bluuebunny/crossref_metadata_2025 huggingface dataset:
The efficiency of a new lightweight suction sampler for sampling aphids and their predators in arable land
Authors: MACLEOD A , WRATTEN S D , HARWOOD R W J
Published: February 2008

A petrol driven machine, normally used to collect leaf litter, was modified to be used as a suction sampler for polyphagous predators in cereals and grassy habitats and aphids in cereals. Recovery efficiency of Araneae, Carabidae and Staphylinidae did not differ significantly between winter sampling from Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus or Lolium perenne although the structure of these grasses was very different. Summer sampling of aphids and their predators in winter wheat showed that the new sampler captured significantly more target organisms per unit area than did a traditional suction sampler. The machine was also lighter, cheaper and much easier to use than a traditional machine.
Limited degree of serological variability in pepper strains of potato virus Y as revealed by analysis with monoclonal antibodies
Authors: SOTO M J , ARTEAGA M LUIS , FERERES A , PONZ F
Published: February 2008

The degree of serological variability among pepper strains of potato virus Y (PVY) was assessed through the analysis of samples of infected pepper collected in three main pepper producing regions of Spain. Samples corresponding to the period 1980–1991 were analysed by ELISA with five different monoclonal antibodies (MAbs) produced against potato strains of the virus. The results obtained show a limited degree of epitope variability among pepper PVY‐isolates, since only eight out of 32 possible serological profiles were found. Most isolates are not recognised by a MAb directed towards an epitope reported to be present in all potato‐PVY isolates. The overall serological behaviour of pepper isolates with these MAbs places them as closer to the group O, of the three groups into which the potato isolates of PVY have been subdivided.
Effect of mulching with cereal straw and row spacing on spread of bean yellow mosaic potyvirus into narrow‐leafed lupins (Lupinus angustifolius)
Authors: JONES R A C
Published: February 2008

Two field experiments examined the effect of straw spread on the soil surface on the incidence of bean yellow mosaic potyvirus (BYMV) in plots of narrow‐leafed lupin (Lupinus angustifolius) sown at narrow (17.5 cm) vs wide (35 cm) row spacing and low (25–30 kg/ha) vs medium (50–60 kg/ha) seeding rates. Virus ingress was by vector aphids flying from adjacent pastures dominated by subterranean clover. In Expt 1, in which BYMV infection was extensive, straw greatly decreased the rate and amount of virus spread regardless of row spacing or plant density, decreasing infection more than 70% by the final assessment date. This effect of straw was attributed to decreased landing rates of incoming vector alates. In the plots without added straw, narrow row spacing decreased BYMV % infection by 38% by the last assessment date. Sowing at the medium seeding rate also decreased infection. The effect of wide row spacing seemed due to delayed canopy closure between rows which is likely to have increased the landing of aphids while the effect of medium seeding rate was attributed partly to the dilution effect of greater plant numbers and partly to the effects of partial canopy development in decreasing landing rates. In Expt 2, in which the incidence of BYMV infection was low, added straw again decreased BYMV spread, but by only 25–27% at final assessment; there were no effects of row spacing or seeding rate. In both experiments, an additional “reference” treatment was included which had a high (90–100 kg/ha) seeding rate, narrow rows and no straw. The dense canopy it developed also decreased BYMV incidence but less than in the plots with added straw in Expt 1.

In Expt 1, adding straw and the resulting decrease in plants killed by BYMV, were associated with an overall increase in lupin grain yield of 20%. The greater plant densities resulting from the medium seeding rate also increased grain yield but row spacing did not affect it significantly.

These results indicate that retaining stubble on the soil surface at seeding will assist in management of BYMV infection in lupin crops but that wide row spacing in the absence of retained stubble is undesirable.
Comparative host tissue Réactions of Musa acuminate (AAA group) cvs Poyo and Gros Michel roots to three banana‐parasitic nématodes
Authors: MATEILLE THIERRY
Published: February 2008

In a comparative histopathological investigation, Poyo and Gros Michel cul‐tivars of Musa acuminata (AAA triploid) were inoculated with Radopholus similis, Helicotylenchus multicinctus or Hoplolaimus pararobustus and were grown in a greenhouse under tropical conditions. R. similis infected all the cortical parenchyma layers of the roots, reaching the vascular cylinder, but it stayed more superficial in Gros Michel roots. Red‐brown cytoplasmic globules appeared in the cortical parenchyma cells of Gros Michel only. H. multicinctus infected much of the outer cortical parenchyma in roots of both cultivars with a few phenolic cells occurring around the superficial lesions. H. pararobustus penetrated only the immediate sub‐epidermal tissues in both cultivars. The differences observed between nématodes and cultivars reflect specific host‐nematode interactions on bananas.
Effects of nitrogen fertiliser on tree/ pasture competition during the establishment phase of a silvopastoral system
Authors: CAMPBELL C D , ATKINSON D , VIS P G JAR , NEWBOULD P
Published: February 2008

The establishment phase of an upland silvopastoral system was studied to examine the growth and nutrition of wild cherry (Prunus avium L.) trees under different nitrogen fertiliser treatments. High rates of nitrogen fertiliser exacerbated competition between trees and pasture in a dry year when low fertiliser treatments produced faster tree height growth. When herbicides were not used to control grass growth after the third growing season, tree growth was significantly reduced showing that below‐ground competition may be a significant factor on stony upland soils. Tree growth was correlated with foliar nitrogen concentrations and not soil water, suggesting competition for soil nitrogen reduced tree growth. The importance of the interaction of fertiliser use with competition is considered in relation to successful establishment.
Salt tolerance of pigeon pea (Cajanus cajan (L.) Millsp.) at three growth stages
Authors: ASHRAF M
Published: February 2008

Salt tolerance of pigeon pea (Cajanus cajan (L.) Millsp.) was determined at three growth stages following observations by a number of workers that degree of salt tolerance of different crops varies with their ontogeny. The salt tolerance of three accessions, Local arhar, ICPL‐151 and ICPL‐850014 of pigeon pea was assessed at the germination, seedling and adult stages.

There was no positive correlation between tolerance at the early growth stages and at the adult stage since no clear difference in salt tolerance of the three accessions was observed at the germination and the seedling stages, whereas accessions differed considerably at the adult stage.

Although increasing salt concentrations adversely affected the growth of all three accessions, ICPL‐151 was superior to the other two accessions in fresh and dry biomass, yield and yield components when tested at the adult stage. The tolerant accession, ICPL 151, accumulated significantly lower Na+and CI in shoots. By contrast it was higher in shoot and root K+, K/Na ratios, K vs Na selectivity, soluble sugars, free amino acids and proline compared with the other two accessions.
Distribution and prevalence of the predatory planarian Artioposthia triangulata (Dendy) (Trieladida: Terricola) in Scotland
Authors: BOAG B , PALMER L F , NEILSON R , CHAMBERS S J
Published: February 2008

The distribution of the New Zealand flatworm (Artioposthia triangulata) in Scotland was surveyed between July 1991 and February 1993. There were 348 records from domestic gardens, 56 from botanic gardens, garden centres and nurseries, with only 13 from farms. Although most of the records came from around the major cities the flatworm was found to have become established throughout the Scottish mainland and some of the Islands, e.g. Bute, Gigha, Orkney and Skye.

The impact of the flatworm on earthworm populations in agricultural land in Scotland was, as yet, found to be minimal but the fact that seven adjacent farms near Dunoon were infected suggested it could be spread from farm to farm and that in the West of Scotland it could become widespread in agricultural land.
Effects of previous cropping and fungicide timing on the development of light leaf spot (Pyrenopeziza brassicae), seed yield and quality of winter oilseed rape (Brassica napus)
Authors: FIGUEROA L , SHAW M W , FITT B D L , McCARTNEY H A , WELHAM S J
Published: February 2008

Light leaf spot, caused by Pyrenopeziza brassicae, was assessed regularly on double‐low cultivars of winter oilseed rape during field experiments at Rothamsted in 1990‐91 and 1991‐92. Previous cropping and fungicide applications differed; seed yield and seed quality were measured at harvest. In each season, both the initial incidence of light leaf spot and the rate of disease increase were greater in oilseed rape crops sown after rape than those sown after cereals. The incidence of diseases caused by Phoma lingam or Alternaria spp. was also greater in second oilseed rape crops. In 1991‐92 there was 42% less rainfall between September and March than in 1990‐91, and much less light leaf spot developed. However, P. lingam and Alternaria spp. were more common. Only fungicide application schedules including an autumn spray decreased the incidence of light leaf spot on leaves, stems and pods, as indicated by decreased areas under the disease progress curves (AUDPC) and slower rates of disease increase. Summer sprays decreased incidence and severity of light leaf spot on pods only. In 1990‐91, all fungicide treatments which included an autumn spray increased seed and oil yields of cv. Capricorn but only the treatment which included autumn, spring and summer sprays increased yields of cv. Falcon. No treatment increased the yields of cv. Capricorn or cv. Falcon in 1991‐92. Fungicide applications decreased glucosinolate concentrations in the seed from a crop of cv. Cobra severely infected by P. brassicae in 1990‐91, but did not increase yield.
Properties of an unusual isolate of raspberry ringspot virus from grapevine in Germany and evidence for its possible transmission by Paralongidorus maximus
Authors: JONES A T , BROWN D J F , McGAVIN WENDY J , RÜDEL MARIA , ALTMAYER B
Published: February 2008

An isolate of raspberry ringspot nepovirus (RRV‐P) commonly found infecting grapevine in localised areas of the German Palatinate, was serologically closely related to, but distinguishable from, the English type strain of this virus (RRV‐E) which is transmitted by Longidorus macrosoma. However, unlike RRV‐E, RRV‐P had a restricted herbaceous host range and produced symptoms reliably in only two hosts, Chenopodium quinoa and Nicotiana occidentalis‐accession 37B: these symptoms were a faint systemic vein clearing which, on most occasions in C. quinoa, was transient. In in vitro studies with herbaceous plant sap, RRV‐P infectivity was lost after diluting 1/100 ‐1/500, after storage at 20oC for 1–3 days and at 4oC for 45 days: for similar studies with RRV‐E, the values were 1/125 000, and more than 15 days at 20oC and 4oC, respectively. RRV‐P was difficult to purify in quantity and in most preparations seemed to sediment as a single component corresponding to ‘bottom’ component of RRV‐E. Purified particles of RRV‐P, like those of RRV‐E, contained a major polypeptide and two RNA species of Mr 54 000, 2.6 times 106and 1.6 times 106respectively. There was no evidence from RNA preparations from purified virus particles or, from analysis of dsRNA from infected plants, that RRV‐P contained a satellite RNA. The incidence of RRV‐P in vineyards was not associated with the presence in soils of Longidorus nematodes, but was associated with the distribution in the Palatinate of Paralongidorus maximus. Furthermore, results from an experiment in Germany in a vineyard planted with healthy grapevines in soil fumigated to destroy nematodes, showed spread of RRV‐P into these plants from an adjoining source of infected grapevines and soil infested with P. maximus. In laboratory studies, RRV‐P was transmitted by P. maximus at a very low level between grapevines (used as the virus source and test plants) but not to, or between, herbaceous hosts.
Transfer of resistance to potato leafroll virus, potato virus Y and potato virus X from Solarium brevidens to S. tuberosum through symmetric and designed asymmetric somatic hybridisation
Authors: VALKONEN J P T , XU Y‐S , PULLI S , PEHU E , ROKKA V‐M
Published: February 2008

Resistance to potato leafroll virus (PLRV), potato virus Y (PVYo) and potato virus X (PVX) was studied in symmetric and asymmetric somatic hybrids produced by electrofusion between Solanum brevidens (2n=2×=24) and dihaploid S. tuberosum (2n=2×=24), and also in regenerants (B‐hybrids) derived through protoplast culture from a single somatic hybrid (chromosome number 48). All of the somatic hybrids between 5. brevidens and the two dihaploid lines of potato cv. Pito were extremely resistant to PLRV and PVYoand moderately resistant to PVX, irrespective of their chromosome number and ploidy level (tetraploid or hexaploid). Most (56%) of the asymmetric hybrids of irradiated S. brevidens and the dihaploid line of potato cv. Pentland Crown (PDH40) had high titres of PVYosimilar to those of PDH40, whereas the rest of the hybrids had PVYotitres less than a tenth of those in PDH40. Three B‐hybrids had a highly reduced chromosome number (27, 30 and 34), but were however as resistant to PLRV, PVYoand PVX as 5. brevidens. Two asymmetric hybrids and one B‐hybrid were extremely resistant to PLRV but susceptible to both PVY and PVX. The results suggested that resistance to PLRV in 5. brevidens is controlled by a gene or genes different from those controlling resistance to PVY and PVX, and the gene(s) for resistance to PVY and PVX are linked in S. brevidens.
Seasonal growth of tree lupins (Lupinus arboreus) and the effect of defoliation on leaf production
Authors: MARRIOTT CAROL A , SMITH MORAG A
Published: February 2008

The growth of tree lupins was investigated in two experiments. In the first, two ages of plant, 4‐wk‐old seedlings and 1‐year‐old plants, were transplanted into a ryegrass sward in an upland environment. Growth, in terms of leaf production, branching and stem elongation, was measured over two successive growing seasons. Plant dry matter and nutrient contents were determined at the beginning and end of each growing season. In the first summer, the rate of production of new leaves on the main stem of seedling plants averaged 1.8 leaves per wk and main stem length increased from 5 to 67 cm. On older plants, where floral apices had been initiated on main and primary stems, there was a 3–10 fold increase in secondary branch length. In the second season, there was no effect of plant age on rates of leaf appearance or stem extension; dry matter production was higher than in the first season.

In the second experiment, the effect of removal of 0%, 50% or 100% of fully expanded leaves on the subsequent growth of 23‐wk‐old plants was investigated. During the 7‐wk growth period, defoliation promoted the rate of production of mature leaves, and area and dry weight of new laminae were slightly higher in defoliated plants. Defoliation did not affect the concentrations of N, P or K in the new laminae, but P and K concentrations in petioles of defoliated plants were significantly higher than those in intact plants.

The results from the experiments are discussed in relation to the potential use of tree lupins as nurse species and biomass crops in hill and upland environments of the UK.
PCR detection of MLOs in quick decline‐affected pear trees in Italy
Authors: GIUNCHEDI L , POLLINI C POGGI , BIONDI S , BABINI ANNA ROSA
Published: February 2008

Polymerase chain reaction (PCR) amplification, using primers derived from the 16S rRNA gene, followed by restriction fragment length polymorphism (RFLP) analysis with Alu I restriction endonuclease was used to detect myc‐oplasma‐like organisms (MLOs) associated with pear decline. MLOs were consistently detected in pear trees that suddenly wilted and died within a few days during summer, as well as in pears of the same orchards with symptoms similar to the slow form of pear decline. In both cases the same RFLP pattern was obtained. Declining pear trees were 5 to 8‐yr‐old cvs Williams, Kaiser and Max Red Bartlett grafted on to Pyrus communis seedling rootstocks. All the orchards affected by quick decline had severe attacks of pear psyllid (Cacopsylla pyri) during the year this study was performed and during the previous year. The results showed the suitability of DNA amplification by the polymerase chain reaction for the detection of pear decline MLOs and established that MLOs can be detected in infected tissues of dead trees.
Virus‐vector relationships of chickpea chlorotic dwarf geminivirus and the leafhopper Orosius orientalis (Hemiptera: Cicadellidae)
Authors: HORN N M , REDDY S V , REDDY D V R
Published: February 2008

Chickpea chlorotic dwarf geminivirus (CCDV) is one of the viruses associated with chickpea stunt disease. It is transmitted by the leafhopper Orosius orientalis. The minimum acquisition access period (AAPmin) and inoculation access period (IAPmin) were found to be less than 2 min, while the minimum latency period (LPmin) was less than 2 h. The median AAP, IAP and LP were 8.0 h, 2.3 h and 27.7 h, respectively. No difference in transmission rates (proportion of leafhoppers able to transmit) was observed between male and female leafhop‐pers. In serial transmission experiments, transmission was shown to be persistent, and after a 2‐day AAP about 80% of the leafhoppers transmitted the virus for most of their life. The virus could be detected in individual leafhoppers by DAS‐ELISA. It did not multiply in the leafhopper, but, instead, decreased in concentration during leafhopper feeding on a non‐host of the virus.
Multiplication of English isolates of potato pale cyst‐ nematode, Globodera pallida, on potatoes of differing nematode resistance and the identity of potato cyst‐ nematode populations
Authors: WHITEHEAD A G , RUSSELL M D
Published: February 2008

In pots, 25 populations of potato pale cyst‐nematode, Globodera pallida Stone, differed significantly in their ability to multiply on potato clones P55/7 and ZC83/ 6, both fully resistant to G. pallida pathotype Pal. Neither clone was fully resistant to any of the populations. For 21 populations common to this and an earlier experiment, increase on the more resistant potatoes (P55/7, ZC83/6, cvs Sante, Paladin and Glenna) was correlated with their increase on less resistant potatoes (cvs Morag, Fingal and Valiant). Variation in virulence on these partially resistant potatoes was not matched by differences in the electrophoretic patterns of the nematodes' proteins. The identification of populations of G. rostochiensis (Woll.) Skarbilovich used in these experiments was confirmed by electrophoresis. All populations of G. pallida Stone, appeared to contain very small numbers of G. rostochiensis after subculture on susceptible potatoes (cv. Désirée).
The persistence and spread of Xiphinema diversicaudatum in cultivated and uncultivated biotopes
Authors: TAYLOR C E , BROWN D J F , NEILSON R , JONES A T
Published: February 2008

The distribution of Xiphinema diversicaudatum in an uncultivated woodland habitat in England and a cultivated soil in Scotland, was re‐investigated in 1991 after an interval of 30 and 24 years, respectively. In the undisturbed habitat, nematodes had a distribution similar to that in 1961 but with a lower population density. In the cultivated habitat, nematodes were aggregated in several discrete populations associated with the cultivation and change of cropping in the intervening years but had spread little further horizontally into the raspberry crop, planted in 1982. Although strawberry latent ringspot and arabis mosaic nepoviruses were present in 1966, only the latter virus was found in crop and weed plants in 1991.

The X. diversicaudatum populations from the two locations were morphologically similar to each other and to other populations, including those used for a redescription of the species.
Induction of resistance mechanisms in barley by yeast‐derived elicitors
Authors: REGLINSKI T , LYON G D , NEWTON A C
Published: February 2008

Yeast cell‐wall extracts (YE) had high phytoalexin elicitor activity on soybeans and induced resistance against barley powdery mildew in the normally highly susceptible cv. Golden Promise. Following treatment with YE there was rapid stimulation of phenylalanine ammonia‐lyase (PAL) activity and faster formation of papillae in response to attempted fungal penetration. The spray adjuvants Agral and LI‐700 each had poor phytoalexin elicitor activity and caused a slight enhancement of papilla formation and a low level of mildew control. The addition of the adjuvant to YE did not affect phytoalexin elicitation on soybeans but significantly enhanced the speed and the extent of PAL activity, papilla formation and mildew control. It is proposed that this is due to greater coverage and improved persistence enabling increased uptake of YE into the barley leaves.
Morph identification in natural populations of alate female bird cherry aphids, Rhopalosiphum padi L., by multivariate methods
Authors: TAYLOR M S , TATCHELL G M , CLARK S J
Published: February 2008

A discriminant analysis was done to determine which morphological characteristics contributed most to the identification of alate female morphs of Rhopalosiphum padi in natural populations collected from either Prunus padus or in suction traps. Twenty two characters were measured or counted, including wing dimensions, and three ratios were included. Analyses were done to separate morphs that might occur naturally together, i.e. emigrants and ‘early’ exules, or ‘late’ exules and gynoparae. Emigrants were distinguished readily from early exules, but gynoparae were not so easily separated from late exules. The biological significance of the morphological differences between morphs and the practical implications of being able to identify the different morphs are discussed.
Effects of water stress, nitrogen stress and certain sensory stimuli on infestation and damage by Chilo partellus (Swinhoe) to maize
Authors: KUMAR HARISH
Published: February 2008

Foliar, stalk and dead heart damage caused by Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) to several maize genotypes (Inbred A, MBR 8637, Poza Rica 7832, ER‐29SVR, Across 7844, Bulk CG 4141, MMV 600 and ICZ2‐CM) subjected to water stress were significantly lower than those observed when plants were grown in the absence of water stress. Resistance of maize genotypes to C. partellus was distinguished clearly when there was no water stress to the plants. Resistance/susceptibility of maize genotypes Inbred A, MMV 400, MBR 8637 and Poza Rica 7832 to C. partellus was the same at 0, 60, 90 and 120 kg of N per hectare. At each nitrogen level, the genotypes MMV 400, MBR 8637 and Poza Rica 7832 suffered significantly lower damage than the susceptible Inbred A. The humidity stimuli from maize plants and the olfactory/hygro stimuli from the plants infested with larvae were the most important factors affecting host plant selection by ovipositing C. partellus females.
Genetic variation in resistance toFusarium oxysporumf.sp.liliiin the genusLilium
Authors: STRAATHOF Th P , van TUYL J M
Published: February 2008

Genetic variation inFusariumresistance in 82Liliumgenotypes was studied. A high level of resistance was found in the Asiatic hybrids (sectionSinomartagon) and to a lesser extent in cultivars ofL. longiflorum(sectionLeucolirion). The Oriental hybrids (sectionArchelirion) showed only moderate resistance. In the sectionsSinomartagon, LeucolirionandMartagonspecies were detected with high levels of resistance. An accession ofL. dauricum(sectionSinomartagon) was the most resistant source. Possibilities for introgression ofFusariumresistance into cultivars by interspecific hybridisation, using the resistance found inLiliumgenotypes, are discussed.
In vitro spore germination and infection of cultivars of Rubus and Rosa by downy mildews from both hosts
Authors: BREESE WENDY A , SHATTOCK R C , WILLIAMSON B , HACKETT CHRISTINE
Published: February 2008

The cardinal temperatures for in vitro germination of conidia of imported and indigenous isolates of downy mildew from hosts in the genera Rubus and Rosa were similar. A high percentage of conidia germinated above 2°C and germination remained between 80% and 90% up to 15°C or 20°C, depending on the isolate. The highest incidence of disease on leaf disks of Tummelberry (blackberry × red raspberry) inoculated with an isolate of Peronospora rubi occurred at c. 15°C, with infection over a range from 2°C to 28°C. Tests on leaf disks in vitro, and leaflets of primocane and lateral shoots in plastic tunnels, with three hybrid berry (blackberry x red raspberry), six blackberry and nine red raspberry cultivars showed the hybrid berries to be most susceptible. In a plastic tunnel infected drupelets of red raspberry fruits developed more slowly and failed to ripen evenly compared with uninfected drupelets. Similar malformation of infected fruits occurred in a plantation of Tummelberry. An isolate of P. rubi attacked severely both Tummelberry and rose cv. Can Can. Fluorescence microscopy after staining with aniline blue showed that leaf disks of Tummelberry were extensively colonised by intercellular mycelium of P. sparsa isolated from rose, even though sporulation was sparse or absent. This supports the view that P. rubi and P. sparsa may be conspecific. Oospores of P. rubi were found routinely within leaf disks of Rubus cultivars inoculated in vitro and once in naturally infected leaflets of Tummelberry.
Genotypic influence on in vitro induction, dormancy length, advancing age and agronomical performance of potato microtubers (Solanum tuberosum L.)
Authors: RANALLI P , BIZARRI M , BORGHI L , MARI M
Published: February 2008

Microtubers of 13 cultivars, largely grown in Italy and other European countries, were induced. They were stored in the dark at 3°C for different periods (28, 56, 84 and 105 days), prior to being transferred to 20°C for between 4 and 17 weeks. Following removal to room temperature, sprouting was recorded and dormancy duration quantified. Dormancy decreased from 28.1 to 19.9, 11.1 and 7.8 days with reduced time of storage. Cvs Arsy, Nicola and Jaerla took consistently more time for dormancy release. The dormancy duration was linearly and inversely correlated with the length of storage. After sprouting, tubers were held at 20°C for various intervals and a range of physiological ages (0, 368, 720 and 1008 degree days) were accumulated. The field comparison of microtubers evidenced a plant growth response and tuber yield/plant affected by the cultivar and physiological age. In early cultivars (Jaerla), a better performance was shown by younger tubers; the opposite trend was noted in Alpha (a later cultivar) with an increase in stems/plant, tubers/plant and tuber yield/plant for tubers with greater physiological age. Like conventional seed tubers, microtubers showed differences in optimum physiological age associated with cultivar earliness. This study has provided some indications on how to enhance emergence and haulm development of plants from microtubers.
Genistein as an endogenous natural substrate of acidic peroxidases in lupin hypocotyls
Authors: FERRER M ANGELES , BARCELÓ A ROS
Published: February 2008

The localisation of peroxidase in the outermost cell layers of lupin (Lupinus albus L. cv. Multolupa) hypocotyls shows that peroxidase activity is present mainly in the epidermal cell layer in a similar way to isoflavones. The soluble peroxidase activity is due mainly to the presence of two peroxidase isoenzyme groups, one of an acidic nature (A1 and A2) and the other basic (B1 and B2). These isoenzymes, although present in epidermal tissues, are not tissue‐specific since they are also located in the soluble peroxidase fraction obtained from vascular tissues. These observations, and the fact that acidic peroxidases but not basic peroxidases are extremely active in the oxidation of genistein, a constitutive isoflavone of lupin hypocotyls, point to a role for acidic peroxidases in isoflavone turnover and degradation. Thus, manipulating peroxidase activity and/or its level would allow endogenous isoflavone levels to be controlled in order to grow lupins as a commercial fodder crop.
Interaction of bean leaf pubescence with rust urediniospore deposition and subsequent infection density
Authors: MMBAGA M T , STEADMAN J R , ROBERTS J J
Published: February 2008

The role of dense straight trichomes on bean leaves associated with race‐nonspecific resistance to rust was studied using a settling tower method for uniform inoculation. Abaxial leaf trichomes, which occur only on adult leaves, trapped significant numbers of urediniospores, especially those deposited in clusters, and resulted in reduced effective inoculum reaching the leaf surface. In the field where infection conditions are often less than optimum, leaf pubescence would partially explain the observed resistance. However, the observed increase in total number of spores as well as similar infection densities on fully expanded leaves of glabrous and pubescent genotypes cannot be explained by the trichomes. Other physical or chemical features of the leaf surface such as waxes or cations may play a role. The ecological fit of leaf pubescence is discussed.
Variation in cardinal temperatures for germination among wheat (Triticum aestivum) genotypes
Authors: ALI Z I , MAHALAKSHMI V , SINGH M , ORTIZ‐FERRARA G , PEACOCK J M
Published: February 2008

In most tropical regions where wheat is grown under irrigation, high temperatures at sowing adversely affect crop establishment and subsequent seedling survival. The objective of this study was to compare wheat (Triticum aestivum) genotypes for their ability to germinate and grow at high temperatures during the seedling stage. Twenty‐five seeds each of 14 spring wheat cultivars were placed on moist filter paper at different temperatures (5°C to 40°C) in a one‐way thermogradient plate to determine the cardinal temperatures for germination. Rate of germination at each temperature for each genotype was computed as the inverse of time taken for 50% of the seeds to germinate. Rate of germination for each genotype at different temperatures was modelled with temperature to determine the base (tb), and optimum (topt) temperatures. Response of germination to temperature for each genotype was calculated as the slope of a linear regression of the rate of germination on temperature below topt. Genotypes differed in their optimum temperatures and Mexipak (= Kalyansona) had the lowest. Range in base temperature among the genotypes was between 0°C and 2°C differences but were not statistically significant though they might be biologically significant. Genotypes differed in their response to temperature with Gomam having the lowest rate, implying that it was slow to respond to increasing temperatures. Debeira and Cham 6 showed a similar response. Three lines which had performed well in spring wheat evaluation trials for moderate rainfall areas under heat stress had the highest response rate.

It is concluded that combining higher optimum temperatures with faster response rates would result in better‐adapted germplasm for regions where high temperatures persist at sowing.
Ultrastructure of the black currant gall mite, Cecidophyopsis ribis (Acari: Eriophyidae), the vector of the agent of reversion disease
Authors: ROBERTS I M , JONES A T , AMRINE J W
Published: February 2008

Electron microscopy of ultrathin serial sections was used to determine the structure and anatomy of the eriophyid gall mite, Cecidophyopsis ribis, the vector of the agent of black currant reversion disease. The composite picture derived from these studies has determined the location of the food canal, and major internal organs of the mite. Detailed ultrastructural studies on the anterior of suitably orientated mites has also provided detailed information on the geometry and complex structure of three sets of stylets in the feeding apparatus. No evidence was found of structures resembling virus‐like particles or of other described plant pathogens in the feeding apparatus and food canal of mites obtained from black currant plants affected with reversion disease. However, little or no food was apparently present in the food canal of most mites examined. This is the first detailed report of the anatomy and the ultrastructure of the mouthparts of this important plant pest and vector.
Morphological factors of the central whorl leaf associated with leaf surface wetness and resistance in sorghum to shoot fly, Atherigona soccata*
Authors: SREE P S , NWANZE K F , BUTLER D R , REDDY D D R , REDDY Y V R
Published: February 2008

Earlier studies showed that leaf surface water on the central whorl leaf of sorghum seedlings is associated with resistance to shoot fly. In this study, the results of an experiment to determine if leaf surface wetness (LSW) originates from atmospheric condensation or from the plant are described. Morphological structures: trichomes, stomata, leaf cuticle and quantity of surface wax of the central whorl leaf were also examined for their role in LSW production. The results suggest that LSW of the central whorl leaf originates from the plant and is not due to condensation of atmospheric moisture. The presence of trichomes was indirectly associated with LSW and resistance to shoot fly but stomatal density was not associated with LSW production. The amount of wax extracted per 100 mg of fresh weight varied significantly between genotypes and seedling age. It was more in susceptible than in resistant genotypes; however, cuticular thickness was not associated with resistance. It is suggested that LSW could be the result of some form of cuticular movement of water to the leaf surface.
Seasonal development of apothecia of the cereal eyespot pathogen Tapesia yallundae on straw stubble in the UK
Authors: DYER P S , BATEMAN G L , LUCAS J A , PEBERDY J F
Published: February 2008

Five field sites growing winter wheat were inoculated with isolates of the W‐and R‐types of Tapesia yallundae in 1990 and 1991. After harvest, plots of uncultivated stubble were monitored for the production of apothecia during 1992 and 1993. Apothecia were found on the stem bases of straw stubble over a 9‐month period from mid‐October to July, but with a peak in numbers present during late January to March, 5 to 7 months after harvest. This was associated with mean monthly temperatures between 3°C and 8°C. Rainfall appeared to be less important than temperature in apothecial development. Single ascospore isolates obtained from apothecia collected from areas inoculated with W‐, R‐, or mixed W‐ and R‐type isolates all produced colonies with morphologies and growth rates characteristic of the W‐type. Thus there was no indication that the W‐ and R‐types are sexually compatible.
Thermal time and ecological strategies ‐ a unifying hypothesis
Authors: TRUDGILL D L , PERRY J N
Published: February 2008

Rates of embryogenesis and of development and growth in several nematodes are linearly related to temperature over a considerable range. On this basis, published data on the thermal time requirements are compared for a tropical and a temperate species of plant parasitic nematode Meloidogyne javanica and M. hapla respectively, the two being closely related and morphologically and biologically similar. M. hapla has a lower base temperature (Tb) and a higher thermal constant (S) than M. javanica with the relative values being almost inversed. Consequently, above their respective Tb values the slope of the relationship between rate of development and temperature was greater for the tropical species than that for the temperate species. A mathematical exploration of the relationship between Tb and S was made assuming that, over a narrow range, Tb×S was a constant. With this assumption, for any given average environmental temperature (Te) the optimum base temperature for minimum developmental duration was Te/2, and the temperature at which the duration of development was equal for the otherwise identical species was shown to be the sum of their base temperatures. The practical effect of the differences in Tb and S was to give M. hapla, the temperate species, a shorter life cycle and hence a competitive advantage at temperatures below 21ÅC and M. javanica, the tropical species, the advantage above that temperature. It is argued that a negative correlation between Tb and S is likely to be widespread, and provides a mechanism for regulating the distributions of related, competing organisms. Support for the hypothesis that the value of S tends to decrease as Tb increases is derived from data on the embryogenesis of an animal parasitic nematode Haemonchus contortus and from seed germination studies. Contrary results and exceptions are also briefly discussed. The observed interaction between Tb and S may be fundamental to many poikilothermic organisms and plants and provides an explanation for tropical species generally having higher Tb values than temperate ones. The ecological implications of different values of Tb and of S, including their relationship with organisms which are “r” or “K” strategists are briefly discussed.
Assessment of five cultivars of potato (Solatium tuberosum L.) in a competition diallel
Authors: BRADSHAW J E
Published: February 2008

In 1992 and 1993, potato cultivars Cara, Estima, Pentland Dell, Pentland Javelin and Torridon were assessed in all possible pairings in three consecutive drills, such that one member of the pair (the cultivar) was the centre‐drill, and the other member (the neighbour) was in the two adjacent drills. Each year the trial was a randomised complete block design with four replicates. Inter‐cultivar competition was present for height, total tuber yield, ware yield and dry matter content, but not for emergence and maturity. Cultivar heights and dry matter contents under inter‐cultivar competition and in pure‐stands were highly correlated, whereas for total and ware yields, the rankings of cultivars in pure‐stands were different from those under competition.

Pure‐stand yields were predicted for the two years separately because of year × cultivar and year × neighbour interactions. When the average total yield of the outer‐drills was used as a covariate to adjust centre‐drill yields to pure‐stands, predicted yields were closer to those observed than were yields under competition, but there was little improvement in the correlations. In contrast, not only were the predicted values even closer to the observed ones when based on individual neighbour effects, the correlations were much higher (r = 0.76–0.94). Unfortunately, in plant breeding trials with large numbers of entries, precise estimation of individual neighbour effects would require an unrealistically large number of replicates. Hence, for the final stages of yield assessment of new cultivars, it is still desirable to use multiple‐drill plots and to discard the outside drills where inter‐cultivar competition can occur.
Effect of pre‐storage treatments on mango fruit ripening
Authors: BURDON J N , DORI S , LOMANIEC E , MARINANSKY R , PESIS E
Published: February 2008

The effectiveness of pre‐storage treatments of nitrogen (low oxygen), heat and ethanol and acetaldehyde vapours were examined for their potential for improving mango storage. Mature green mango fruit (Mangifera indica L. cv. Keitt) were treated with low oxygen (< 3% oxygen, 97% nitrogen) for 72 h, acetaldehyde (0.12%) and ethanol (1%) vapours for 24 h or heat (38 ± 2°C) for 48 h prior to storage at 14°C. The nitrogen and ethanol treatments induced substantial levels of acetaldehyde and ethanol in the fruit. Initially the firmness of the nitrogen treated fruit remained higher than the control although later in storage this effect was lost. Differences in ripening were reflected in the total soluble solids and acidity levels, nitrogen maintaining a higher acidity and lower total soluble solids (less mature) whereas the heat treated fruit had lower acidity and higher total soluble solids (more mature). Ethanol and acetaldehyde treatments showed no effect. The use of a pre‐storage treatment of nitrogen therefore had a beneficial effect on retarding ripening, although as storage progressed this effect was lost.
Improved procedures for the in vivo and in vitro production of conidial inoculum of Venturia species of pome fruit
Authors: ROBERTS A L , CRUTE I R
Published: February 2008

Full descriptions are provided of a set of improved in vivo and in vitro procedures to allow the efficient production and long‐term storage of conidial inoculum of Venturia species pathogenic on pome fruit. Uniform stands of seedlings inoculated and incubated under standard conditions are used to produce conidial inoculum in vivo, while production in vitro involves establishing a culture on the surface of sterile muslin saturated with 10% malt extract. Conidia retain viability following storage for at least 2 years at ‐20°C. These materials and methods are now used routinely for several types of investigation; they are described together in one publication for the first time and have been shown to provide some advantages over previously reported procedures.
Tuber surface microorganisms influence the susceptibility of potato tubers to late blight
Authors: CLULOW S A , STEWART HELEN E , DASHWOOD E P , WASTIE R L
Published: February 2008

Potato tubers (cvs Cara and Bintje) were grown in compost in a glasshouse and immature tubers harvested 57, 68 and 78 days after planting. Two moisture levels were imposed after the first harvest by disconnecting the water supply to one of the treatments and allowing the soil in that treatment to dry naturally. Tubers from wetter compost (59.4% moisture holding capacity) were more resistant to Phytophthora infestans than those from drier compost (14.7% moisture holding capacity) 78 days after planting. The potential causes of this difference were investigated. Aqueous extracts of wet compost did not inhibit the growth of P. infestans. The susceptibility of the internal tuber tissue, from which the periderm had been removed, was different to whole tuber susceptibility. The internal tissue of tubers from wet compost was more susceptible (cv. Cara), or as susceptible (cv. Bintje) as that of tubers from dry compost 78 days after planting. Fungi were isolated from the surface of whole tubers and there were no differences between the populations of potentially antagonistic fungal genera on tubers from wet and dry compost. As the experiment progressed, the number of bacteria per gram fresh weight on tubers grown in wet compost increased, whereas that on tubers from drier compost decreased (cv. Bintje) or remained similar (cv. Cara). There were significantly (P= 0.008) more bacteria on the surface of tubers from wet compost 78 days after planting. When P. infestans was co‐cultured in Petri dishes with randomly selected tuber surface bacteria, some isolates (≤ 16.7%) inhibited the growth of the fungus. The percentage of the total bacterial population that was antagonistic to P. infestans was not significantly affected by soil moisture level (P= 0.368). The greater numbers of bacteria, of which a proportion are antagonistic to P. infestans, on the surface of tubers grown in wet compost may account for the greater resistance to tuber blight in that instance.
Surveys of stem base diseases and fusarium ear diseases in winter wheat in England, Wales and Scotland, 1989–1990
Authors: POLLEY R W , TURNER J A
Published: February 2008

An investigation into the incidence of stem base diseases and the pathogens associated with them was undertaken on winter wheat samples collected at growth stages 31 and 73–75 in 1989 and 1990. Symptoms at growth stage 31 were classified into 10 different types based on visual characteristics. Although Pseudocercosporella herpotrichoides was associated mainly with eyespot lesions and Rhizoctonia spp. with sharp eyespot lesions, a significant number of isolates of each pathogen were taken from lesions classified as fusarium. Different types of fusarium lesion on stem bases at both growth stages were not associated with any one particular Fusarium or Microdochium species. 98% of P. herpotrichoides isolates obtained from eyespot lesions at growth stage 31 in 1989, and 87% of those obtained in 1990 were identified as the sub‐species P. herpotrichoides var. acuformis, Microdochium nivale was more common than any of the Fusarium species at both growth stages, and was particularly prevalent in samples from Scotland at the earlier growth stage in 1989. Isolations from the top internodes at growth stage 73–75 indicated that systemic infection by Fusarium species, although present in some stems, was of little importance. Fusarium ear blight affected 0.4% of ears in 1989 and 0.5% in 1990. Glume spot lesions on the ears in 1990 were predominantly associated with Fusarium poae.
Characterisation of a labile RNA virus‐like agent from white clover
Authors: GARDINER T J , PEARSON M N , HOPCROFT D H , FORSTER R L S
Published: February 2008

A labile virus has been identified in white clover in New Zealand. The virus was mechanically transmitted to nine species of herbaceous test plants. No virus‐like particles were identified by electron microscopy in ultrathin sections or in negatively stained sap extracts, although in infected Chenopodium quinoa there were prominent membraneous inclusion bodies in the cell cytoplasm and membrane‐bound structures c. 50 nm in diameter associated with the tonoplast in cell vacuoles. Double‐stranded RNA species of approximately 6800, 3500 and 3300 bp were isolated from infected tissues. DsRNA denatured by boiling was infectious to C. quinoa, but undenatured dsRNA was not infectious. Total nucleic acid preparations from infected leaves were highly infective without boiling, indicating that most of the infectivity was single‐stranded RNA. Infectivity was recovered in the poly (A)‐ faction following oligo (dT)‐cellulose chromatography, indicating that the RNA probably lacks a 3′ tract of poly (A). The labile white clover virus is tentatively named white clover virus L (WCIVL).