bluuebunny/crossref_metadata_2025_split huggingface dataset:
The laboratory germination of crisp lettuce seeds under moisture stress
Authors: WURR D. C. E. , FELLOWS JANE R. 
Published: February 2008

SUMMARYSeeds of the crisp lettuce cultivar Pennlake were germinated using all combinations of six ‘initial’ solutions of polyethylene glycol 6000 (PEG) with osmotic potentials ranging from 0 to ‐8 bars and seven ‘secondary’ solutions of PEG with osmotic potentials ranging from 0 to ‐10 bars, to which seeds were moved after 24 or 48 h in the ‘initial’ solution. The number of seeds germinating decreased at more negative osmotic potentials of both ‘initial’ and ‘secondary’ solutions but there was an interaction between germination temperature and the osmotic potential of the ‘initial’ solution. At an ‘initial’ solution osmotic potential of 0 bars germination at 20°C exceeded that at 10°C. As the osmotic potential of the ‘initial’ solution decreased germination at 20°C decreased more than at 10°C so that at the more negative osmotic potentials germination at 10°C exceeded that at 20°C. However seeds ungerminated after 14 days germinated normally when transferred back to water, so that the average final germination was 99.5%.The results suggest that major fluctuations in soil water potential in a seedbed are unlikely to influence seed germination per se provided that a period of 24 to 48 h at 0 bars tension is available at some time. The timing of such a period relative to sowing will have a considerable effect on the time of germination and hence the time of emergence. It is concluded that factors other than the direct effect of soil moisture content on germination are involved in reducing seedling emergence under fluctuating soil moisture conditions in the field.
Photoperiodic response and heritability of the pre‐flowering interval of two red clover (Trifolium pratense) populations
Authors: BOWLEY S. R. , TAYLOR N. L. , DOUGHERTY C. T. 
Published: February 2008

SUMMARYThe reaction to 12, 14, and 16 h photoperiods of two medium‐maturing red clover (Trifolium pratense) populations (cv. Kenland and Cycle 6 of a selection for long stems) under controlled environment conditions was studied. Under both 14 and 16 h photoperiods, Kenland flowered sooner and had shorter stems, more stems per plant, and greater herbage yield per plant but had a similar number of internodes compared to the long stem Cycle 6 population.A daylength between 12 and 14 h was critical for flower initiation in both populations. The critical daylength to induce stem initiation was shorter than the daylength to induce flowering in some genotypes.From half‐sib analyses, the narrow–sense heritability of the pre‐flowering interval in Kenland ranged from 15 to 23%. The expected response to one cycle of selection (5% selection intensity) for lengthening or shortening the pre‐flower interval was 2.3 to 2.4 days at the 16 h photoperiod and 3.0 days at the 14 h photoperiod. Low correlation between pre‐flowering interval, stem length, and stem number indicated that it may be possible to change one character without affecting the other two. The need for further studies of the genetic nature of the control of flowering in red clover was indicated.
The seasonal response of Italian and hybrid ryegrasses to the control of frit fly, Oscinella frit
Authors: MOWAT D. J. , JESS S. 
Published: February 2008

SUMMARYIn years of relatively high frit fly activity the control of all generations produced increases averaging 0×44 t d.m. ha‐1 in annual yield of Italian and hybrid ryegrass. A cutting programme designed to make the sward especially vulnerable to frit fly attack did not increase the total annual effect of pesticide treatment but accentuated the periods at which damage occurred. The annual yield increase was almost entirely obtainable by controlling the second and third frit fly generations, but even one treatment for this purpose was of doubtful economic justification. The prospect of augmenting the response to control of later‐occurring pests, such as leatherjackets or eriophyid mites, by including the part of the frit fly response which is recoverable by the same treatment, was a more probable justification for pesticide usage.There was some evidence that a Westerwold and a hybrid cultivar suffered more damage than an Italian ryegrass cultivar, but pesticide treatment did not improve the persistence of any cultivar.
Influence of microclimate on Drechslera leaf spot of young coconuts: effect of desiccation on spore survival and of moisture and shade on infection and disease development
Authors: FAGAN H. J. 
Published: February 2008

SUMMARYCulture‐produced conidia of Drechslera incurvata from coconut failed to germinate on the leaves of coconut seedlings incubating under the dry conditions of a greenhouse. Viability and rate of appressorium formation of artificially‐dispersed, culture‐produced conidia fell significantly during extended incubation of inoculated seedlings in the greenhouse, when 43% of conidia germinated after 90 days incubation compared with 62% at 59 days and 90% at 24 days. Field‐produced conidia on excised leaves also lost viability upon storage in situ on the laboratory bench; germination fell from 60% at 3 months storage to 0×5% at 5 months and no germination at 6 months.Shading of seedlings in the field with saran cloth producing 30% shade or 50% shade depressed the amount of dew forming on leaves of young coconuts and significantly reduced both the number of infections from artificial inoculations and the severity of leaf spot disease developing subsequently.
The influence of cultivar and isolate on the development of gangrene (Phoma exigua var. foveata) in potato tubers
Authors: BAIN R. A. , LENNARD J. H. , WASTIE R. L. 
Published: February 2008

SUMMARYIn studies on the infection of potato cultivars with different field isolates of Phoma exigua var. foveata, cultivar × isolate interactions, although sufficiently large to influence the relative pathogenicities of isolates on different cultivars, were not substantial enough to affect cultivar ranking order. Cultivar rank was markedly influenced by pathogen isolate only when both field and culture collection isolates were compared. This suggests that the complications of cultivar × isolate interactions can be avoided in cultivar screening tests by the use of recent field isolates of high pathogenicity. It was found that cultivar was considerably more important than isolate in determining gangrene lesion size. The need to consider both lesion diameter and depth when estimating rot size following point inoculation of different cultivars was confirmed.
The acquisition of a caulimovirus by different aphid species: comparison with a potyvirus
Authors: MARKHAM P. G. , PINNER M. S. , RACCAH B. , HULL R. 
Published: February 2008

SUMMARYThe acquisition and transmission of cauliflower mosaic virus (CaMV) by six aphid species and three clones of aphids was studied and compared with that of turnip mosaic virus (TuMV) with Myzus persicae. Two clones of Aphis fabae were unable to transmit CaMV, but the other species, Acyrthosiphon pisum, Brevicoryne brassicae, Megoura viciae, M. persicae and Rhopalosiphum padi transmitted in a bior multi‐phasic manner. There was no statistical evidence of a bimodal transmission pattern. R. padi is recorded as a vector of CaMV for the first time.The transmission efficiency of CaMV varied with time of acquisition and suggested that accumulation of the virus occurred with two peaks of efficiency within the anterior region of the insect gut. The time at which these two peaks occurred varied between the species, but the basic pattern was common to all transmitting aphid species in this study. This pattern contrasted with that of TuMV. The transmission data are discussed in terms of bimodal transmission, the influence of feeding behaviour, the role of a helper protein associated with both TuMV and CaMV and the evidence for site specific attachment of CaMV.
Relationship between root respiration and seedling age in tomato cultivars infested by Meloidogyne incognita
Authors: ZACHEO GIUSEPPE , MOLINARI SERGIO 
Published: February 2008

SUMMARYMeasurements were made of respiration in the roots of tomato cultivars susceptible and resistant to Meloidogyne incognita. Nematode infestation of the susceptible cv. Roma VF caused an initial stimulation of the total respiration with an increase in the CN‐sensitivity; the effect decreased and then disappeared as the seedlings aged. In the resistant cv. Rossol nematode infestation initially caused an inhibition of total respiration and a decrease in the CN‐sensitivity; respiration and CN‐sensitivity increased with seedling age. The activity of the alternative respiration pathway (m‐chlorobenzhydroxamic acid‐sensitive) was unchanged by nematode infestation in the resistant cultivar and increased markedly in the susceptible cultivar during the early stages of infestation.
Observations on the control of potato cyst‐nematodes, Globodera rostochiensis and G. pallida in 35 English potato soils in pots by oxamyl and resistant potatoes
Authors: WHITEHEAD A. G. , FRASER JANET E. , PETERS C. G. , NICHOLS A. J. F. 
Published: February 2008

SUMMARYThe increase of 35 English field populations of potato cyst‐nematodes (Globodera rostochiensis and/or G. pallida) was measured on Désirée, Maris Piper, Caxton (A25/11), Cromwell (A27/20) and clone 11233 ab 22 in pots of sandy, silty or peaty loam soil. Désirée was susceptible to all populations tested and, as in field soils, the final population (Pf) was inversely related to the initial population of potato cyst‐nematode eggs (Pi) in the soil. Maris Piper and Cromwell were resistant to all G. rostochiensis populations, with one possible exception. Maris Piper was susceptible to all G. pallida populations. Caxton was susceptible to some and fairly resistant to other populations of G. rostochiensis, indicating the existence either of two biotypes within the one pathotype (Rol) as yet encountered in Britain, or the existence of an additional pathotype. Caxton and Cromwell were fairly resistant to G. pallida. Clone 11233 ab 22 was only moderately resistant to both species. Resistance to potato cyst‐nematode increase varied considerably, especially in Caxton (to G. rostochiensis) and in 11233 ab 22 (to both species).Oxamyl greatly reduced the increase of G. rostochiensis populations on Désirée potatoes, with the notable exception of one population but it generally had much less effect on G. pallida populations, regardless of soil type. The difference in effect on the two species may be due to a longer period of hatching in G. pallida than in G. rostochiensis and also perhaps to a second generation in G. pallida.
The effects of cutting pre‐treatments on the performance of asulam on bracken (Pteridium aquilinum)
Authors: LOWDAY J. E. , LAKHANI K. H. 
Published: February 2008

SUMMARYThe performance of asulam was assessed from a field experiment in which bracken (Pteridium aquilinum) was subjected to a variety of cutting pre‐treatments prior to spraying with the herbicide. Both cutting bracken twice in the year prior to asulam application, and spraying frond regrowth 10 wk after a single mid‐June cut, improved the performance of asulam. Summer cutting removes nutrients and dry matter from the system and reduces frond height, but increases frond density and the number of active buds on the rhizome system. The enhanced efficiency of asulam on pre‐cut plots may be due to any one of these factors, or a complex interaction between some (or all) of them. In areas of tall bracken a cutting pre‐treatment has the important practical advantage of reducing the height of the canopy, making the subsequent use of ground spraying equipment easier.
Intensity of radicle fluorescence as related to the resistance of seedlings of lettuce to the lettuce root aphid and carrot to the carrot fly
Authors: COLE ROSEMARY A. 
Published: February 2008

SUMMARYA technique is described which indicates by u.v. fluorescence the concentration of caffeoylquinic, chlorogenic and isochlorogenic acids in roots of germinating lettuce and carrot. The surface fluorescence of radicles from lettuce root aphid (Pemphigus bursarius) resistant seedlings was more intense than for susceptible seedlings, attributable to the higher concentration of isochlorogenic acid. In contrast, radicles of carrot seedlings resistant to carrot fly (Psila rosae) were less fluorescent than susceptible seedlings, corresponding to the lower concentration of chlorogenic acid in resistant seedlings. The technique is non‐destructive and has been developed to distinguish between cultivars or breeding lines potentially resistant to these insect pests.
Multiple components of the resistance of potatoes to potato leafroll virus
Authors: BARKER H. 
Published: February 2008

SUMMARYIn glasshouse experiments the ranking of potato genotypes for resistance to infection with potato leafroll virus (PLRV) using three concentrations of aphid‐borne inoculum was the same as their field resistance ratings. In field‐grown plants this resistance to infection increased in all genotypes as the plants aged but its rate of increase differed between genotypes. In tests on field‐grown plants infected by aphid‐ or graft‐inoculation, the proportion of virus‐free progeny tubers increased the later the date of inoculation but was greater in resistant than in susceptible genotypes. This trend was most pronounced in the resistant clone G7445(1), in which the virus failed to move from the foliage to the tubers of some plants infected in glasshouse tests.The spread of PLRV will thus be minimised in crops of resistant compared with susceptible genotypes for three reasons: plants have greater resistance to infection, systemic spread of virus from their foliage to tubers is less likely and, as shown previously, the low concentration of virus particles in leaf tissue makes infected plants less potent sources of inoculum for aphids.
Specific immunological response against the granulosis virus of the codling moth (Cydia pomonella) in woodmice (Apodemus sylvaticus): field observations
Authors: BAILEY M. J. , FUJITA FRANCES R. HUNTER 
Published: February 2008

SUMMARYAntibodies specific to the granulosis virus (GV) of the codling moth (Cydia pomonella) were detected by indirect ELISA in sera of woodmice (Apodemus sylvaticus) trapped in an apple orchard sprayed by tractor‐drawn mist blower with 2 × 1013 virus granules C. pomonella GV/ha. Such antibodies were absent from sera of mice trapped before virus had been applied. Virus antigens were detected by double antibody sandwich ELISA on the ground in and around the orchard and also in the faeces of woodmice inhabiting the orchard, but did not persist from one year to another. Some, but not all, of the samples containing virus antigens were found to be infective.
The feasibility of producing inbred rather than F1 hybrid cultivars in Brussels sprouts: predictions from early generations
Authors: ROGERS W. J. , KEARSEY M. J. , SMITH B. M. 
Published: February 2008

SUMMARYPredicting the performance of recombinant inbred lines derived by single seed descent (SSD) following crosses between inbred lines is most reliable for traits in which epistasis and genotype environment interaction are absent. The analysis of two field trials of Brussels sprouts indicated the presence of such effects in seven quantitative characters. These effects could be minimised by transforming the scale on which each character was measured. Predictions were made of the likely performance of the recombinant inbred lines currently being produced by SSD at the Institute of Horticultural Research, Wellesbourne, compared with that of current F1 hybrid varieties.The predictions from the first trial of F2 material were encouraging for harvest date, stem length and waste weight, but low for sprout number, quality, marketable yield and total yield. Predictions from F3 material in the second trial were good for sprout number and total yield (in addition to harvest date, stem length and waste weight as before), but still low for marketable yield and quality, with less than 0 01% of lines expected to perform better than the F1. Model fitting to variances suggested the presence of linkage disequilibrium in dispersion for waste weight, but no information could be obtained about linkage disequilibrium for the two most important characters, marketable yield and quality.The broad heritability of each character except stem length was lower than 0 5 (0 3 or lower for total yield, waste weight and quality), suggesting that advanced generation selection, as used in SSD, might be more successful than selection in the early generations.
Modification and testing of a domestic freezer for use in studies of plant growth and survival at low temperatures
Authors: HAYCOCK R. , AULD M. H. D. , OLLERENSHAW J. H. , STEWART W. S. 
Published: February 2008

SUMMARYModifications of a domestic freezer are described, which convert it to a versatile controlled environment chamber capable of maintaining temperatures between ambient and ‐ 18 °C and therefore useful in investigations both of plant growth at low positive temperatures and of survival of sub‐zero temperatures. The temperature control mechanism can provide a wide range of diurnal temperature regimes and of cooling and warming rates.Measurements in two such chambers showed air temperatures were always uniform to within ° 1 °C of set temperature except in a 6 cm band round the inside walls, where they were lower by 0°6 °C, at most; CO2 concentration was always close to 300 v.p.m.; relative humidity was usually in the range 80–90% and photon flux densities during the light period were 180 ° 10 μmol m‐2 s‐1.The uniformity of environmental conditions within each chamber was confirmed by measurements of leaf growth and plant survival of tillers of a single genotype of perennial ryegrass growing in pots of compost. These tests also confirmed the lower temperature of the 6 cm band adjacent to the chamber walls.Although temperature settings were identical, air and compost temperatures were 0°3 °C higher in one of the two chambers tested. Although this difference did not result in significant differences in plant survival, significant differences in leaf lamina extension were found between cabinets.Problems encountered in the design and testing of the chambers are discussed.
Factors affecting the production of caffeoylquinic acid levels in germinating carrot seedlings and its estimation by u.v. epifluorescence microscopy
Authors: COLE ROSEMARY A. 
Published: February 2008

SUMMARYConditions for obtaining reproducible estimates of caffeoylquinic acids in carrot seedlings, by fluorescence intensity determined using epifluorescent microscopy were investigated. The optimum germination conditions for the test were established as 9–10 days at 20 °C. Factors such as the presence of microflora on seed material and the environment of the seed during production were found to influence the mean radicle fluorescence.
Seasonal changes in the free amino acids of oat and barley phloem sap in relation to plant growth stage and growth of Rhopalosiphum padi
Authors: WEIBULL J. 
Published: February 2008

SUMMARYThe concentrations and composition of free amino acids in phloem sap from two cultivars of oats and barley, both susceptible to the aphid Rhopalosiphum padi, were determined by means of high performance liquid chromatography. Sap was collected from excised aphid stylets at three developmental stages (seedlings, tillering plants and plants undergoing stem elongation) from plants given or not given fertiliser and grown outdoors. In connection, the growth of individual R. padi nymphs was estimated at the same phenological stages on plants grown in the greenhouse.The content of free amino acids was consistently higher in seedlings than in plants at the early tillering stage. Only in seedlings did the addition of fertiliser increase amino acid levels. Barley phloem sap contained more free amino acids than that of oats when fertiliser was added and at later developmental stages.Phloem sap of oats and barley showed similar patterns in their composition of free amino acids at the seedling stage, but as the plants grew older the patterns became increasingly different. Plants given fertiliser had higher amounts of dicarboxylic amino acids (glutamic and aspartic acid) than unfertilised plants. The concentrations of γ‐amino butyric acid, glycine, histidine, and methionine were very low in all treatments.The relative growth rates of R. padi nymphs were low when amino acid content was low and vice versa. The results are discussed in relation to host plant suitability and plant resistance mechanisms.
Effect of spacing in cow pea (Vigna unguiculata) on damage by the black cowpea moth, Cydia ptychora (Lepidoptera: Tortricidae)
Authors: OFUYA T. I. 
Published: February 2008

SUMMARYThree indeterminate cowpea cultivars with different growth habits were each planted at four inter‐row spacings in two different seasons at Ile‐Ife, Nigeria, and at harvest assessed for Cydia ptychora damage. Damage by the moth increased with decreasing inter‐row spacing much more in the erect and semi‐erect cultivars, than in the semi‐prostrate cultivar.
Populations of Rhizoctonia solani in soil under crops in rotation with sugar beet
Authors: HERR LEONARD J. 
Published: February 2008

SUMMARYUsing a soil debris isolation method, populations of Rhizoctonia solani were monitored over a 4 ‐yr period in four fields which were initially cropped to sugar beet and in which four areas of Rhizoctonia crown rot diseased beets (DA) and four areas of apparently healthy beets (AH) had been selected and precisely located. Soil from these areas was assayed during the subsequent crops, which included sugar beet, tomato, cucumber, maize and soybean. No significant differences in colony counts were found between the soils in DA and AH on any of 30 sampling dates. R. solani population counts were, in general, quite low, except under sugar beet and following tomato harvest. Areas of diseased beet and high R. solani soil populations that developed in subsequent sugar beet crops did not necessarily coincide with the previously selected diseased areas. High R. solani populations developed from parasitic activity on sugar beet or saprophytically on tomato crop residues. Of the other crops, both maize and soybean may have slightly increased the low R. solani residual populations in soil. The monitoring of R. solani populations in the season prior to, and during the early season of sugar beet cropping did not provide a basis for forecasting disease in fields or sites within fields. The initiation of disease patches in these sugar beet fields was therefore governed by factors other than inoculum density.