bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epidemiology of groundnut rosette virus disease: current status and future research needs@
Authors: NAIDU R A , BOTTENBERG H. , SUBRAHMANYAM P. , KIMMINS F M , ROBINSON D J , THRESH J M 
Published: February 2008

SummaryRosette is the most destructive virus disease of groundnut in sub‐Saharan Africa. It is caused by a complex of three agents, namely groundnut rosette assistor virus, groundnut rosette virus and its satellite RNA. The disease appears to be indigenous to Africa as it has not been recorded elsewhere. Thus rosette represents a new‐encounter situation as the disease is thought to have spread to the introduced groundnut from indigenous host plants. Rosette has been known since 1907 and much information has been obtained on the main features of the disease, viz. its biology, transmission, viral aetiology and diagnosis, and the impact of chemical control of the aphid vector, cultural practices and virus‐resistant varieties on disease management. However, there are still many gaps in the available knowledge, especially the reasons for the large and unpredictable fluctuations in the incidence and severity of rosette disease throughout sub‐Saharan Africa. Three unresolved issues of particular importance concern the nature of the primary source(s) of inoculum, the means of survival of virus and vector during unfavourable periods, and the distances over which the aphid vector can disperse and disseminate virus. Now that the aetiology of the disease is understood and diagnostic tools have been developed, the time is opportune for new initiatives in understanding the ecology and epidemiology of rosette. Substantial progress can be made by developing a co‐ordinated multi‐disciplinary research programme and making full use of the latest techniques, approaches and experience gained elsewhere with other insect‐borne viruses. This information would help to explain the sporadic disease epidemics that cause serious crop losses and sometimes total crop failure, and would also facilitate the development of disease forecasting methods and sustainable integrated disease management strategies.
How predacious are predators? A study on Ocypus similis, a rove beetle of cereal fields
Authors: KROOSS STEFAN , SCHAEFER MATTHIAS 
Published: February 2008

Summary.It is attempted determine the diet breadth and to quantify the predator pressure byOcypus similis(F.) (Coleoptera: Staphylinidae), a dominant species of the rove beetle fauna in a winter wheat field. Laboratory and field experiments were conducted to determine the range of prey taxa and the consumption of a whole predator generation (including larvae) during its activity in the field. In laboratory experiments, adults and larvae ofO. similisfed on a variety of prey except spiders and larvae of soldier beetles (Cantharidae), but they preferred millipedes as food (Diplopoda: Julidae, Polydesmidae). This preference could also be observed in the field. Although the predator population reached its maximum density in April, highest predator pressure occurred in June because of high consumption rates during the second larval stage. Adult beetles and the individuals of the second larval stage contributed both about 1/3 to total population consumption. Predation by adult beetles was mainly restricted to early spring and summer while larval consumption was highest from April to July. The staphylinids reduced the population density of diplopods by 7–35%. Because millipedes are an important part of the decomposer community, predator activity may lead to a decrease of decomposition rates.
Resistance to sweet potato virus disease (SPVD) in wild East African Ipomoea
Authors: KARYEIJA ROBERT F , GIBSON RICHARD W , VALKONEN JARI P T 
Published: February 2008

Summary.Sweet potato virus disease (SPVD), the most harmful disease of sweet potatoes in East Africa, is caused by mixed infection with sweet potato feathery mottle potyvirus (SPFMV) and sweet potato chlorotic stunt crinivirus (SPCSV). Wild Ipomoea spp. native to East Africa (J cairica, I. hildebrandtii, I. involucra and J wightii) were graft‐inoculated with SPVD‐affected sweet potato scions. Inoculated plants were monitored for symptom development and tested for SPFMV and SPCSV by grafting to the indicator plant J setosa, and by enzyme‐linked immunosorbent assay (ELISA). Virus‐free scions of sweet potato cv. Jersey were grafted onto these wild Ipomoea spp. in the field, and scions collected 3 wk later were rooted in the greenhouse and tested for viruses using serological tests and bioassays. In all virus tests, J cairica and J involucra were not infected with either SPFMV or SPCSV. J wightii was infected with SPFMV, but not SPCSV, in the field and following experimental inoculation; J hildebrandtii was infected with SPCSV, but not SPFMV, following experimental inoculation. These data provide the first evidence of East African wild Ipomoea germplasm resistant to the viruses causing SPVD.
Direct PCR detection of phytoplasmas in experimentally infected insects
Authors: MARZACHI C. , VERATTI F. , BOSCO D. 
Published: February 2008

Summary.Phytoplasmas in leafhoppers have been detected by PCR using chrysanthemum yellows (CY)‐infected chrysanthemum as source plants, and two cicadellid Deltocephalinae species, Macrosteles quadripunctulatus and Euscelis incisus, as vectors. Three different primer pairs were used; two of these are universal and have been designed on conserved sequences of the 16S rRNA gene of phytoplasmas, and one was designed on extrachromosomal DNA of a severe strain of western aster yellows phytoplasma. They were used to amplify CY DNA obtained by two different extraction procedures; one was extraction with cetyl‐trimethyl‐ammonium‐bromide (CTAB), and the other was boiling in Tris‐EDTA buffer. The chromosomal primers amplified phytoplasma‐specific bands only from “CTAB” samples, while the plasmid primers were successful with both procedures. Amplification of phytoplasma DNA was possible from as little as 1/10000 of total DNA extracted from a single hopper. Failure to amplify phytoplasma DNA from insects stored at –20oC for 2 yr suggested that some kind of inhibition develops during long term tissue storage. Direct PCR appeared a very specific, sensitive and rapid method to detect phytoplasmas in fresh leafhoppers, provided that a proper combination of extraction and amplification procedures was used.
Modelling the predicted geographic and economic response of UK cropping systems to climate change scenarios: the case of sugar beet
Authors: DAVIES A. , JENKINS T. , PIKE A. , SHAO J. , CARSON I. , POLLOCK C J , PARRY M L 
Published: February 2008

Summary.Geographical changes in suitability for the cultivation of sugar beet in England and Wales were predicted for climate change scenarios for 2023 and 2065 by integrating a climate database (1951‐80) with climate‐driven crop growth models. Initially, the outputs were produced as point values (at meteorological site locations) of predicted potential yields for current production. The outputs were validated statistically using actual crop yield figures collated from bibliographic analysis. The most suitable model was run again incorporating projected temperature and precipitation changes for 2023 and 2065. The outputs were mapped using a Geographical Information System and used to predict possible economic changes in farm profitability (and general market trends). Results indicated that the area of suitability for the growth of the crop moves westward with an increase in production in the West Midlands of approximately 5% (2 t ha‐1 fresh weight) by 2023 and 13% (6 t ha‐1 fresh weight) by 2065. The reduction in production in East Anglia coupled with the increase in production in the West does not align well with the current location of processing factories
Inhibitory activity of Catharanthus roseus alkaloids on enzyme activity and reproduction in Euproctis fraternal (Lepidoptera: Lymantridae)
Authors: SUNDARI M S NALINA 
Published: February 2008

Summary.Studies on the effect of Catharanthus roseus alkaloids on the biology of Euproctis fraterna showed that at a dose of 10 ppm, only 19.25% fertile eggs were laid. The hatchability was totally suppressed at higher doses. There was a considerable reduction in total carbohydrate and protein content in treated larvae. The activity of digestive enzymes were also found to be inhibited.
Association of a phytoplasma with a yellow leaf syndrome of sugarcane in Africa
Authors: CRONJÉ C P R , TYMON A M , JONES P. , BAILEY R A 
Published: February 2008

Summary.Evidence is presented for the association of a phytoplasma, provisionally named sugarcane yellows phytoplasma (ScYP), in sugarcane affected by a yellow leaf syndrome. The phytoplasma was consistently detected in leaves of more than 40 varieties from eight African countries. It was present in all symptomatic as well as some asymptomatic field grown cane samples but not in plants grown from true seed, and it was also observed in phloem sieve tubes by transmission electron microscopy. Phytoplasma 16S rDNA was confirmed by PCR, and restriction fragment analysis using Rsal and Haelll confirmed that PCR‐amplified products were of phytoplasma rather than of plant or of other pathogen origin. Sequences obtained from the intergenic spacer region, between the 16S and 23S rDNA genes, confirmed the identity of the phytoplasma as belonging to the western X group of phytoplasmas.
Genetics of transgressive segregation for yield and yield components in wheat
Authors: YADAV B. , TYAGI C S , SINGH D. 
Published: February 2008

Summary.Three crosses of spring wheat (Triticum aestivum L. em Thell) involving six cultivars (WC29, WH291, SGP 14, RAJ. 1972, WH377 and HD 2329) were selected on the basis of combining ability analysis to study genetics of transgressive segregation for tillers/plant, grains/spike, 1000 grain weight and grain yield/plant using various mating designs. Diallel analysis indicated that both additive and non‐ additive components were significant for all the characters. On the basis of general combining ability and specific combining ability effects, the parents WH 291 and WH 377 were found to be good general combiners for tillers/ plant, 1000 grain weight and grain yield/plant. For grains/spike SGP 14 was found to be a good general combiner. The cross WH 377 × HD 2329 for tillers/plant, SGP 14 × Raj. 1972 for grains/spike and grain yield/plant and WC 29 × WH 291 for 1000 grain weight were found to be good cross combinations. Generation mean analysis indicated that the additive‐dominance model was inadequate for all the characters in all the crosses except for 1000 grain weight in WC29 × WH291. Additive component was more pronounced than non‐additive components for all the characters in all the crosses except for tillers/ plant in WH 377 × HD 2329.Predictions for transgressive segregants from F3 was more accurate than that from generation mean analysis. However, prediction from both the sources were equally efficient if additive‐dominance model was adequate. In general, observed frequencies of transgressive segregants were more in F2 and BIPi than F4 but the majority of them were discarded on progeny testing. Biparental mating had an impact in increasing the frequencies of transgressive segregants for different characters in all the crosses. The crosses, WH 377 × HD 2329 for grain yield/ plant, SGP 14 × Raj. 1972 for tillers/plant and WC 29 × WH 291 for grains/spike and 1000 grain weight were found to be potential crosses for transgressive segregants. A comparison of combining ability of parents and crosses, and observed and predicted frequencies of transgressive segregants indicated that the potential crosses for transgressive segregants were those that had high sea effects and involved high and low general combiners. The crosses involving low general combiners irrespective of their sea effects showed poor performance with respect to transgressive segregation.
Combining ability of biomass and harvest index under short‐ and long‐day conditions in groundnut
Authors: DWIVEDP S L , NIGAM S N , CHANDRA S. , RAMRAJ V M 
Published: February 2008

Summary.Photoperiod insensitivity plays a significant role in ensuring wide adaptability of genotypes across environments. The effect of photoperiod in groundnut (Arachis hypogaea L.) is manifested in post‐flowering development including partitioning. The partitioning of assimilates, as measured by harvest index (HI), has the greatest effect on pod yield. The Fi progenies (excluding reciprocals) and their parents from a six‐parent diallel cross were studied to estimate combining ability for biomass and HI under short (SD)‐ and long (LD)‐day conditions, and to identify good combiners with high biomass and HI for use in breeding programmes. The experiment was conducted for three seasons in a split plot design with two photoperiods as main plots and 21 genotypes as subplots. The two photoperiod treatments were SD defined as normal‐day light period and LD defined as normal‐day light period extended by 4 h using incandescent lamps. The multi‐environment analogue of Griffing's Method 2 ‐ Model 1 was modified to analyse data for combining ability. While biomass was controlled by both GCA and SCA effects, HI was predominantly controlled by GCA effects. GCA and SCA effects for biomass and HI interacted with environments (six factorial combinations of photoperiods and seasons). SCA effects remained insensitive to variation in photoperiod both for biomass and HI. However, GCA effects for HI were sensitive to photoperiod. V6 (ICG 2405) was a good general combiner for both biomass and HI across environments. None of the crosses showed positive and significant SCA effects for both biomass and HI. Photoperiod influenced the sensitivity of GCA effects of V2 (ICGV 86694) and V6 for HI. However, the difference between SCA effects of V2 × V6 was not significant. The results of this study emphasise the need for future experiments with random genotypes over a range of photoperiods.
The effect of sodium chloride on the Ca2+, K+ and Na+ concentrations of the seed coat and embryo of Acacia tortilis and A. coriacea
Authors: REHMAN S. , HARRIS P J C , BOURNE W F 
Published: February 2008

Summary.The uptake of Na+ and the loss of Ca2+ and K+ by seeds of Acacia tortilis (Forsk.) Hayne (salt tolerant) and A. coriacea DC. (salt sensitive) were determined after 24 h soaking in 250 mol m‐1,3 NaCl or in distilled water. Na+ uptake was higher by the seed coat than by the embryo of both species and higher by A. coriacea than by A. tortilis. The greater Na+ uptake by A. coriacea was associated with greater Ca and K+ leakage. The Na+ concentration of solution imbibed by the embryo of both species was lower than the Na+ concentration in the external solution, indicating an exclusion of Na+. When A. tortilis and A. coriacea seeds were treated with a series of NaCl concentration (0–400 mol m‐1,3), the exclusion mechanism was particularly clear with A. tortilis at lower concentrations (50 and 150 mol m‐1,3) of NaCl. In contrast, the seed coat of both species accumulated Na+. Thus the seed coat may play an important role in ion exchange. These results show that it is important to consider the seed coat and embryo separately rather than the whole seed when considering ion exchange in relation to salinity tolerance.
A growth stage key for winter linseed (Linum usitatissimum)
Authors: SMITH J M , FROMENT M A 
Published: February 2008

Summary.A growth key for use in winter linseed Linum usitatissimum is described. The decimal key is based upon the principles outlined by the BBCH scale. This scale covers the following main development stages in winter linseed: germination and emergence, leaf development, basal branching, stem extension, inflorescence development and emergence, flowering and capsule formation, development of the seed and capsule, capsule and seed ripening and stem senescence. These are subdivided into secondary stages. The key aims to provide farmers and advisers with clear guidance on appropriate growth stages for treatment of winter linseed crops and its' use is discussed with particular reference to agro‐chemicals. Botanical illustrations are presented, based on samples taken from winter linseed crops covering the main growth stages.
Periderm cell size as a ploidy indicator in potato (Solatium tuberosum L. subspecies tuberosum)
Authors: DE M J 
Published: February 2008

Summary.Using the tubers of glasshouse‐grown potato plants, periderm cell dimensions were found to indicate ploidy in comparisons of Solanum tuberosum subspecies tuberosum dihaploids and their somatically‐chromosome‐doubled derivatives. The mean ratio of dihaploid to tetraploid cell sizes, determined as the product of cell length x breadth, was 0.60:1.There were differences between 34 tetraploid cultivars in their mean periderm cell sizes and between clones within six dihaploid families derived parthenogen‐etically from tetraploids. There was variation in mean cell size but dihaploid cells were always smaller than those of their parents. The mean cell size of the parent was usually in the next highest size class of its largest‐celled dihaploids.As there was overlap between dihaploid and tetraploid ranges it was concluded that in order to identify dihaploids the mean cell size in tubers of the parent grown under the same conditions should be used for comparison. Clones with mean periderm cell sizes no greater than 60% of the parent's cell size could be provisionally classed as dihaploid.
Methods for assessment of light leaf spot (Pyrenopeziza brassicae) on winter oilseed rape (Brassica napus) in the UK
Authors: FITT B D L , DOUGHTY K J , GILLES T. , GLADDERS P. , STEED J M , SU H. , SUTHERLAND K G 
Published: February 2008

Summary.Light leaf spot(Pyrenopeziza brassicae)was assessed as % plants with light leaf spot, % leaves with light leaf spot or % leaf area with light leaf spot in winter oilseed rape field experiments done at different sites (Rothamsted, Hertfordshire; Boxworth, Cambridgeshire; near Aberdeen, Scotland), with different cultivars (e.g. Bristol and Capitol), different fungicide treatments, on plants sampled at different dates. Regression analyses on data from these experiments showed that there were consistently good relationships between % leaves with light leaf spot and % plants with light leaf spot for plants sampled during the autumn and winter, until the % plants with light leaf spot approached 100%. The slopes and positions of regression lines were sometimes affected by cultivar, fungicide treatment or sampling date, but not by site. The relationship between%leaf area with light leaf spot (square root‐transformed) and % leaves with light leaf spot was less consistent than that between % leaves with light leaf spot and % plants with light leaf spot and was sometimes affected by cultivar, fungicide treatment or sampling date but not by site. The relationship between % leaf area with light leaf spot (square root‐transformed) and % plants with light leaf spot was also inconsistent and was sometimes affected by cultivar, fungicide treatment, sampling date and site.
The effect of treating seed potato tubers with benzimidazole, imidazole and phenylpyrrole fungicides on the control of rot and skin blemish diseases
Authors: CARNEGIE S F , CAMERON A M , LINDSAY D A , SHARP E. , NEVISON I M 
Published: February 2008

Summary.Over 6 yr the effectiveness of imazalil, prochloraz and fenpiclonil, applied either alone or in a mixture, in controlling gangrene, dry rot, skin spot and silver scurf on potato tubers in store was compared with that of 2‐aminobutane and thiabendazole. An assessment was also made of their efficiency in controlling the development of these diseases on the daughter tubers of seed tubers treated at harvest or before planting.Overall, 2‐aminobutane was more effective in controlling gangrene (Phoma foveata) in store than the spray‐applied fungicides. Deposits of imazalil, thiabendazole and fenpiclonil were greater when sprays were applied with an electrostatic sprayer than with a hydraulic sprayer. The opposite was found with the mixture of prochloraz Mn and tolclofos‐methyl. More effective gangrene control was associated with the highest deposits. Fenpiclonil and the mixture of thiabendazole and imazalil were more effective in controlling dry rot (Fusarium solani var. coeruleum) than imazalil alone. The development of dry rot was, however, increased by 2‐aminobutane treatment on eight out of 14 stocks. 2‐aminobutane gave the greatest reduction (83%) in the severity of skin spot during storage whereas thiabendazole alone, and the mixture of thiabendazole and imazalil, gave mean reductions of 70% and 65% respectively. This mixture and fenpiclonil gave the greatest reduction in the severity of silver scurf although, in general, reductions in silver scurf with fungicide treatment were less than with skin spot. The type of sprayer used to apply a fungicide did not affect the effectiveness of the fungicides in controlling either skin spot or silver scurf on tubers in store, or on the daughter tubers.The incidence of gangrene and dry rot on daughter tubers was not reduced consistently by fungicide treatment of seed tubers of the six stocks tested. However, the severity of skin spot and silver scurf was reduced by fungicide treatments of all eight stocks but the reduction in disease was greater for skin spot than for silver scurf. All fungicides gave reductions in the severity of skin spot, and fenpiclonil and the mixture of thiabendazole and imazalil were the most effective for silver scurf. The effectiveness of the fungicides in controlling these diseases was similar for seed treated at harvest and that treated before planting.
Temporal spread of cassava mosaic virus disease in a range of cassava cultivars in different agro‐ecological regions of Uganda
Authors: OTIM‐NAPE G W , THRESH J M , BUA A. , BAGUMA Y. , SHAW M W 
Published: February 2008

Summary.The spread of cassava mosaic disease (CMD) in a range of cassava cultivars was studied in experiments and on‐farm trials in different agro‐ecological regions of Uganda in 1989–1990 and 1990–1991. No spread occurred in either experiment at the southernmost site near Kampala, but there was considerable spread at the four sites elsewhere and also in the on‐farm trials in Luwero district. There were significant differences in the final incidence of disease between locations and between cultivars at each location. Where spread occurred it was more rapid in the Ugandan cvs Ebwanateraka, Senyonjo and Bao than in four of the five improved TMS cultivars introduced from Nigeria. These usually showed an apparent decline in incidence of CMD after reaching maxima 4 to 8 months after planting (MAP). The areas under the disease progress curves (AUDPCs) differed significantly between locations and cultivars and were less for cvs TMS 30572, TMS 30395, TMS 30337 and TMS 60142 than for cvs Ebwanateraka, Senyonjo, Bao and TMS 30786. Overall, the mean AUDPCs were greatest at Migyera in Luwero district in 1989–1990 and at Kagando in Kasese district in 1990–1991. They were significantly less at Mubuku in Kasese district in 1989–1990 than at the other two experimental sites where spread occurred. Adult whitefly vector populations were highest at Migyera and Kagando in the 1989–1990 and 1990–1991 trials, respectively, and they were higher on cvs Bao, Ebwanateraka and TMS 30786 than on other varieties. Mean numbers of adults increased until 3–5 MAP and then declined, but CMD incidence increased progressively to reach maxima at or near crop maturity. Locations with the largest numbers of adults also had a relatively high incidence of CMD. Symptoms of CMD were usually more severe on cvs Ebwanateraka, Bao and Bukalasa 11 than on the TMS cultivars, on which symptoms remained slight throughout growth and usually decreased from 5 MAP. The differences between sites, the resistance of the cultivars and the relationship between CMD incidence and whitefly populations are discussed.