bluuebunny/crossref_metadata_2025 huggingface dataset:
Classification of genetic diversity in Abelmoschus tuberculatus germplasm collection using morphometric data
Authors: BISHT I S , PATEL D P , MAHAJAN R K
Published: February 2008

Abelmoschus tuberculatus Pal & Singh is endemic to India and is the close relative of cultivated okra, A. esculentus. Data on 49 selected accessions of A. tuberculatus were used to study genetic diversity for a range of morphological characters through the use of multi‐variate statistics. Epicalyx segments, shape, size and persistence; petal colour and petal blotch; stem and fruit pubescence; pigmentation of various plant parts; days to flowering; plant height; and the fruit yield/plant were the important components of variation and contributed significantly to the total variation in germplasm accessions under study. The accessions could be grouped into four distinct clusters. The grouping pattern, however, did not reflect relationship between geographic origin and genetic diversity. The potential use of the variability in okra improvement programmes is discussed.
Developmental threshold, day‐degree requirements and voltinism of the aphid predator Episyrphus balteatus (Diptera: Syrphidae)
Authors: HART A J , BALE J S , FENLON J S
Published: February 2008

Episyrphus balteatus is the dominant syrphid predator of aphids in the UK, reestablishment of populations each season is mainly by migration from warmer climes, as overwintering in this country is minimal with an uncertain level of success. The effects of temperature on the developmental rate of E. balteatus were investigated to determine the potential voltinism of this species in the UK. Estimates of the developmental threshold temperature from oviposition to adult emergence varied between 6.0d̀C and 7.1d̀C with a day‐degree (DD) requirement of between 256 and 280 depending on the method of analysis used. Using the DD requirement derived from a weighted linear regression (261 DD above a threshold of 6.8d̀C) in combination with the required value from adult emergence to first oviposition, suggests a total requirement of approximately 374 DD above 6.8d̀C per generation. These data, together with climate records, indicate that one to three generations are possible each year, depending on the available DD and origin of the population. The advantages and limitations of different approaches and models used to estimate developmental thresholds and DD requirements are discussed.
Distribution of Burkholderia cepacia phenotypes by niche, method of isolaiton and pathogenicity of onion
Authors: YOHALEM DAVID S. , LORBEER JAMES W.
Published: February 2008

Several proposals have been made for the subdivision of the bacterial species Burkholderia cepacia. Data applying these schemes to a collection of 188 strains of B. cepacia, isolated using a variety of methods, from soils, decayed onions, and nosocomial sources are presented. None of the schemes could be shown to be associated with the method of isolation, niche from which a strain was isolated, pectolytic activity, or pathogenicity to onion. Strains isolated by serial dilution on onion slices were much more uniform than were strains isolated using semiselective media. The nutritionally stringent medium of Lumsden and Sasser (US Patent No. 4 588 584) was judged better for the collection of a phenotypically broad sample of B. cepacia than those of Hagedorn, Gould, Bardinelli & Gustavson (1987) and Wu & Thompson (1984), which are based on antibiotic insensitivity. Pectolytic activity and pathogenicity to onion were shown to be highly correlated characters. None of the strains of clinical origin was capable of macerating onion tissue.
Apparent absence of viruses in most symptomless field‐grown sweet potato in Uganda
Authors: GIBSON R W , MWANGA R O M , KASULE S. , MPEMBE I. , CAREY E E
Published: February 2008

Symptomless sweet potato (Ipomoea batatas) plants obtained from farmers' fields in each of the main sweet potato growing regions of Uganda were tested by nitro‐cellulose membrane enzyme‐linked immunosorbent assays (NCM‐ELISA) for sweet potato feathery mottle virus (SPFMV), sweet potato mild mottle virus (SPMMV), sweet potato chlorotic fleck virus (SPCFV), sweet potato latent virus (SPLV), C‐6 virus (C‐6) and sweet potato caulimo‐like virus (SPCa‐LV). Most of the plants tested gave negative reactions in all NCM‐ELISA, only c. 5% giving positive reactions to SPFMV and c 1% to SPMMV or SPCFV. Graft inoculations of cuttings from symptomless sweet potato plants, obtained either at Namulonge Agricultural and Animal Production Research Institute (NAARI) or from farmers' fields, onto seedlings of the near‐universal indicator plant for sweet potato viruses, Zpomoea setosa, caused symptoms in c. 15% of indicator plants; in all such cases, SPFMV alone was identified by NCM‐ELISA. Supplementary tests, involving further grafting of sweet potato to I. setosa seedlings or grafting sweet potato plants themselves with sweet potato sunken vein virus (SPSVV), which in the presence of SPFMV causes sweet potato virus disease (SPVD), confirmed the absence of infection in sweet potato cuttings which had not caused symptoms on I. setosa in the initial graft test. Possible mechanisms explaining the prevalence of virus‐free sweet potato plants in farmers' fields are discussed.
Occurrence of papaya ringspot potyvirus and cucurbit viruses in Nepal
Authors: DAHAL G. , LECOQ H. , ALBRECHTSEN S E
Published: February 2008

A survey of papaya and 10 cucurbitaceous vegetables (ashgourd, zucchini, watermelon, cucumber, pumpkin, bottlegourd, snakegourd, spongegourd, bittergourd and choyote) during 1989 and from 1992 to 1994 in more than 68 locations (both experimental plots and farmers' fields) covering 18 terai and inner‐terai districts of Nepal, indicated that these crops were heavily affected with various virus‐like symptoms. The most commonly observed symptoms were severe mosaic, leaf distortion, oily streaks or spots on papaya; leaf distortion, blisters and shoe stringing on zucchini; and mosaic or yellow mosaic, blisters, and leaf distortion on other cucurbits. Average incidence of plants with symptoms ranged from 75% to 100% on papaya; 85% to 100% on zucchini; 4% to 100% on cucumber; 4% to 100% on pumpkin and 10–100% on bottlegourd, choyote and watermelon. The virus isolated from papaya and zucchini was confirmed as papaya ringspot potyvirus — watermelon strain (PRSV‐W). It was also detected in survey samples from ashgourd, bittergourd, snakegourd, spongegourd, zucchini, watermelon, bottlegourd and cucumber. Leaf extracts of some cucumber, choyote, pumpkin, zucchini and snakegourd samples reacted with cucumber mosaic cucumovirus (CMV) and zucchini yellow mosaic potyvirus (ZYMV) antisera. Leaf extracts of ashgourd, cucumber and pumpkin reacted with antibodies against cucurbit aphid‐borne yellow luteovirus (CABW). No samples reacted with antiserum to watermelon mosaic‐2 potyvirus (WMV‐2) or squash mosaic potyvirus (SqMV). Some papaya and most cucurbits leaf samples cross‐reacted with antibodies against Moroccan (Mor) and Algerian (Alg) isolates of WMV. The Nepalese PRSV isolate was related to but distinct from a PRSV‐W type strain from France. This is the first report on the identity of ZYMV and CABW in Nepal.
The effect of soil freezing on the survial of winter‐sown white lupins (Lupinus albus L.)
Authors: LEACH J E , STEVENSON H J , ScOTT T. , MILFORD G F J
Published: February 2008

Specially constructed soil‐freezing growth boxes were used to study the effects of the intensity and duration of soil freezing on root injury and the survival of white lupin seedlings of different ages under controlled conditions. The extent of root damage depended on both the intensity of soil freezing and the stage of seedling development (measured as the extent of lignification of the central stele of the primary root). Seedlings whose secondary root development was well advanced, and in which the endodermis was completely lignified, survived intense soil freezing intact. Young seedlings with weakly lignified roots were damaged by moderate soil freezing (> 5 days at −1°C) and killed by more intense freezing (5 days at −2°C). The extent of root development and ligmfkation was correlated with the number of leaf primordia produced at the shoot apex so that the susceptibility to soil freezing damage could be accurately predicted by a simple physiological/leaf production model.
Virus‐like particules in the poison glant of the parasitic wasp Opius concolor
Authors: JACAS J A , BUDIA F. , RODRÍGUEZ‐CEREZO E. , VIÑUELA E.
Published: February 2008

Virus‐like particles (VLP's) have been found in the poison glands of adult females of the parasitic wasp Opius concolor Szèpl. (Hymenoptera, Braconidae). These VLP's are found in the secretory cells either free in the cytoplasm or within cytoplasmic vesicles, sometimes associated to a secretory apparatus.

Negative staining of these VLP's has revealed the occurrence of two different particles. The first type exhibits icosahedral symmetry (diameter around 70nm) and hollow surface spikes, this morphology being typical of the genus Cypovirus (Reoviridae). The other type is pleomorphic and presents an envelope with clubshaped projections (diameter ranging from 30 to 60nm), as classical textbook examples of Coronaviruses, but smaller. Function and full characterisation of these particles are not yet known.
Effects of azinphos‐methyl and pyrifenox on reproductive performance of Cydia pomonella L. (Lepidoptera: Tortricidae) at recommended rates and lower concentrations
Authors: ABIVARDI CYRUS , WEBER DONALD C. , DORN SILVIA
Published: February 2008

The effects of deposits of commercial formulations of azinphos‐methyl, an organophosphorous insecticide and acaricide, and pyrifenox, a systemic fungicide, on artificial surfaces on the survival and reproductive performance of codling moth adults, Cydia pomonella L., were examined in the laboratory. In contrast to pyrifenox, which did not influence the codling moth significantly, azinphos‐methyl affected the insect in a number of ways: (1) it exhibited a strong direct insecticidal activity on adults, eggs and larvae; (2) at low concentrations, it decreased copulation significantly, as reflected by a reduction in the number of spermatophores contained per female; and it inhibited oviposition strongly; (3) at low concentrations moths copulated more often initially and produced more eggs than the controls. However, if the moths were kept in contact with the azinphos‐methyl residues, they and their progeny died the following day so that the total number of eggs laid was reduced.

Possible implications of the stimulatory effects, as well as repellency, of combined use of azinphos‐methyl in the phermone mating disruption technique are discussed.
Splash dispersal of Coniothyrium minitans in the glasshouse
Authors: WILLIAMS R H , WHIPPS J M , COOKE R C
Published: February 2008

Coniothyrium minitans, a mycoparasite with biocontrol activity against Sclerotinia sclerotiorum, was found to disperse during glasshouse trials where overhead irrigation was used. Consequently, the role of water splash in dispersal of C. minitans was investigated using soil‐incorporated inoculum and a range of irrigation regimes found to occur in the glasshouse. The resulting inoculum deposition over horizontal distances up to 2 m was measured. Using drops < 6 mm diameter at 680 mm h‐1, C. minitans was splash‐dispersed at least 2.0 m, whereas with drops > 6 mm diameter at 30 mm h‐1 it was dispersed to only 1.75 m. Irrigation with droplets < 1mm diameter at 49 mm h‐1 failed to disperse inoculum beyond 0.5 m. The dispersal gradient produced by drops < 6 mm diameter at 680 mm h‐1 was best described mathematically by the power function, whereas irrigation with drops > 6 mm diameter at 30 mm h‐ resulted in a gradient described well by power or exponential functions. The latter regime produced a significantly steeper gradient than irrigation with drops < 6 mm diameter at 680 mm h‐1. C. minitans was isolated using an Andersen air sampler at concentrations of 2839 cfu m‐3 or 22 cfu m‐3 during irrigation with drops < 6 mm diameter at 680 mm h‐1 or > 6 mm diameter at 30 mm h‐1, respectively. After irrigation, deposition of C. minitans‐canying aerosol particles declined exponentially and distance from source had no effect on the amount of inoculum isolated. Conidia of C. minitans, splash‐dispersed by irrigation with drops < 6 mm diameter at 680 mm h‐1 were able to infect sclerotia of S. sclerotiorum such that almost all sclerotia at 0.5 m from the inoculum source, and c. 50% of those at 2.0 m, became infected with the mycoparasite.
Durian flowering, pollination and incompatibility studies
Authors: LIM T K , LUDERS L.
Published: February 2008

Seasonal fluctuations in weather conditions were found to influence the flowering and fruiting phenology and reproductive biology of durian grown around Darwin. Manually assisted cross‐pollination resulted in higher fruit set of 31% in contrast to < 10% by selfing, producing higher yields and better quality fruit. Self‐pollination resulted in more fruit abortion and produced fruits that were mis‐shapen, curved with lower numbers of arils/locule, arils/fruit and lower numbers of seeds which were usually shrunken and disfunctional. Evidence from these studies also confirmed that the self‐incompatibility system in durian is gametophytically controlled and that cultivars could be totally self‐incompatible, partially self‐incompatible or totally compatible. The durian pollen was found to exert metaxenia effects that influenced the development of the fruit characteristics and also xenia effect on the seed.
Seedling and adult plant peaetions of Brassica napus‐B. juncea recombinant lines towards A‐ and B‐group isolates of Leptosphaeria maculans
Authors: SOMDA I. , RENARD M. , BRUN H.
Published: February 2008

The Brassica napus‐B. juncea recombinant lines MX and MXS carrying a B. juncea major gene (JLml) in the genetic background of a spring‐ or a winter type B. napus cultivar, respectively, were tested for their resistance level to Leptosphaeria maculans under controlled conditions. Inoculation with three A‐and four B‐group individual isolates and with different mixtures of isolates realised within or between these groups was performed on cotyledons, leaves and stems. Cotyledons and leaves of the two recombinant lines were more resistant to A‐group isolates than those of B. napus cultivars, except for one isolate recovered from the MX line. The recombinant lines were susceptible at cotyledon stage and resistant on leaves to B‐group isolates, as were B. napus cultivars. On stems, severe cortical damage was usually produced on B. napus cultivars by some A‐group isolates, whereas B‐group isolates induced pith blackening on all genotypes. Stems of the MX line and the resistant donor species (B. juncea cv. Picra) were more resistant than those of the susceptible B. napus (cv. Westar) to the individual A‐group isolates. Cultivar Picra was the most susceptible genotype to pith infection caused by the B‐group isolates. The consequence of the host pathogen differential interactions on the durability of the monogenic resistance to L. maculans introduced from B. juncea into B. napus is discussed.
A new group of endophytes in European grasses
Authors: NAFFAA W. , RAVEL C. , GUILLAUMIN J J
Published: February 2008

Poaceae of subfamily Festucoideae frequently harbour endophytic, symbiotic fungi in their aerial parts. Isolations were made from 21 different species of Poaceae, belonging mainly to the genera Lolium and Festuca. Pure cultures of 45 fungal isolates were obtained. Morphology, isozyme and molecular analysis showed the presence of three groups of endophytes. Most of the isolates could be accommodated with the previously described species of Neotyphodium and Epichloë (the e endophytes). Two new endophytes isolated from Koeleria cristata and Melica ciliata were shown to belong to this group. Gliocladium like and Phialophora like isolates were obtained from Lolium perenne and Festuca gigantea respectively (the p endophytes). Nine isolates especially those from annual Lolium produced rod like conidia. These isolates belong to Acremonium sensu stricto and are morphologically similar to Acremonium chilense.
Disease development of Pythium root rot in bulbous Iris and Crocus
Authors: OS G J VAN , GULIK W J M VAN , BOER W J DE
Published: February 2008

Iris bulbs and Crocus corms were planted at two planting dates in sandy soil infested with Pythium spp. At monthly intervals during the growing season root rot infection was assessed over 3 consecutive years and disease development curves were predicted for both crops. The disease development was remarkably different for Iris and Crocus and the curve shape was determined by the crop rather than by the Pythium species. Planting date had a significant effect on disease development in both crops. No correlation was found between disease development and soil temperature.
Effect of nitrogen on interactions between ryegrass mosaic virus (RMV) and Lolium species in mixed swards
Authors: BAIN R A , RAYNOR E L , BAKER L J , BAGNALL A.
Published: February 2008

The effect of rate of nitrogen applied to three Lolium perenne‐based field swards on the development of RMV symptoms and on the impact of the virus on the growth and composition of the swards was examined over two growing seasons. Glasshouse experiments investigated the competition between Lolium spp. in relation to RMV infection and rate of nitrogen. In general, there was a higher incidence of RMV symptoms at the higher rates of nitrogen but the relationship was not consistent in all experiments. RMV infection only significantly reduced the cumulative total yield of the sward that contained the very susceptible Lolium multiflorum cv. Barverdi and was treated with the higher rate of nitrogen. However, yield losses were consistently greater at the higher rates of nitrogen. RMV altered the relative yields of sward components and the effect was greatest after an extended period of severe frost at the end of 1995. There is evidence that the frost severely restricted the yield of RMV‐infected L. multiflorum tillers in 1996. Where RMV reduced the yield of susceptible species, there was significant compensatory growth by less susceptible companion species, i.e. L. perenne and Phleum pratense, but the compensation was generally incomplete, resulting in reduced yields for virus‐infected swards. RMV had no significant effect on the overall quality of the three field swards but for cv. Barverdi grown in the glasshouse it significantly reduced the percentage organic matter and water soluble carbohydrate, and D value. The reductions were greater at the higher rates of nitrogen.
Aspects of resistance to sweet potato virus disease in sweet potato
Authors: ARITUA V. , ALICAI T. , ADIPALA E. , CAREY E E , GIBSON R W
Published: February 2008

In field trials during the first and the second rainy season of 1996 in Uganda, whiteflies were similarly abundant and aphids were absent on three clones of sweet potato (NIS‐93–63, cv. Tanzania and cv. New Kawogo) although the three clones differed considerably in their resistance to sweet potato virus disease (SPVD), a complex disease resulting from infection by both the aphid‐borne sweet potato feathery mottle virus (SPFMV) and the whitefly‐borne sweet potato chlorotic stunt virus (SPCSV). This suggests that vector resistance does not determine the relative SPVD resistance of these genotypes. SPFMV alone had only a low virus titre in sweet potato cvs Tanzania and New Kawogo, became increasingly difficult to detect in plants of these cultivars and was seldom acquired by aphids. However, this resistance to SPFMV was not apparent in plants which were also infected with SPCSV. Plants then had a high SPFMV titre, appeared unable to eliminate SPFMV and provided good sources for aphids to acquire it.
Detection of hatching inhibitors and hatching factor stimulants for golden potato cyst nematode, Globodera rostochiensis, in potato root leachate
Authors: BYRNE J. , TWOMEY U. , MAHER N. , DEVINE K J , JONES P W
Published: February 2008

In a comparison of four potato varieties, in‐soil hatch of the golden potato cyst nematode (Globodera rostochiensis) was positively correlated to in vitro hatch in response to potato root leachate (PRL). The in‐soil hatch of cysts of G. rostochiensis to two of the four varieties was significantly less than that of the control (cysts in gravel without potato plants) in the first 2 wk after plant emergence, suggesting the production of hatching inhibitors (HIs) by young potato plants. The hatching factor: hatching inhibitor ratio of PRL was positively associated with the net hatching activity of the PRL. Four zones of HI activity were resolved following gel permeation chromatography of PRL on Sephadex G‐10. Hatch‐inactive chemicals, which stimulated the activity of hatching factors (HFs) in PRL (hatching factor stimulants, HSs), were also isolated from PRL, hatch levels induced by individual HFs responding differently to the same HS preparation. The complex interactions between individual HFs and other hatching chemicals in PRL was illustrated when addition of the hatch‐active potato glycoalkaloid α‐solanine caused both inhibition and stimulation of PRL‐induced hatch, depending on the α‐solanine concentration.
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

Rosette 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
The role of different slug species in damage to oilseed rape bordering on sown wildflower strips
Authors: FRANK T.
Published: February 2008

Damage caused by different slug species on above and below ground parts of young oilseed rape bordering on sown wildfower strips was studied. Slug densities and damage were recorded in the field and damage rates for each slug species were measured in the laboratory. Severe slug damage was observed in rape areas 1 m from the wildflower strips. Damage rates of slug species feeding above ground were distinctly higher than those feeding below ground. The estimated damage caused by above‐ground feeding in all four study fields ranged between 72% and 89 % and was always distinctly higher than damage caused by below‐ground feeding (11% to 28 %). The estimated damage caused by Arion lusitanicus above ground was between 54% and 69 %, followed by Deroceras reticulatum (3% to 26 %). Thus A. lusitanicus was responsible for the majority of damage in the rape crops studied.
Typing Primus necrotic ringspot virus isolates by serology and restriction endonuclease analysis of PCR products
Authors: SPIEGEL S. , TAM Y. , MASLENIN L. , KOLBER M. , NEMETH M. , ROSNER A.
Published: February 2008

Primus necrotic ringspot virus (PNRSV) isolates were characterised by bioassays, serotyping and restriction fragment length polymorphism (RFLP) analysis of PCR products. Based on symptoms in host trees and bioassays it was concluded that only one of the 16 tested isolates is severe. The serotyping results demonstrated that by using four different MAbs in TAS‐ELISA the tested isolates could be divided into four subgroups, however, the severe isolate could not be singled out. RFLP analysis of PCR products supported the serotyping data but did not differentiate between isolates of the two main serological subgroups. A restriction map, derived from sequence analysis of the PCR products obtained from selected isolates, allowed exact location of the restriction sites within the PCR products of each isolate. A mild isolate with a unique genome structure was identified by both serological and RFLP assays. As far as we are aware, this is the first report on sub‐grouping of PNRSV isolates by bioassays, serotyping with MAbs and RFLP analysis.