bluuebunny/crossref_metadata_2025 huggingface dataset:
Triple test cross predictions of the performance of recombinant inbred lines from a wide cross in onions (Allium cepa)
Authors: WERNER C. P. , DOWKER B. D. , DeSOUZA D. C. , SETTER A. P. , CROWTHER T. C. , HOROBIN J. F.
Published: February 2008

In conjunction with an onion breeding scheme to produce recombinant inbred lines from a wide cross genetical experiments were carried out to predict the likely outcome. Results are given of genetical predictions, obtained from two triple test cross experiments, of the expected performance of inbred lines derivable by single seed descent from a Japanese × Polish cross. For bulb maturity, c. 12% of the inbred lines are expected to be earlier than the earlier parent; for bulb hardness over 50% of the inbred lines are expected to exceed the better parent. For bulb weight, predictions from the basic model suggest 5–25% of the inbred lines may exceed the better parent, but when this model is modified to take account of the likely inbreeding depression in the open‐pollinated Japanese parent, only 0–2% of such high yielding inbred lines are expected. Other potential sources of bias which may affect the predictions are discussed.
Ontogenic variation in nitrogen assimilation, nodulation and nitrogen fixation in groundnut (Arachis hypogaea) genotypes*
Authors: DUTTA M. , RAO B. SRINIVASA , NAMBIAR P. T. C. , WILLIAMS J. H. , DART P. J.
Published: February 2008

Seasonal pattern of acetylene reduction (AR) and shoot nitrogen accumulation was studied in nine groundnut cultivars. Shoot N accumulation by all the cultivars was maintained until shortly before maturity and it occurred faster over the reproductíve growth phase than over the earlier phases. In all cultivars plant AR (PAR) did not reflect this pattern of N accumulation, being greater over the vegetative and pod initiation phases. This suggests that the commonly observed low PAR values for groundnut over the reproductive growth phase may be the result of factors other than sink competition.

There were significant interactions of cultivar with stage of crop growth for PAR, nodule mass, and specific nitrogenase activity (SNA). Virginia types generally showed better nodulation, higher N2‐fixing capacity (both PAR and SNA) than valencias, and significant differences were observed between cultivars within a botanical type.
A vertical band‐Dutch harrow technique for incorporating granular nematicides in soil to control potato cyst‐nematodes, Globodera rostochiensis and G. pallida
Authors: WHITEHEAD A. G.
Published: February 2008

In lightly infested silt loam, aldicarb at 3·3 kg ha‐1in 1985 or oxamyl at 4·5 kg ha‐1in 1986, applied to the top 12 – 15 cm of the soil by a 5 m wide Dutch harrow fitted with vertical band granule outlets 15 cm apart, increased yields of King Edward or Romano potatoes and effectively controlled increase of potato cyst‐nematodes. Carbofuran at 5 kg ha‐1in 1986 was less effective.

This new vertical band‐Dutch harrow technique has the advantage over the vertical band‐rotary harrow technique in that lateral mixing of the vertical bands of granules is not required. It is especially useful for poorly structured soils, which will not tolerate powered harrowing, and could also prove beneficial on other soils of low organic matter content.
The effects of some commonly‐used foliar fungicides on Collembola in winter barley: laboratory and field studies
Authors: FRAMPTON G. K.
Published: February 2008

Four commonly‐used cereal foliar fungicides were screened for their laboratory toxicity against the symphypleone collembolan, Sminthurinus aureus. A proportional hazards analysis of time‐survival curves following the fungicide treatments showed that carbendazim, propiconazole, pyrazophos and triadimenol significantly increased the laboratory mortality of S. aureus. The organophosphorus fungicide pyrazophos caused high levels of mortality of S. aureus in the laboratory so a field evaluation of the effects of this fungicide on a wider range of Collembola was undertaken in winter barley.

Comparison of the effects of pyrazophos with those of the broad‐spectrum insecticide dimethoate in the field revealed both compounds to have similar activity against some Collembola. Of the 11 species caught only the four symphypleone species exhibited these effects but the numbers of three symphypleone species were reduced to zero 4 wk after treatment with pyrazophos. The effects of pyrazophos and dimethoate were, however, not detectable in individual species after 11 wk.
Activity of triadimefon vapour against Erysiphe graminis f. sp. hordei
Authors: JENKYN J. F. , WHITE N.
Published: February 2008

A series of experiments from 1978 to 1983 investigated the activity of triadimefon vapour against barley powdery mildew (Erysiphe graminis f. sp. hordei). In early experiments there was a pronounced protectant action when the dry product was used as the vapour source, and this protection persisted after test seedlings had been removed from the vicinity of the vapour source. In a glasshouse, sprayed seedlings remained sources of active vapour for at least 6 wk after spraying. In later experiments, effects of triadimefon vapour were much smaller, probably because the pathogen had become less sensitive to the fungicide. The dry product was no longer an effective vapour source but infection of test seedlings was still decreased if they were exposed to vapour emanating from impregnated absorbent paper or sprayed seedlings, presumably because the effective surface areas were much greater. Possible benefits and problems that arise from vapour action in glasshouse and field experiments are discussed.
The transmission of potato virus Y by aphids of different vectoring abilities
Authors: GIBSON R. W. , PAYNE R. W. , KATIS N.
Published: February 2008

Adult apterae of Myzus persicae and Macrosiphum euphorbiae that did not transmit potato virus YN (PVYN) in a first test were as likely to transmit the virus in a subsequent test as those that did transmit on the first occasion. Only 16% of M. persicae that were allowed a single acquisition probe into a leaf infected with both PVYO and PVYN transmitted both strains, 37% transmitted either PVYO or PVYN and 47% did not transmit. There was no difference in the duration of probes that did or did not result in virus transmission. Statistical models were fitted to data on the frequency of transmission of PVYO, PVYN or both PVYO and PVYN by M. persicae and by aphids of poorer vector species, M. euphorbiae and Rhopalosiphum padi. Transmission of the two viruses ocurred independently of each other and consequently transmission of both was rare with M. euphorbiae and R. padi. Mineral oil applied to leaves infected with both strains diminished the frequency of transmission by M. persicae. Fitted models suggested that the aphids that probed through the oil droplets on leaves treated 30 min previously did not transmit virus, and that 24 h later, when the droplets had spread, aphids probing through them could transmit but with a decreased ability.
The effect of the weight of the seedling‐derived tuber on subsequent clonal generations in a potato breeding programme
Authors: BROWN J.
Published: February 2008

Two experiments are reported. In the first, the weight of seed tuber planted in the first clonal year was examined in relation to clonal performance in the first three clonal generations. The weight of seed tuber planted in first clonal year influenced breeders' preference scores and yield characteristics in the first, second and third clonal generations thus suggesting that size of tuber produced by seedlings is in part genetically controlled. The relationship between weight of seed tuber produced by seedlings and clonal performance was, however, reduced with increasing generations from true seed. In the second experiment, the size of seed tubers produced was manipulated by growing seedlings in different sized pots. When seedlings were grown in small pots (2.5 cm) first‐clonal‐year plants produced low yields of small tubers. In contrast, when larger pots were used to raise seedlings, first‐clonal‐year genotypes gave higher yields and were given greater preference scores. Hence, performance of genotypes in the first clonal year was dependent on the size of pot used to raise seedlings. After the first clonal generation however, clonal performance was not influenced by the size of pot used at the seedling stage. The overall conclusion was that, although the size of tuber produced by seedlings had a genetic component, the largest effect of seed tuber size used in the first clonal year was non‐genetic and would adversely influence efficiency of selection for yield, yield components and breeders' preference in the early generations of a potato breeding programme.
Field and glasshouse studies on components of resistance to root fly attack in swedes
Authors: BIRCH A. N. E.
Published: February 2008

Field trials in two years indicated that egg‐laying antixenosis was the major component of resistance in swede cvs Angus and Melfort against root flies (Delia floralis and D. radicum). Between four and eight times as many D. floralis eggs were laid on the susceptible cv. Doon Major as on the resistant cv. Angus. The degree of antixenosis effective against D. radicum was more variable in 1985, due to low numbers of adult flies, but in 1986, when adult fly numbers were higher, D. radicum laid 34 times as many eggs on susceptible cv. Sator Øtofte as on Angus.

Root antibiosis against larval feeding is a second but less important component of resistance against D. floralis. In egg inoculation tests, 1.3‐2.0 times more D. floralis pupae developed on Doon Major than on Angus or Melfort. Larval feeding on resistant cultivars was restricted to surface root tissue only, compared with deeper tunnelling on susceptible cultivars. Tolerance to root damage may also occur under certain conditions. Although increased dry matter content was significantly correlated with root antibiosis, its effect on larval feeding was apparently not due to increased tissue hardness. It seems likely that chemical differences in the outer root tissues influence larval feeding and development.
Aerial application of mixed virus formulations to control joint infestations of Panolis flammea and Neodiprion sertifer on lodgepole pine
Authors: DOYLE C. J. , ENTWISTLE P. F.
Published: February 2008

An aerial spray using mixed formulations of two viruses, Panolis flammea nuclear polyhedrosis virus (NPV) and Neodiprion sertifer NPV was conducted against mixed populations of the two pests, P. flammea and N. sertifer on lodgepole pine. These were compared with single virus formulations sprayed against their respective host pests and an unsprayed control. One hectare plots of 14 yr old pine were sprayed by helicopter using ultra low volume techniques. Larvae from each plot were assessed weekly for virus and this showed that the mixed formulations gave the same level of control as separate applications of each NPV. Levels of infection in P. flammea reached 95 – 100% 9 wk post‐spray, and in N. sertifer reached 100% 6 wk post‐spray. Later P. flammea pupal sampling showed no viral infection in the control but significant levels in sprayed plots, which ranged from 37–9% in the plot sprayed with the high dose of N. sertifer NPV to 75% in the plot sprayed with the low dose of NsNPV.
Promotion and inhibition by ethylene of chlorophyll degradation in orange fruits
Authors: KNEE M. , TSANTILI ELENI , HATFIELD S. G. S.
Published: February 2008

The effect of ethylene concentration on chlorophyll destruction in orange (Citrus sinensis cV. Washington Navel) fruits was examined at 15 °C and 25 °C. The reflectance of the fruits at 680 nm was measured, and the results converted to chlorophyll concentrations through an empirically derived formula based on the Kubelka‐Munk equation. In all ethylene treatments chlorophyll destruction was faster at 25 °C than at 15 °C and all ethylene concentrations tested increased the rate of loss at 25 °C. At 15 °C the highest rate of chlorophyll destruction was observed at 1 μl litre‐1 ethylene, while chlorophyll loss at 1250 μl litre‐1 was slower than in untreated fruits.
Enhancing the performance of ethephon with mepiquat chloride on barley (Hordeum distichon cV. Panda) using an adjuvant comprising acidified soyal phospholipid
Authors: GREEN C. F. , CHALMERS I. F. , PACKE‐DRURY‐LOWE J.
Published: February 2008

Rates of ethephon with mepiquat chloride (as ‘Terpal’) were foliar applied to winter barley during early flag leaf emergence with or without soyal lecithin acidified with proprionic acid included as an adjuvant (‘LI700’). In both the glasshouse and field increasing the rate of ‘Terpal’ decreased the rate of stem extension exponentially, which in turn led to progressively shorter stands.

As crop height extended above 0.9 m both the proportion of crop area lodged and the severity of lodging (mean angle of culms to the vertical) increased. As lodging progressed, mean grain weight was depressed and therefore ethephon with mepiquat chloride had the potential to increase yield. However, in the absence of lodging, applications of ‘Terpal’ reduced yield in direct proportion to increasing the dose rate. The influence of ‘Terpal’ on yield becomes a complex interaction between phytotoxicity, probably resulting from exogenous ethylene applications and benefits accruing from the control of lodging.

Adding ‘LI700’ as an adjuvant enhanced the performance of ‘Terpal’ in reducing both rate of stem extension and mean grain weight in the absence of lodging.
The response of field‐grown lucerne to a manipulated range of insect‐induced nitrogen stresses
Authors: GOLDSON S. L. , JAMIESON P. D.
Published: February 2008

G. W. BOURDOT*

The growth of a 1‐yr‐old lucerne (Medicago sativa) stand subjected to nitrogen stress was analysed using a simple model that related growth to intercepted photosynthetically active radiation (PAR). Nitrogen stress was systematically induced by establishing a range of populations of Sitona discoideus (Coleoptera: Curculionidae) larvae in the stand. The direct influence of their feeding on the plants' nitrogen‐fixing root rhizobial nodules was confirmed by the strong linear relationship found between larval density and herbage nitrogen concentration (N%). The negative effect of nitrogen stress on herbage production was found to become abruptly apparent at an N% level of 4–7%. Eighty‐seven percent of the loss in dry matter production in the nitrogen‐stressed plants was associated with a decline in the ability of the canopy to use PAR, rather than a reduction in the amount of PAR intercepted.

From the results obtained it was concluded that the damage effects of S. discoideus larvae were less drought‐related than initially thought. It is speculated that the abrupt onset of damage occurred when the re‐establishing rhizobial root nodule population demanded more nitrogen than it fixed.
The relationship between fruit retention force at harvest and quality of feijoa after storage
Authors: DOWNS CHRISTOPHER G. , PICKERING ANA E. , REIHANA MAKARETA , O'DONOGHUE ERIN M. , MARTIN WILHELMINA
Published: February 2008

Feijoa (Feijoa sellowiana, cvs Apollo and Gemini) fruits were removed from the tree and grouped into treatments according to retention force (RF) at harvest. Fruits with greater RF at harvest had higher titratable acidity and flesh firmness, lower soluble solids content and less locule clarity at harvest than fruits with lower RF. After 4 wk storage at 4 °C and 5 days shelflife at 20 °C titratable acidity, soluble solids and firmness in these fruits were similar across RF grades except that after shelflife the incidence of flesh and locule browning was greater in fruits harvested with low RF when compared with fruits picked with greater force. At harvest the total sugar and organic acids, and the sugar: acid ratio were similar irrespective of RF, whereas after storage and shelflife no consistent effect of RF existed.

Taste panellists could not detect differences in the eating appeal of fruit harvested with high or with low retention force after storage and shelflife. Soluble solids, acidity and flesh firmness declined markedly over storage and shelflife irrespective of retention force at harvest and although these fruits were still acceptable for eating, they no longer had the characteristic flavour and texture of unstored feijoas.
Review of recent research on navy beans (Phaseolus vulgaris) in the United Kingdom
Authors: HARDWICK R. C.
Published: February 2008

Navy beans are the raw material for ‘baked beans’. Since the 1960's a number of workers have attempted to introduce the crop to the United Kingdom. The paper reviews the results of research to date.

In favoured areas of the United Kingdom yields of 300 g seed/m2may be expected in small‐plot trials. The optimum plant spacing is between 20 and 30 plants/m2and dressings of about 150 kg/ha of N fertiliser are required for maximal yield. The nitrogen fertiliser may be dispensed with, at the cost of a small reduction in yield, if the seed is inoculated with an elite strain ofRhizobium phaseoli.

In the United Kingdom the potential diseases of the crop include halo‐blight (Pseudomonas syringaepV.phaseolicola), bean common mosaic virus, and anthracnose (Colletotrichum lindemuthianum).Genetic sources of resistance have been identified, and they are incorporated in some of the UK‐bred material.

It seems likely that the varieties with improved adaptation and disease resistance that are now available from the UK work will be useful to farmers in continental Europe. For the UK itself, some improvements in cold‐tolerance and yield stability may still be required.

The paper concludes with a discussion of the lessons to be learned from the project.
Occurrence, growth and survival of Aphis craccivora (Homoptera: Aphididae) on some weeds in a rain forest area of Nigeria
Authors: OFUYA T. I.
Published: February 2008

Twenty‐five weed species that commonly infest farmlands in Ondo, Nigeria were sampled monthly in 1985 for Aphis craccivora. The aphid was found on Euphorbia hirta, E. glomifera and Boerhaavia diffusa, mainly during the off‐seasons of the principal host plants.

In the laboratory, A. craccivora reared on Vigna unguiculata showed lower progeny mortality, and produced heavier and more fecund females than those reared on any of the three alternative weed hosts. Progeny mortality was also lower, and adult weight higher, on B. diffusa than on the Euphorbia weeds.
Chemical control of frit fly on winter cereals sown after grass
Authors: FRENCH N. , NICHOLS D. B. R. , WRIGHT A. J. , GREEN D. I. , GREEN D. B. , FENLON J. S.
Published: February 2008

From 1978 ‐ 1985, 14 trials were conducted, mainly in Northern England, to assess the efficacy of different insecticides, formulations and application times for the control of frit fly (Oscinella frit) on winter cereals (13 on winter wheat and one on winter barley). Treatments were compared by assessing shoot damage in December‐January, numbers of healthy tillers in April and harvested yield. A chlorpyrifos spray to the grass before ploughing or at crop emergence gave the most consistently good results, significantly reducing damage and increasing yield by 0·61 and 0·31 t/ha respectively when taken over all trials. Sprays or granules of other insecticides applied from before drilling to 8 wk after emergence gave variable but sometimes good control and enhanced yield. Chlorpyrifos applied from crop emergence to 8 wk after emergence was generally more effective than other insecticides. Cypermethrin at emergence or 2wk later gave promising results in the two trials where it was used. Of the seed treatments fonofos was the most effective though it did not match the spray treatments.

In additional trials, where insecticides were applied after damage occurred, sprays of chlorpyrifos and pirimphos‐methyl reduced damage and increased yield.
Control of apple canker using fungicidal paints and gels
Authors: COOKE LOUISE R. , McCRACKEN A. R.
Published: February 2008

Paints containing mercuric oxide or thiophanate‐methyl were applied to either scraped or unscraped cankers caused by Nectria galligena on apple trees at two sites. Three gel formulations (carbendazim/triadimefon in alginate or xanthan and carbendazim/imazalil in xanthan) and a solvent‐based PP969 formulation were applied to unscraped cankers only. Assessments were made 9 and 21 months after treatment. Mercuric oxide was more effective than thiophanate‐methyl after 21 months on both scraped and unscraped cankers. All gel formulations reduced spore production and fungitoxicant could still be detected in bark and wood after 21 months. The solvent‐based PP969 formulation did not perform as well as the gels.
Effects of potato leafroll virus on the crop processes leading to tuber yield in potato cultivars which differ in tolerance of infection
Authors: MARSHALL B. , BARKER H. , VERRALL SUSAN R.
Published: February 2008

The effects of infection with potato leafroll virus (PLRV) on the four crop processes leading to tuber fresh weight yield were examined in field plots of four cultivars (Montana, Pentland Crown, Maris Piper and King Edward) differing in tolerance to infection. Averaged across cultivars, infection decreased yield by 50%. This decrease was equally due to less light (total solar radiation) being intercepted, a lower efficiency with which intercepted light was converted into dry weight, and a smaller proportion of dry weight being partitioned to tubers. Dry matter content of the tubers was also diminished but to a lesser extent. The main difference between the cultivars in their response to infection was in the partitioning of dry weight. In Montana and Pentland Crown, harvest index was decreased by 15% in infected plants, whereas in the less tolerant cultivars, Maris Piper and King Edward, it was decreased by 25%. The decline in photosynthetic performance of Montana, a cultivar with slightly earlier maturity than the other three, was delayed in PLRV‐infected plants. Effects on number of daughter tubers essentially reflected those on yield to the extent that average tuber weight did not change in Maris Piper, was one third less in King Edward, and the change was intermediate in Montana and Pentland Crown.
Laboratory evaluation of a toxicant‐sterilant, alpha‐chlorohydrin, for the control of Indian mole rat Bandicota bengalensis
Authors: SAINI MANJIT S. , PARSHAD V. R.
Published: February 2008

A toxicant‐sterilant, alpha‐chlorohydrin, was evaluated against the Indian mole rat Bandicota bengalensis and the ship or house rat Rattus rattus. It caused 100% mortality of B. bengalensis at 100 mg/kg but no mortality was observed in R. rattus even at 300 mg/kg. The acute oral LD50 for B. bengalensis was found to be 82 mg/kg. The survivors of B. bengalensis, which received 60 ‐ 90 mg/kg of alpha‐chlorohydrin by oral intubation, showed dose‐dependent decreases in testicular weight, and cauda epididymal sperm concentration, live sperm count and sperm motility. The values of these parameters indicated that mole rats receiving the above doses would be sterile. In contrast, these changes were observed in R. rattus only at doses of 200 and 300 mg/kg. The toxic and antifertility effects of alpha‐chlorohydrin observed on B. bengalensis suggest that it should be evaluated for the management of this species under held conditions.
A census of seedling establishment in sugar‐beet crops
Authors: DURRANT M. J. , DUNNING R. A. , JAGGARD K. W. , BUGG R. B. , SCOTT R. K.
Published: February 2008

Analysis of seedling establishment in 254 experiments from 1970 to 1977 showed that the target of 70%, needed for an adequate plant population and maximum yield, was achieved in only 19% of fields. However, because the plants were only counted once, when they had about six leaves, the cause and timing of the losses could not be identified. This, therefore, gave no sound basis for seeking improvements. Eight studies of all phases of establishment, from sowing to the 6‐leaf stage, were then made at Broom's Barn from 1978 to 1981. The studies were on sandy loam or clay loam soils with seedbeds prepared by standard, recommended methods and sown either early or late in spring. These standard treatments were supplemented by plots which tested irrigation or protection from rain, fine or coarse tilths, and the use of a soil applied insecticide or a sterilant. Despite the widely differing weather experienced by these crops, 70% establishment was achieved in seven studies; in the eighth, seedlings emerged at 75% of seed stations, but 31% were then killed, mainly by birds.

On average, the drill failed to place seeds at 2·8% of target positions, dead seed was sown at 6%, seedlings died after germination but before emergence at 12·4% and plants died thereafter at 6·5%. Almost every viable seed sown in the field germinated eventually; waterlogging seemed to be the cause of failure in a few small areas where this was not so. In most studies the first 50% of seeds germinated as expected on the basis of the thermal time required in the laboratory test. The remainder sometimes took longer, mainly because they experienced periods when the water supply was inadequate.

Seedlings failed to emerge for several reasons; of which the principal ones were dehydration, restriction under a soil crust or stone, and pest damage. It seemed that waterlogging and herbicide damage were important causes in a few cases. After emergence bird grazing was the major cause of death, preferentially of the seedlings which emerged first and had the greatest yield potential.

Because losses occurred at every stage and from many causes the solution to the problem of poor establishment requires a multidisciplinary approach.
A survey of seedling establishment in sugar‐beet crops in 1980 and 1981
Authors: DURRANT M. J.
Published: February 2008

One hundred and twenty five crops distributed throughout the UK sugar‐beet growing area were examined to identify the growth stage at which failures occurred during the seedling establishment phase. Establishment varied between 15 and 90% and averaged 64 and 67% in 1980 and 1981 respectively. It exceeded 70% in 46% of fields.

Overall, the actual seed spacing was only 0·15cm wider than the 17·0cm intended but the number of seed stations in individual fields varied from 27% less to 19% more than the target. On average the drill failed to place a seed at 5% of seed stations but up to 14% misses were recorded. Germination in the field was 92% ‐ only 1% less than in the standard laboratory germination test. However, on average, 16% (range 2 ‐ 42%) of seeds which germinated failed to develop much further; the cause of only a quarter of these losses was identified as due to soil pests, diseases or being caught under stones or clods. There was a tendency for more seeds to fail between germination and emergence as the proportion of empty seed stations increased.

Rapid emergence usually resulted in greater final emergence. There were post‐emergence losses in 122 of the 125 fields. These losses averaged 6% and exceeded 14% on five fields. Birds were considered to have killed plants in 49 fields, soil pests caused losses in 20 fields and herbicides, fungal disease or grazing by rabbits or hares decreased plant stands in about 10 fields.
The relationship between leaf canopy development and yield of barley
Authors: RUSSELL G. , ELLIS R. P.
Published: February 2008

A study was carried out into the relationship between sowing date, canopy development and yield of four barley genotypes sown in autumn and spring. Yield was considered as the product of PAR absorbed by the crop canopy up till anthesis, the dry matter: radiation quotient, the ratio of grains m2at maturity to the weight of the crop at anthesis and the mean grain weight.

Equations were derived to predict the time course of the proportion of PAR absorbed in relation to date of sowing using thermal time as predictor. In crops that were not short of water and were fully vernalised, genotypic differences were detected in plant population density, date of anthesis, and the four yield components identified above. All attributes except plant population density were affected by shortage of water but genotypes differed in their response.
A comparison of Brussels sprout seedling establishment from ungerminated and low‐moisture‐content germinated seeds
Authors: FINCH‐SAVAGE W. E.
Published: February 2008

The moisture content of newly‐germinated Brussels sprout seeds (radicles 1 ± 0·5 mm long) was reduced to 16% without loss of viability when compared with untreated newly‐germinated seeds. Seedling emergence and growth from these low‐moisture‐content germinated (LMCG) seeds and ungerminated seeds were compared in cellular trays and seedbeds. A greater number of seedlings emerged more uniformly and more rapidly from LMCG seeds than from ungerminated dry seeds, leading to larger, more uniform seedlings for subsequent transplanting.

Post‐germination separation in sucrose solutions before drying resulted in a seed batch with 98% of germinated seeds. As there was a positive relationship between the rate of germination and subsequent seedling growth, it is suggested that germinated‐seed separation techniques could be used to select the most vigorous seedlings.
Further studies on double‐stranded RNA species from raspberry plants infected with aphid‐borne viruses
Authors: JONES A. T. , MITCHELL M. J.
Published: February 2008

Analysis by electrophoresis in polyacrylamide gels, followed by silver staining, of dsRNA extracted from many samples of raspberry leaves infected with raspberry leaf mottle virus (RLMV) and/or raspberry leaf spot virus (RLSV) failed to detect reliably any significant quantities of dsRNA species in excess of 1·0 × 106mol. wt. This contrasts with results reported from Canada where three dsRNA species of estimated mol. wt 2·6 × 1061·6 × 106and 1·1 × 106were consistently associated with infection with RLSV but none were associated with RLMV. However, in Scotland, four dsRNA species of estimated mol. wt 2·4 × 1061·6 × 1060·7 × 106and 0·3 × 106were detected in raspberry infected with apple mosaic ilarvirus. These results suggest that the dsRNA species reported from Canada are not those of RLSV but are probably those of a second virus, possibly an ilarvirus, which occurs together with RLSV and/or induces similar symptoms. A few samples from plants infected with RLMV and RLSV contained very small amounts of two dsRNA species of estimated mol. wt 4·7 × 106and 4·5 × 106. It is not known whether these species are those of RLMV and RLSV.
A marking device for the identification and measurement of growth zones in seedlings with minimum mechanical stress1
Authors: JONES RUSSELL S. , MITCHELL CARY A.
Published: February 2008

A device was designed to mark the growth zones of elongating seedling stems rapidly and accurately without exposing the tissue to mechanical stress. The device consists of a spring‐loaded clamp, two plastic, grooved holders attached to either side of the open end of the clamp, a narrow foam pad to cushion and support the plant tissue, and a narrow nylon marking head. The marking head contains flat‐topped ridges, 0·5 mm in width, machined such that the ridges are 2 mm (± 0·1) apart. Marking is accomplished using India ink. The procedure is rapid, precise, relatively inexpensive to build and operate, and does not require sophisticated or expensive instrumentation to obtain meaningful data. With practice, up to 100 seedlings may be uniformly marked in one hour. Tests using dark‐grown soybean (Glycine max), sunflower (Helianthus annuus), and pea (Pisum sativum) show that the device does not itself cause a reduction in growth.
Wound‐induced changes in DIMBOA (2, 4 dihydroxy‐7‐methoxy‐2H‐1, 4 benzoxazin‐3(4H)‐one) concentration in maize plants caused by Sesamia nonagrioides (Lepidoptera: Noctuidae)
Authors: GUTIERREZ C. , CASTAÑERA P. , TORRES V.
Published: February 2008

Two maize (Zea mays) inbred lines, A‐619, (high DIMBOA content) and W‐117 (low DIMBOA content) were artificially infested, at similar physiological stages, with 10 first‐instar larvae of Sesamia nonagrioides. The DIMBOA concentration in stem and leaf tissues of damaged and undamaged plants was measured quantitatively in response to larval attack. After 60 h of infestation, both inbred lines were found to respond to insect attack by increasing significantly (P< 0·01) the DIMBOA content in leaf tissues compared with uninfested controls. Similar results were observed 5 days after infestation. No significant differences were found between the stem tissues of the two cultivars during this period. After 9 days infestation, significant increases (P <0·01) could still be found in the stem tissues of the two lines, these showing signs of wounding due to direct insect damage. Thereafter, until day 25 following infestation (the last day of measurement) no significant increased level of DIMBOA was recorded in stem and leaves of the infested lines in any sampling. The production of this compound appears to be a physiological response of the plant to attack induced by physical disruption of its tissues.
Integrated control of potato cyst nematodes using small amounts of nematicide and potatoes with partial resistance
Authors: ALPHEY T. J. W. , PHILLIPS M. S. , TRUDGILL D. L.
Published: February 2008

The control of potato cyst nematode (PCN) by less than approved amounts of nematicide combined with partially resistant potato clones was studied in a series of field experiments. On a site heavily infested with Globodera pallida only the most resistant clone (12380ac2) decreased the population density in untreated soil. With aldicarb at its full approved rate (3·36 kg ha‐1) numbers of PCN were decreased under all the genotypes, including the non‐resistant Maris Piper. Aldicarb at 1·68 kg ha‐1significantly decreased populations on all clones except 12380ac2. Aldicarb at 0·84 kg ha‐1still significantly decreased population densities and multiplication rates of G. pallida on two clones with intermediate resistance (12243acl and 11233ab22). At two G. rostochiensis sites with light infestations nematode multiplication rates were greater and the control given by aldicarb and partially resistant genotypes of potato was not as great as that at the site with G. pallida.

Tuber yields were not increased by the application of aldicarb at the G. rostochiensis infested sites. However, at the site heavily infested with G. pallida the yield of the most intolerant genotype (12380ac2) was increased seven‐fold by the full rate of aldicarb (3·36 kg ha‐1) and four‐fold by the quarter rate (0·84 kg ha‐1)‐Yield of the most tolerant genotype (12243acl) was unaffected by the application of aldicarb.
The size distribution of potato tubers and its application to grading schemes
Authors: GLASBEY C. A. , McRAE D. C. , FLEMING J.
Published: February 2008

The weight, length, breadth and depth were measured for each of 10 000 potato tubers. These were samples over 3 years of the 10 most commonly grown UK maincrop varieties. Volume, square‐mesh riddle size and average projected area were also measured in the final 2 years. A multivariate log‐normal distribution was found to give a good fit to the data. Illustrations are presented of how this distribution can be used to assess grading schemes.
Involvement of ethylene in the disease caused by Botrytis cinerea on rose and carnation flowers and the possibility of control*
Authors: ELAD YIGAL
Published: February 2008

Ethylene production by flowers, petals and leaves of rose was correlated with severity of grey mould. However, when the host became completely macerated, ethylene production diminished. Ethylene production by Botrytis cinerea grown on autoclaved flowers which were supplemented with methionine was negligible. Methionine spray, incubation with ethylene, or precooling of flowers at 4°C increased disease incidence considerably. Ethylene also induced susceptibility of carnation flowers to attack by B. cinerea. On the other hand, sprays of silver thiosulphate (STS) aminooxyacetic acid (AOA) and aminoethoxyvinylglycine (AVG) decreased disease severity in rose petals and leaves inoculated with mycelial plugs or conidia. Treatment of cut rose flowers with STS (by dipping) or AOA (by spraying) significantly decreased disease incidence during subsequent incubation at 20 and 10°C. This suggests a treatment for reducing grey mould damage in flowers transported overseas.
A single wheatgrass chromosome reduces the concentration of barley yellow dwarf virus in wheat
Authors: BRETTELL R. I. S. , BANKS P. M. , CAUDERON Y. , CHEN X. , CHENG Z. M. , LARKIN P. J. , WATERHOUSE P. M.
Published: February 2008

Seedlings of a series of addition or substitution lines of wheat containing different Thinopyrum intermedium chromosomes were inoculated with the PAV and RPV serotypes of barley yellow dwarf virus (BYDV). Reduced virus titres in infected plants were ascribed to a single pair of homoeologous group 7 chromosomes from Th. intermedium in the disomic addition lines L1 and TAF 2. The group 7 chromosome is associated with red pigmentation of coleoptiles, which was also observed in two lines ditelosomic for the α arm of the chromosome. However, when infected with the PAV serotype of BYDV, the ditelosomic lines had normal virus titres and it is concluded that potential determinants of BYDV resistance are located on the β arm of the Group 7 chromosome.
Factors affecting orchard colonisation by the black‐kneed capsid (Blepharidopterus angulatus (Hemiptera:Miridae)) from alder windbreaks
Authors: GANGE A. C. , LLEWELLYN M.
Published: February 2008

The colonisation of orchards by Blepharidopterus angulatus (the black‐kneed capsid bug) from alder windbreaks was investigated, to determine its use as a biological control agent of orchard pests. The aphid Pterocallis alni provides an abundant and acceptable food for the capsid on alder. The key capsid mortality factor on windbreaks was the loss of adult females through migration. Clipping the windbreak prior to the aphid population peak resulted in male capsids migrating and females remaining, while clipping after the aphid population peak resulted in both sexes migrating to nearby orchards. Guidelines are given for windbreak management as part of a system of integrated orchard pest control.
Environmental constraints on the efficiency of selection for malting quality in barley
Authors: ELLIS R. P. , SWANSTON J. S. , TAYLOR K. , BRUCE FRANCES M.
Published: February 2008

A range of screening tests has been applied to samples of barley from breeders' trials to evaluate the usefulness of rapid tests. The prediction of the malting potential of genotypes over seasons was best achieved by the use of hot water extract measurements. Environmental effects can result in a poor relationship between hot water extract and grain characters such as β‐glucan content and thousand corn weight. Hot water extract varied considerably over sites, but results relative to a control cultivar were consistent provided that trials in which material malted poorly were eliminated from the comparisons.
Predicting spring oviposition by raspberry cane midge from accumulated derived soil temperatures
Authors: GORDON S. C. , BARRIE I. A. , WOODFORD J. A. T.
Published: February 2008

An accumulated soil temperature model is described which calculates the first oviposition date for overwintered populations of the raspberry cane midge (Resseliella theobaldi). The model uses values for mean 10 cm soil temperature, derived from daily maximum and minimum air temperatures and 10 cm soil temperature at 0900 GMT. It was developed by minimising the variation between observed dates for the start of oviposition over an 8‐yr period and accumulated air or soil temperature, using a series of base temperatures. The best fit was obtained with soil temperatures accumulated above a base temperature of 4°C. Oviposition was predicted to start when the daily accumulated soil temperature reached 339°C days above a base temperature of 4°C.

Field observations and model predictions suggested that emergence and oviposition dates were influenced by the direction of the slope of raspberry plantations. To compensate for this, an empirical correction has been incorporated into the model to advance or retard the predicted oviposition date by adjusting the estimated maximum soil temperature to allow for aspect. The geographical variation between dates for first oviposition was simulated by running the model for nine meteorological sites in the UK in 1985 and 1986.
Cereal aphids and the infectivity index for barley yellow dwarf virus (BYDV) in northern England
Authors: McGRATH P. F. , BALE J. S.
Published: February 2008

Suction traps at Leeds University Farm, N. Yorkshire, monitored aerial populations of cereal aphids over three autumns. Different migration patterns were observed between the four main species, Sitobion avenae, Metopolophium dirhodum, Rhopalosiphum padi and R. insertum. The relevance of these patterns to the epidemiology of barley yellow dwarf virus (BYDV) is discussed.

Transmission tests revealed S. avenae to be the major vector of BYDV, rather than R. padi, which is responsible for disease outbreaks in the south and west of Britain. An Infectivity Index (II) of 50 has been advocated for R. padi‐transmitted BYDV, above which economic damage is likely to occur. This value is shown not to be applicable to the Vale of York, and methods of adapting the data are proposed. Such adjusted II values depend on the behaviour and reproduction of the aphids during the transmission tests, and produce II values that correlate well with levels of field infection in the area.
Climatic factors influencing spore production in Alternaria brassicae and Alternaria brassicicola
Authors: HUMPHERSON‐JONES F. M. , PHELPS KATHLEEN
Published: February 2008

Sporulation in A. brassicae and A. brassicicola on naturally‐infected leaf discs of oilseed rape and cabbage required humidities equal to or higher than 91.5% and 87% r.h. respectively. The optimum temperatures for sporulation were 18–24°C for A. brassicae and 20–30°C for A. brassicicola at which temperatures both fungi produced spores in 12–14 h. Above 24°C sporulation in A. brassicae was inhibited. At sub‐optimal temperatures sporulation times for A. brassicicola were significantly longer than for A. brassicae with the differences increasing with decrease in temperature. Interrupting a 16‐h wet period at 20°C with a period of 2 h at 70% or 80% r.h. did not affect sporulation in either fungus but a dry interruption of 3–4 h inhibited sporulation in both. Exposure of both fungi to alternating wet (18 h at 100% r.h., 20°C) and dry periods (6 or 30 h at 5565% r.h., 20°C) did not affect the concentration of spores produced in each wet period. Sporulation times were not affected by either the host type of the age of the host tissue. White light (136 W/m2) inhibited sporulation in A. brassicae with the degree of inhibition increasing with increasing light intensity. The effect of light on sporulation in A. brassicicola was not tested.
Yield and persistency of contrasting white clover populations grown in pure swards and in mixed swards with S.23 perennial ryegrass
Authors: EAGLES C. F. , OTHMAN O. B.
Published: February 2008

Ten contrasting white clover populations were grown as spaced plants, in pure clover swards and in mixed swards with S.23 perennial ryegrass. Four of the populations were also tested for tolerance of low temperatures.

In the establishment year, the autumn yields of populations were correlated with leaf size. However, during the severe winter which followed, populations with large leaves, particularly those of Mediterranean origin, suffered extensive stolon kill. This winter damage reduced the spring yields and total annual yields of populations with large leaves, so that leaf size and total annual yield were not correlated in the year after sowing.

Stolon kill was positively correlated with autumn growth activity as measured by leaflet size and stolon internode length in October. Stolon kill during winter was correlated with cold tolerance of naturally‐hardened stolon apices, assessed in artificial cold tests.
The lack of enzymic browning in the wild potato species Solanum hjertingii compared with commercial Solanum tuberosum varieties
Authors: GUBB I. R. , HUGHES J. C. , JACKSON M. T. , CALLOW J. A.
Published: February 2008

Enzymic browning of tuber tissue was evaluated quantitatively for 50 genotypes, representing seven accessions, of Solanum hjertingii, a wild potato species from north‐east Mexico, together with five commercial varieties of Solanum tuberosum with a known range of enzymic browning.

Ninety‐four percent of S. hjertingii clones examined showed less browning than the commercial varieties, with 66% exhibiting half the ‘potential browning’ (a measure of the total enzymic browning resulting from disruption of cellular compartmentalisation in that system) of cv. Maris Piper, a low enzymic browning cultivar. Of these clones, 18 showed no visual discoloration when sliced. Results clearly indicate that the lack of enzymic browning in S. hjertingii is a ‘true’ character.

The efficiency of one subjective and two objective methods for obtaining different measures of enzymic browning was assessed. Potential browning of a rehydrated freeze‐dried powder was adopted as the most efficient technique for screening enzymic browning.
Effects of plant growth regulators on tiller bud outgrowth in uniculm cereals
Authors: WOODWARD E. J. , MARSHALL C.
Published: February 2008

Plant growth regulators were applied either to seeds or to leaves of uniculm selections of barley and wheat. None of the treatments stimulated the growth and development of tiller buds in the barley selection. In contrast, in wheat the development of tiller buds was readily stimulated and tillers were produced following treatment with Terpal, Cerone, TIBA or nitrate. In Terpal and Cerone treated plants, the stimulation of tiller bud outgrowth and tillering was accompanied by a marked retardation of growth in the main shoot. The growth of the tillers was however not sustained in any of the treatments, and so at maturity all plants were virtually uniculm. The results are discussed in relation to the different overall response of the two species, the death of tillers, and the hormonal regulation of tiller bud development.
Salt tolerance of Agaricus bisporus in relation to water stress and toxicity of sodium ions
Authors: AWAD A. S. , NAIR N. G.
Published: February 2008

Using NaCl or polyethylene glycol (PEG) solutions to progressively decrease the external osmotic potential of the peat casing of the growing medium used to culture the mushroom Agaricus bisporus resulted in proportionately decreased yields of sporophores. Over the range of ‐0.07 to ‐0.37 MPa, the extent of decrease in yield was similar with both types of osmoticum. However, with further decrease in external osmotic potential (from ‐0.37 to ‐0.62 MPa) there was a further proportional decrease in sporophore yield with PEG but a complete suppression of sporophore production with NaCl. Treatments with both NaCl and PEG decreased the concentrations of P, Mg, K, Fe and Mn, but not N and Cu, in sporophore dry matter. Treatment with NaCl solutions increased the concentrations of Na and CI ions in sporophore dry matter and decreased the concentration of Ca; PEG solutions had no effect. Ion toxicity associated with excessive accumulation of Na and C1 ions, or ionic imbalance associated with the concomittant decrease in Ca ions appear to be additional factors to osmotic stress in decreasing yield of sporophores when the growing medium becomes highly saline. The critical concentration of NaCl which caused 10% reduction in sporophore yield was 28 mM; A. bisporus is, therefore, moderately salt‐sensitive.
The spread of apple brown rot (Monilinia fructigena) by insects
Authors: LACK K. J.
Published: February 2008

Field and laboratory experiments were carried out to compare the spread of apple brown rot (Monilinia fructigena) by free aerial transmission of conidia, with insect spread of the pathogen. Significantly more brown rot developed on injured apples which had been visited by insects than on unvisited ones. The results obtained suggest that insects play an important role in aetiology of the disease, especially under conditions unsuitable for abiotic spread.