bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of maize streak virus antigens over time in different parts of maize plants of a sensitive and a so‐called tolerant cultivar by ELISA
Authors: PETERSCHMITT M. , QUIOT J. B. , REYNAUD B. , BAUDIN P. 
Published: February 2008

SummaryMaize streak virus (MSV) capsid antigens were detected over time in different parts of maize plants of a sensitive (INRA508) and a so‐called tolerant (“tolerant”) cultivar (IRAT297) using a direct or an indirect double antibody sandwich ELISA. Based on three types of experiments, it was shown that the antigens were distributed in the plant according to the age of the tissues. When the virus was inoculated on a particular leaf of 18‐day old plants with infective Cicadulina mbila, only the young leaves above the inoculated one were positive by ELISA but not the older ones below. The antigens could not be detected in the inoculated leaf. At day 3 after inoculation, the antigens were detected in the sheath and/or in the whorl of the third leaf above the inoculated one but not in the oldest part of the leaf, the unfolded lamina. Plants of the sensitive cultivar were inoculated at 9 days with C. mbila deposited in the whorl. At 23 h after inoculation, the antigens were detected in the sheath but not in the whorl which was found to be positive only at 32 h. On the basis of these results, a hypothesis of the mode of virus infection is proposed. Our results contribute to a better understanding of the relationship between the age of the plant at inoculation and yield loss as well as secondary infection. By transmission tests with C. mbila, it was shown that virus could only be acquired from leaves exhibiting symptoms. Virus concentrations were measured in plant samples by ELISA using a range of dilutions of purified virus. The virus concentrations were higher in the sensitive than in the “tolerant” cultivar, but no difference in antigen distribution was observed between the two cultivars. The “tolerant” cultivar appeared to be resistant to virus multiplication.
Hybridisation and fruit formation in macabo cocoyam (Xanthosoma sagittifolium (L.) Schott)
Authors: ONOKPISE OGHENEKOME U. , BOYA‐MEBOKA MARY , WUTOH JOSEPH G. 
Published: February 2008

SummaryStudies on the floral morphology of macabo cocoyam (Xanthosoma sugittifolium (L.) Schott) indicated that it required 50 to 70 days for flower formation while fruit maturity took 40 to 60 days after pollination. Among the three types of cocoyams (“white”, “red” and “yellow”), male flowers were more sterile in the “red” and “yellow” types. The spadix consisted of three parts, a bottom pistillate section, a central constricted region with sterile flowers separating the pistil from a third staminate section. The fruiting head formed as a result of hybridisation, is dome shaped and is comprised of a dense cluster of berries. Mean number of berries per fruiting head was 244 ± 40 while the weight of each head was 16.15 ± 6.38 gm. There were an average of 15 ± 6 seeds per berry with 100 seeds weighing 0.0266 ± 0.0048 gm. The longitudinally shaped seed is ridged and grooved like a pumpkin pod when observed under high magnification (400 ×)
Odour stimuli affecting autumn migration of Rhopalosiphum padi (L.) (Hemipter: ornoptera)
Authors: PETTERSSON JAN 
Published: February 2008

Summary R. padi gynoparae settling in the canopy of the winter host, Prunus padus, tended to form aggregations. Differences in the degree of exposure to wind, sun, etc., did not satisfactorily explain the aggregated pattern observed. In laboratory experiments, aphids did not distinguish between leaves taken from nearby aggregations and leaves taken far away from aggregations. The results of laboratory olfactometer tests and field trapping studies indicate that R. padi gynoparae produce an aggregation pheromone. Thus the aggregated settling pattern of gynoparae of R. padi can best be explained as a response to an aggregation pheromone.
Hatching of Globodera pallida juveniles by diffusate of potato genotypes, differing in tolerance to G. pallida
Authors: ARNTZEN F K , VISSER J H M , HOOGENDOORN J 
Published: February 2008

SummaryHatching induced by root diffusate, obtained from various potato genotypes, and by standard potato root diffusate, was determined in vitro. The used potato genotypes differed considerably in tolerance to Globodera pallida. A three parameter logistic model was used to describe the numbers of hatched juveniles in relation to time of exposure to root diffusate. Clear differences in hatching characteristics between genotypes were found. Some tolerant genotypes induced hatching of G. pallida juveniles relatively slowly, compared to intolerant genotypes. Other tolerant genotypes, however, induced hatching as fast as intolerant genotypes, and no significant correlation between hatching parameters and tolerance was found.
Crops that stay green1
Authors: THOMAS HOWARD , SMART CATHERINE M 
Published: February 2008

SummaryGenetic variation exists for foliar senescence and has, usually incidentally or empirically, been exploited for crop improvement. We review the incidence of delayed or inoperative senescence in maize, sorghum, oats, rice, wheat, fescue, soybean, french bean, fruit crops, trees and other species. The insights such variants give into the genetic control of leaf senescence, and the practical implications of improved understanding of the stay‐green phenomenon are discussed.
A simulation model of competition between winter wheat and Avena fatua for light
Authors: WEAVER S E , KROPFF M J , COUSENS R 
Published: February 2008

SummaryAn eco‐physiological simulation model of competition between A vena fatua and winter wheat (Triticum aestivum cv. Avalon) for light was parameterised and tested. The model simulates growth of each species, in kg dry matter ha“1day‐1, from sowing to maturity as a function of irradiance, temperature and various species characteristics. Parameter values were derived from the literature and from field experiments with each species grown in monoculture. Model performance was tested against 50:50 mixtures of the two species grown at two sites in southern England. Sensitivity analyses were performed in which the canopy height of each species and the density and time of emergence of A fatua were systematically varied while all other parameters were left unchanged. Accurate simulations of growth in mixtures depended upon an accurate description of the canopy height of each species throughout the growing season. Model predictions of winter wheat yield losses in relation to A fatua density and time of emergence showed good agreement with previously published data.
Infection of wild and cultivated Vaccinium spp. with blueberry leaf mottle nepovirus
Authors: SANDOVAL C R. , RAMSDELL D C. , HANCOCK J F. 
Published: February 2008

SUMMARYA field survey was performed during the summers of 1991 and 1992 to determine whether blueberry leaf mottle virus (BLMV) infects wild blueberry bushes surrounding commercial blueberry fields and might act as a reservoir of the virus. Leaf samples from wild blueberries growing in wooded areas surrounding commercial plantings in Western central Lower Michigan were taken from bushes radiating out from the border of the commercial field into the wooded areas at 5, 50 and 100 m. BLMV was present in native bushes of Vaccinium corymbosum, V. myrtilloides and V. angustifolium, and two hybrids of V. corymbosum V. angustifolium. BLMV‐infected pollen grains were detected in pollen traps located up to 2 miles from a source field.
Survival and seed to seedling transmission of Alternaria linicola on linseed
Authors: VLOUTOGLOU I. , FITT B. D. L. , LUCAS J. A. 
Published: February 2008

SummaryAlternaria linicola survived as thick‐walled chlamydospores in hyphal or conidial cells on infected linseed stem debris, either on the soil surface or buried in the soil, during the period between the harvest of linseed and sowing of the following crop (September ‐ April). Conidia produced on these debris under favourable conditions were not only viable but also pathogenic to young linseed seedlings. Infected stem debris increased the incidence of infected seedlings which emerged from infected seed (incidence of A. linicola 1% to 28%), especially if the debris was on the soil surface rather than buried. A. linicola also survived between successive linseed crops on infected volunteer linseed plants which survived the low temperatures in winter and on the weed Veronica persica. A. linicola was more effectively transmitted from infected seeds to seedlings at temperatures 15–25°C than at 10°C. The incidence of the disease on seedlings which emerged from infected seed was positively correlated with the amount of seed‐borne inoculum, whereas the proportion of seedlings which emerged was negatively correlated with the incidence of A. linicola on the seed.
Variation in the occurrence of rust (Melampsoraspp.) and other diseases and pests, in short‐rotation coppice plantations ofSalixin the British Isles
Authors: HUNTER T. , ROYLE D J , ARNOLD G M 
Published: February 2008

Summary.A proportional odds model was employed to analyse simple assessments of disease and pest severity in plantings of short‐rotation coppice willows at 18 sites in the UK over a 5‐year period (1987–1991). Of a wide range of fungal diseases and pests encountered, the most severe and damaging were rusts, caused byMelampsoraspp., and feeding damage due to beetles of the family Chrysomelidae. For rust, the model revealed highly significant (P< 0.001) interactions between the main factors, disease development within a season and between seasons, clones and sites. Within seasons, rust severity increased more at sites in the northern than in the southern UK, due mainly to low levels of occurrence at the northern sites early in the season. There was a gradual increase in rust severity over the 5‐year period, although clones differed both in terms of disease severity and the extent of change in severity in any one year. Beetle feeding damage was also analysed in a similar way, indicating a general increase from 1987–1989, but also revealing differential patterns over time and between sites.
The potential of hemp (Cannabis sativa L.) for sustainable fibre production: a crop physiological appraisal
Authors: WERF HMG VAN DER , MATHUSSEN E W J M , HAVERKORT A J 
Published: February 2008

Summary.Hemp (Cannabis sativa L.) fibre can be used as a raw material for paper and textile production. A comprehensive research programme in the Netherlands has concluded that fibre hemp is a potentially profitable crop, having the right profile to fit into sustainable farming systems. This paper presents an appraisal of the crop physiological characteristics and the agronomic potential of hemp. Parameter values of basic crop physiological characteristics such as light interception potential, radiation use efficiency and dry matter partitioning coefficients are given. The effect of crop management decisions such as cultivar choice, sowing date, plant density, and harvest date on the value of these parameters is discussed. A simple crop growth model was used to assess the yield potential of hemp for the climate of the Netherlands. Calculations made for a non‐stressed late‐flowering hemp crop sown on 15 April and harvested on 15 September give a stem dry matter yield of 17.1 t ha‐1. The effects of advancing or delaying sowing or harvest date on stem yield were calculated. Crop physiological characteristics of hemp are compared to those of kenaf (Hibiscus cannabinus L.). Radiation use efficiency and dry matter partitioning coefficients of the two crops are similar. Base temperatures for development and growth are lower in hemp than in kenaf. In a temperate climate with cool springs, canopy establishment will be more rapid in hemp than in kenaf. Hemp seems an excellent candidate to fill the niche for an annual fibre crop in a temperate climate.
Crop borders reduce potato virus Y incidence in seed potato
Authors: DIFONZO C D , RAGSDALE D W , RADCLIFFE E B , GUDMESTAD N C , SECOR G A 
Published: February 2008

Summary.Crop borders of soybean (Glycine max), sorghum (Sorghum bicolor), winter wheat (Triticum aestivum) and potato (Solanum tuberosum) were tested as a means of reducing potato virus Y (PVY) incidence in seed potato. Borders of fallow cultivated ground served as controls. Aphid landing rates were monitored weekly in plots using green tile traps, and PVY incidence was assessed by serologically testing tuber progeny from selected rows in each plot. Average weekly aphid landing rates in fallow‐bordered and crop‐bordered plots were not significantly different in 1992 (29.4 and 25.2 aphids, respectively) or 1993 (7.3 and 6.6 aphids, respectively). However, crop borders significantly reduced PVY incidence. In 1992, fallow‐bordered and soybean‐bordered plots averaged 47.8% and 35.0% PVY infection, respectively. In 1993, PVY infection averaged across all crop (soybean, sorghum, and wheat) bordered plots was 2.7% compared to 6.8% in fallow‐bordered plots. PVY incidence in the centre rows of fallow‐bordered and crop‐bordered plots was statistically equivalent, while outer rows of crop‐bordered plots had significantly less PVY than outer rows of fallow‐bordered plots. Crop borders apparently reduced the number of viruliferous aphids landing on the edge of the plot. The choice of crop species used as a border, or treating the border with a systemic insecticide, did not affect aphid landing rates or PVY incidence. In 1995, PVY incidence in the centre 10 row block of potatoes averaged 2.1% across all crop borders (potato and soybean). PVY infection in the four row potato border averaged 5.7%. Crop borders are readily adaptable to current production practices, although the greatest benefits in reducing PVY incidence would occur in average sized, generation 0 (< 0.2 ha), elite seed potato fields.
Prediction of a low dose herbicide effect from studies on binding of metribuzin to the chloroplasts of Chenopodium album L.
Authors: KETEL D H. , WIELEN M J W VAN DER , LOTZ L A P. 
Published: February 2008

SummaryChenopodium albumL. seedlings at the 4‐ and 8‐leaf stage were exposed to low concentrations metribuzin [4‐amino‐6‐(l, l‐dimethyl)‐3‐(methylthio)‐l,2,4‐triazin (4H)‐one] in nutrient solution to study herbicide uptake and the effects of low‐dose rates. Chlorophyll fluorescence was measured to relate the inhibition of photosynthesis to herbicide dose. The minimum rate at which metribuzin fully inhibited photosynthesis was less than 1μMfor seedlings at the 4‐leaf stage of development, and between 1 and 5μMfor the 8‐leaf stage seedlings. With isolated chloroplasts, experiments were conducted to establish the relationship between the amount of herbicide molecules bound to each chloroplast and the inhibition of photosynthesis. From the dose‐response curves obtained it was calculated that photosynthesis was fully inhibited when 7.5 105molecules metribuzin were bound to each chloroplast. This amount of binding was used to estimate minimum‐lethal dose rates of metribuzin required for seedlings differing in fresh weight of leaves and amounts of chloroplasts present. It is suggested that prediction of a low dose herbicide effect from studies on binding of photosystem‐II inhibitors in combination with chlorophyll fluorescence measurements may lead to the development of a new weed management strategy.
Elimination of apple stem grooving virus by chemotherapy and development of an immunocapture RT‐PCR for rapid sensitive screening
Authors: JAMES D. , TRYTTEN P A , MACKENZIE D J , TOWERS G H N , FRENCH C J 
Published: February 2008

SummaryOmbuin (7,4′‐dimethyl quercetin) (10 μg ml‐1, for 12 wk), glycyrrhizin/quercetin (80 μg ml‐1and 10 μg ml‐1respectively, for 18 wk), ribavirin (10 μg ml‐1, for 12 wk) and quercetin/ribavirin (10 μg ml‐1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT‐PCR, and immunocapture RT‐PCR. A sensitive immunocapture RT‐PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.
The effect of the CpTi gene in strawberry against attack by vine weevil (Otiorhynchus sulcatusF. Coleoptera: Curculionidae)
Authors: GRAHAM J. , GORDON S C. , McNICOL R J. 
Published: February 2008

SummaryThe degree of protection against insect feeding conferred upon transgenic strawberry lines expressing the Cowpea trypsin inhibitor was evaluated under glasshouse conditions. Insect bioassays were carried out using vine weevil (Otiorhynchus sulcatus) in two experiments and in both experiments there was a highly significant reduction in damage by weevil larvae on the transgenic lines.
Arable weeds identified as new sources of beet mosaic potyvirus in Greece
Authors: KATIS N J , KOKINIS G. , ELEFTHEROHORINOS I. , JONES P. 
Published: February 2008

SummaryField and laboratory studies were carried out between 1992 and 1994 to assess the potential for arable weeds to act as reservoirs of beet mosaic potyvirus (BtMV) in fields where sugar beet is cultivated for seed. 933 weed samples were collected and tested by biological methods, while a representative number of weeds were tested by serological methods. The results showed that 97 samples, representing 14 weed species from eight families, were infected with BtMV. The following weeds were found to be naturally infected with BtMV for the first time: Bilderdykia convolvulus, Nonea pulla, Cerastium glomeratum, Galium aparine, Conyza (Erigeron) spp., Fumaria officinalis, Heliotropium europaeum and Rumex spp. The most common weeds found to be infected with BtMV in high percentage were members of the Papaveraceae.
The effect of field margins on the yield of sugar beet and cereal crops
Authors: SPARKES D L , JAGGARD K W , RAMSDEN S J , SCOTT R K 
Published: February 2008

SummaryThe effect of field margins on the yield of sugar beet, wheat and barley was studied on commercial farms and in a series of field experiments from 1992–1997. There was always a trend of increasing yield from the edge of the field to the centre, with a marked reduction around the ‘tramlines’ and the area where machinery turns. In the studies on commercial farms, headland yield loss varied widely. In sugar beet the headlands yielded 19–41% less than the centre, with a mean reduction of 26%. In cereals the range was 3–19%, with a mean loss of 7%. Headland yield reductions were generally smaller in the field experiments than those found on commercial farms. These headland effects did not move towards the centre of the field when grass margins were planted at the edge of the field; there was no significant effect on the yield of the adjacent crop. The presence of boundary trees had the greatest effect on yield: in the outer 9 m of the field, the area shaded by trees produced 4.4 t ha‐1 of wheat, and the area that was not shaded 8.1 t ha‐1. Turning of machinery also significantly reduced yield, while grazing by rabbits and hares surprisingly had no effect.Following the reform of the Common Agricultural Policy in 1992, the main effect of which was to change from a price support policy to direct payments to producers, farmers in the European Union who produce more than a specified tonnage of ‘eligible crops’ per year, are required to fallow a given percentage of their land (currently 5%), to qualify for Arable Area Payments. Growers can elect to fallow fields on a rotational basis, or permanently. Headland set‐aside is a term used to describe strips of set‐aside, a minimum of 20 m wide around the edges of fields. In these experiments, the headland effect did not extend beyond 20 m from the field edge. Therefore, particularly in fields with boundary hedges or trees, headland set‐aside could effectively remove the poor‐yielding area at the field margin.
Intercrops, Cicadulina spp., and maize streak virus disease
Authors: PAGE W. W. , SMITH M. C. , HOLT J. , KYETERE D. 
Published: February 2008

SUMMARYIntercrops of bean and finger millet were tested as a possible means of controlling maize streak virus disease (MSVD) in maize by disrupting the mating behaviour of the insect vectors of the maize streak virus, Cicadulina mbila and C. storeyi. A series of three trials were done. In the first, MSVD incidence 2 months after sowing was reduced to 14.9% and 17.4% in millet and bean intercrops compared to 29.5% in the pure maize stand. The number of male Cicadulina spp. caught on sticky pole traps was also significantly reduced relative to the control, but there was little effect on the catch of females. There was no significant yield penalty for the millet intercrop but maize yield was 49% lower in the bean intercrop treatment than in the pure stand. In the second trial, there were two millet and two bean intercrop treatments and a maize only control. Fewer male Cicadulina spp. were caught in the intercrop treatments relative to the control but MSVD incidence was reduced in one millet intercrop treatment only for which the associated maize yield penalty was 89%. In the final trial the bean intercrop was again tested but it had no effect on MSVD incidence. These experiments demonstrated that intercropping maize with bean or millet decreased vector activity and/or vector numbers. Vector catches were predominantly male, and catches of males but not females were reduced in the intercrop treatments compared with pure stands. However the lower vector catch was not consistently associated with a significant reduction in MSVD incidence, and when it was there was often an associated yield penalty in the maize due to the intercrop.
An investigation of the frost hardiness of grapevine(Vitis vinifera)during bud break
Authors: FULLER M. P. , TELLI G. 
Published: February 2008

SUMMARYThe aim of this investigation was to assess ice nucleation and frost resistance of two varieties of grapevine (Siegrebbe and Madeleine Angevine) during bud burst under radiative freezing conditions analogous to those during Spring in the UK.During bud burst, grapevines were almost entirely resistant to freezing during frosts of less than ‐3°C by virtue of their ability to supercool. The risk of frost damage increased significantly as bud development progressed, and once buds had passed growth stage DS3 they became more sensitive to freezing and freezing damage was more extensive. The two varieties did not differ in frost resistance but, because of its earlier developing habit, variety Siegrebbe could be more prone to frost damage in the field.Buds were more prone to damage after freezing once bud burst had commenced and the damage could not be reversed by acclimating plants for periods of 7 to 21 days at 4°C in an 8 h photoperiod. Such acclimation appeared to predispose frozen buds to more extensive damage.