for grain mold resistance, 72 hybrids were produced by crossing 36 A-lines (six CMS systems; A1, A2, A3, A4(M), A4(G), A4(VZM) each in six nuclear backgrounds) with two common restorers, and were evaluated during the 2006 and 2007 rainy seasons in grain mold nursery at ICRISAT. Data analyses indicated influence of cytoplasm on the responses of hybrids to grain mold infection as measured by panicle grain mold resistance (PGMR) score. The A1 cytoplasm seemed to contribute to grain mold resistance followed by A4(VZM) and A2 cytoplasms. The A4(M) cytoplasm had superior general combining ability (GCA) effects while the A1 and A4(VZM) cytoplasm based hybrids had superior specific combining ability (SCA) effects on the PGMR score. Almost all hybrids had significant mid-parent heterosis. The A1 cytoplasm is the best suited for the development of sorghum hybrids for the rainy season adaptation with grain mold resistance. However, use of alternate cytoplasms (A2 and A4(VZM)) for hybrid development will not increase susceptibility to grain mold in commercial grain production

Identification of Peanut Green Mosaic Virus Strains in India

During field surveys, three peanut green mosaic virus isolates differing in symptomatology on groundnut and a few other hosts were collected. Ultrathin sections of infected groundnut leaflets showed cytoplasmic inclusions with pin wheels and scrolls. In enzyme-linked immunosorbent assay they reacted strongly with antisera to peanut green mosaic and soybean mosaic virus antisera, and moderately with adzuki bean mosaic and peanut stripe virus antisera. All isolates also reacted positively with antisera to peanut eye spot, blackeye cowpea mosaic, pea seed-borne mosaic, potato virus Y and tobacco etch viruses, and did not react with antisera to peanut mottle, bean yellow mosaic, bean common mosaic, clover yellow vein and sugarcane mosaic viruses. SDS-PAGE analysis of purified virus preparations of the three isolates showed a single polypeptide with mol. wt. of 34,500 daltons. Based on these results, the three isolates are identified as biologically distinct strains of peanut green mosaic virus

Isolation and characterization of a potyvirus associated with bushy dwarf symptom in chickpea, Cicer arietinum, in India

A potyvirus that induced stunting and a characteristic bushy appearance at the apical region, due to proliferation of terminal branches with narrowed, reduced and deformed leaflets, was isolated from chickpea in India. The virus was sap-transmissible to 14 species of Chenopodiaceae, Leguminosae, Solanaceae and Malvaceae; Chenopodium amaranticolor was a good local lesion host. Virus particles, trapped by immunosorbent EM and stained with uranyl acetate, were 710±10 nm long. Purified virus preparations contained a single polypeptide species of 32 500 Da and one nucleic acid species of 3.1×106 Da. The virus was serologically related to soybean mosaic, azuki bean mosaic and peanut mottle potyviruses but not to clover yellow vein, pea seed-borne mosaic and bean yellow mosaic potyviruses. On the basis of these properties, the virus was identified as a previously undescribed potyvirus in chickpea, for which the name chickpea bushy dwarf virus is proposed

The occurrence of maize mosaic virus on sorghum in India

A leaf disease of sorghum (Sorghum bicolor) characterised by fine discontinuous chlorotic streaks between the veins, was observed on sorghum grown during the 1987/88 post-rainy season in peninsular India. Early-infected plants were stunted, had shortened internodes, and produced poorly developed panicles. The virus was transmitted by the delphacid planthopper, Peregrinus maidis. Negatively stained leaf dip preparations contained bullet-shaped virus particles (208 ± 4.4 × 66 ± 1.0 nm) resembling those of rhabdoviruses. In ultrathin sections, the particles budded through the inner nuclear membrane and were present in the cytoplasm within membrane-bound vesicles that were apparently contiguous with the distended outer nuclear membrane. A method for purifying the virus was developed utilising polyethylene glycol (PEG) precipitation, Celite filtration and sucrose densitygradient centrifugation. An antiserum was produced in rabbits with a titre of 1/2650 in the precipitin ring interphase test. The virus could be detected in infected sorghum leaf tissues using a direct antigen coating form of enzyme-linked immunosorbent assay (DAC-ELISA). In immuno-double diffusion tests, the virus reacted positively with antisera to maize mosaic virus (MMV) from Reunion (MMV-RN) and Hawaii (MMV-HI), but not with antisera to barley yellow striate mosaic (BYSMV), cereal chlorotic mottle (CCMV), and cynodon chlorotic streak (CCSV) viruses. Thus, the virus isolated from sorghum is designated the MMV-S isolate. In DAC-ELISA tests, MMV-S reacted positively with antisera to MMV-R, MMV-HI, MMV-Florida isolate, CCSV, and CCMV, and weakly with antiserum to BYSMV. SDS-polyacrylamide gel electrophoresis revealed four major proteins of relative mass Mr 70 000, 59 000, 32 000 and 28 000. In electro-blot immunoassay, MMV and CCSV antisera detected the G and N proteins. These data suggest that MMV-S should be placed in the sonchus yellow net virus subgroup of plant rhabdoviruse

Evaluation of Trait-based and Empirical Selections for Drought Resistance at ICRISAT Centre, Patancheru, Andhra Pradesh, India

The performance of 192 groundnut lines selected following trait-based and empirical selection approaches was evaluated in Patancheru, Andhra Pradesh, India, during 2000 rainy season and 2000/01 post-rainy seasons. In 2000 under irrigated conditions, the genetic variation for kernel yield, harvest index (HI), transpiration efficiency (TE) and transpiration were highly significant. The top 20 genotypes (kernel yield basis) consisted of 11 trait-based and 9 empirical selections. The variation between the genotypes and the parent with the best parent (ICGS 76) was not significant for all traits except transpiration, for which 4 genotypes showed superiority over ICGS 76. Under rainfed conditions, the top 20 genotypes consisted of 12 trait-based and 8 empirical selections. The variation between these genotypes and ICGS 76 was not significant except for TE, for which 4 genotypes were inferior to ICGS 76. In 2000/01 under irrigated conditions, the 20 top genotypes were not superior to ICGS 76 for all traits except HI, for which 7 genotypes (3 trait-based and 4 empirical selections) were superior to ICGS 76. Under mid-season drought conditions (irrigation was withheld from 40 to 80 days after sowing), the top 20 genotypes (12 trait-based and 8 empirical selections) did not significantly vary from ICGS 76 for all traits except HI, for which 7 genotypes showed superiority. Under all conditions, no selection method showed superiority in the selection of genotypes for kernel yield, HI, TE and transpiration. The combined analysis over all experiments indicated that 3 trait-based selections and one empirical selection for HI, and one trait-based genotype for transpiration showed significant gains ever ICGS 7