bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and practice of a glasshouse screening technique for resistance of wheat to the aphid Sitobion avenae
Authors: LOWE H. J. B. 
Published: February 2008

SUMMARYDifferences in resistance to S. avenae were confirmed amongst eight spring wheat stocks in glasshouse tests. Taking these stocks as standards, a glasshouse screening technique was developed in which 15 plants of each entry were arranged randomly in one block and aphids were scattered over the whole at the stem‐extension phase. When the infestation of individual plants was scored about 2 wk later, resistant and susceptible stocks were well differentiated. Provided that scoring was completed before or at ear emergence, separation of resistant entries was more efficient with older plants. Ranking of the standard stocks was little influenced by other variations of technique or environment.Twenty‐six out of 91 previously untested spring wheat breeding lines appeared to be moderately resistant to S. avenae, suggesting that progress in the selection of resistant cultivars will depend more on the further development of suitable techniques than on the availability of heritable resistance.
Resistance to halo‐blight in the Cambridge accessions V4604 and V4058 of Phaseolus beans
Authors: INNES N. L. , CONWAY JANET , TAYLOR J. D. 
Published: February 2008

SUMMARYV4604, a Cambridge University accession of Phaseolus vulgaris, had a high degree of leaf resistance to race 1 of Pseudomonas phaseolicola and partial resistance to race 2. Genetic control of resistance to race 1 was by a major dominant gene which is also present in the cv. Red Mexican. The partial resistance of V4604 to race 2 was under polygenic control, as was the low level resistance to race 2 in V4058.
A method for assessing the field susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica)
Authors: LAPWOOD D. H. , GANS P. T. 
Published: February 2008

SUMMARYIn experiments to develop a method for assessing the field susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica) seed tubers were stab‐inoculated near the stolon (attachment end), with a suspension of the bacterium, or with water, before planting. Disease symptoms were recorded in three years (1980–1982) and plant growth and yield in 1982. Estima and Maris Bard were the most susceptible cultivars with many plants failing to emerge and most of those that did showing disease symptoms. Pentland Crown was the most resistant: few plants failed to emerge and few showed blackleg. Nevertheless compared with water‐inoculated plants bacterial inoculation of the seed tubers of this cultivar caused loss of yield and differences in tuber size distribution. Cara, Wilja and King Edward showed intermediate reactions.
Genetics of resistance to bacterial speck of tomato caused by Pseudomonas syringae pv. tomato
Authors: FALLIK E. , BASHAN Y. , OKON Y. , KEDAR N. 
Published: February 2008

SUMMARYTwo tomato cultivars, Ontario 7710 and Rehovot 13, and their F1, F2, F3 and backcross progenies were screened for resistance to bacterial speck (Pseudomonas syringae pv. tomato) of tomato. The results support the hypothesis that the resistance factors contained in the two parents are non‐allelic and controlled by two different genes.
Patterns of aphid resistance in the genus Vicia
Authors: BIRCH N. , WRATTEN S. D. 
Published: February 2008

SUMMARYThe performance of three aphid species, Aphis fubae, Acyrthosiphon pisum and Megoura viciae, was quantified on 22 taxonomically‐selected host plant species from the genus Vicia (vetches), using intrinsic rate of increase (rm) k standard errors. A. pisum proved to be the most successful aphid species, both in terms of highest potential population increase and widest host range; M. viciae was least successful, with most restricted host range and low rm values on all but the closest relatives of Vicia faba. A wide range of antibiotic resistance was found within the genus, and host resistance to the three aphid species was found to be broadly related to classification patterns based on taxonomy and life‐form. Analysis of the components of rm revealed that nymphal survival rates were the most significant factor limiting host colonisation, not pre‐reproductive period which is the most important factor in cultivars of V. faba. The consequences of aphid polyphagy on performance are discussed.
Aspects of nitrogen uptake and distribution in maize
Authors: ALLISON J. C. S. 
Published: February 2008

SUMMARYThe amount of nitrogen (N) taken up after treatment decreased by nearly 50% when either the top five or middle four leaf laminae of maize (Zea mays) plants were removed shortly after flowering, and by 70% when both the middle four and bottom six laminae were removed, but the amount of N moving from the remaining parts of the shoot to the grain did not change much. When all the laminae were removed little N was taken up and only 35% as much N as in untreated plants moved from the shoot to the grain. Removal of all the laminae increased the N content per cent of dry weight of both grain and shoot at final harvest, but the other treatments did not have much effect on the N concentration of any of the parts of the shoot.Plants bearing grain, whether intact or with alternate laminae removed (half‐defoliated) at the time of flowering, took up N approximately in proportion to their increase in dry weight during the 4 wk after flowering. The N taken up went to the ear (husks, core and grain) and so did N from the stem and leaves. Intact and half‐defoliated plants with no developing grains, because pollination had been prevented, took up no N during this period, though they accumulated about as much dry matter as did plants with grain; the N increment of the husks and core was supplied by the stem and leaves.At final harvest total and grain N content of plants per unit area of land increased by 20 and nearly 30%, respectively, with increase in population between 2·3 and 6·1 plants/m2, but apparently fell slightly with further increase of population to 7·4 plants/m2. Until shortly after flowering N uptake was rapid enough to maintain similar N contents per cent of dry weight of the parts of the shoot in all populations. Uptake continued at a steady rate, though a slower one than before flowering, until near the time of final harvest in the most widely spaced population. In the denser populations uptake slowed down progressively after flowering, and in the densest population it apparently ceased a few weeks before final harvest. The N concentration of the grain of maturing plants fell with increase of population, but not that of the other parts of the shoot. At final harvest N content of the grain decreased from 1·6% in the most widely spaced to 1·2% in the densest population. That of the rest of the shoot varied between 0·70 and 0·79%. Between 6 and 18 wk after sowing, N content per unit area of green parts of the leaf laminae decreased only slightly, changing from about 20 to 18 mg/dm2 with 2·3 plants/m2, 18 to 16 mg/dm2 with 3·5 plants/m2, and 16 to 13 mg/dm2 in populations between 4·8‐7·4 plants/m2.
Visual assessment of grain yield and its components in single plants and ears of spring barley
Authors: ISMAIL A. B. , VALENTINE J. 
Published: February 2008

SUMMARYVisual assessments of yield/plant and tillers/plant were more effective than unaided assessments of grains/ear and 1000‐grain weight on a per plant basis. Assessments of the latter yield components were generally improved by the use of specially developed keys described by Ismail & Valentine (1983). Gains in efficiency were associated with the amount of extra time spent on making these assessments.Assessments of yield/ear were not more effective than assessments of yield/plant. This was attributed to the ease of assessment of tillers/plant which was strongly associated with yield/plant. Assessments of grains/ear and 1000‐grain weight in single ears were clearly more effective than corresponding assessments in single plants in which there is high variability between ears.Apart from using keys, further improvements in the assessments of grains/ear and 1000‐grain weight are necessary in order to increase the effectiveness of single plant selection in the F2 generation which is the first opportunity of increasing yield in later generations.
Viability of onion (Allium cega) seed as influenced by temperature during seed growth
Authors: GRAY D. , STECKEL JOYCE R. A. 
Published: February 2008

SUMMARYThe yield and performance of seeds from crops of winter‐hardy, bolting‐resistant onion grown at temperatures of 15–16, 18–19 and 22–23°C in 1979, 1980 and 1982 were compared.Yields of seed from crops grown at 22–23°C were lower than those from crops grown at lower temperatures but the seeds ripened between 11 and 32 days earlier. Seeds from crops grown at mean temperatures of above 18°C gave higher percentage germination when imbibed at 30°C than 20°C and they also gave higher percentage seedling emergence than those from crops grown at lower temperatures. Seedlings from seeds produced at mean temperatures above 18°C were heavier than those from seeds of a similar weight but produced at lower temperatures. None of these differences were associated with differences in seed weight, embryo weight or seed dormancy but were positively correlated with differences in seed N‐concentration. The differences were also associated with the rate of imbibition of water as high germination, high N‐content seeds had a slower rate of imbibition than low germination, low N‐content seeds of the same weight.
The effects of growth stage in wheat on yield reductions caused by the rose‐grain aphid Metopolophium dirhodum
Authors: WATT A. D. , WRATTEN S. D. 
Published: February 2008

SUMMARYField‐caged populations of the rose‐grain aphid Metopolophium dirhodum were established on winter wheat (cv. Bounty) during the summer of 1981. An early wheat growth stage (G.s.) (40 to 69) and a late (G.s. 65 to 73) aphid infestation treatment were compared; only the early infestation resulted in a significant reduction in grain weight (15%), although the infestation sizes were similar in the two treatments. Baking quality of the flour was unaffected by both treatments. Caged populations were also established on winter wheat (cv. Avalon) in 1982 but, in spite of aphid numbers as large as in 1981, no significant yield loss was recorded. An infection of take‐all fungus Gaeumannomyces graminis developed during the course of this experiment and may have masked the effect of the aphids.
Glasshouse tests and field selection for heritable resistance to Myzus persicae in sugar beet
Authors: LOWE H. J. B. , SINGH MOHAN 
Published: February 2008

SUMMARYA technique is described to assess and select in the field for resistance to Myzus persicae in sugar beet. Lines developed by this method were aphid resistant when compared with commercial cultivars. The resistance was inherited by progeny lines. Variation between beet lines in glasshouse tests suggested segregation of a number of resistance genes with varying effects. Integration of selection for aphid‐resistance and agronomic performance during beet breeding is discussed.
The effect of growth retardant application on floret site utilisation and assimilate distribution in ears of perennial ryegrass cv. S.24
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D. 
Published: February 2008

SUMMARYApplication of the growth retardant paclobutrazol (PP333), at 2 kg a.i. ha‐1 at spikelet initiation to plots of perennial ryegrass cv. S.24 in 1981 and 1982 significantly increased the number of seeds per spikelet present at final harvest by reducing the number of seeds aborted during seed development. Distribution of florets and seeds per spikelet was altered by PP333, as both basal and penultimate spikelets contained more florets and seeds than did those of untreated plants. Seed weight and germination were increased in florets of penultimate spikelets, although PP333 application delayed maturity by 3–5 days.In untreated plants, assimilate recovery was significantly lower from the terminal section of the ear, whereas in PP333 treated plants, no differences were found between basal, intermediate or terminal sections of the ear. PP333 increased assimilate demand at all sections of the ear when the ear and leaves were fed. The implications of this are discussed.
Restricted multiplication of potato leafroll virus in resistant potato genotypes
Authors: BARKER H. , HARRISON B. D. 
Published: February 2008

SUMMARYPlants of a range of potato genotypes differing in rating for field resistance to potato leafroll virus (PLRV) were inoculated with the virus by grafting or by aphids (Myzus persicae). Plants of all genotypes tested became infected by each inoculation method and PLRV was detected by ELISA in the upper leaves of all genotypes within 26 days after grafting. Most genotypes with high resistance ratings developed only mild primary and secondary symptoms whereas those with low resistance ratings developed more pronounced symptoms. However, one genotype (G7461(4)) with a high resistance rating was very severely affected. The concentrations attained by PLRV in genotypes with high resistance ratings were only 1–10% of those in genotypes with low resistance ratings. These differences in virus concentration were found in young leaves of plants with primary or secondary infection, whether inoculated by grafting or by aphids and whether grown in the glasshouse or the field. In older leaves, differences in virus concentration between genotypes were at least as pronounced as those in younger leaves. In contrast, PLRV concentration in vascular tissue at the heel end of tubers of plants with primary infection was similar for all the genotypes tested. Although low PLRV concentration was consistently associated with high resistance rating it is not the only form of resistance to PLRV occurring in potato.
Pre‐harvest retting of flax with glyphosate: effect of growth stage at application on uptake, translocation and efficacy of glyphosate
Authors: HARVEY B. M. R. , SPENCE L. , CROTHERS S. H. 
Published: February 2008

SUMMARYFlax cv. Hera was grown in pots at a density of 2000 plants/m2. At various stages of maturity plants were either sprayed with glyphosate (Roundup, Monsanto plc) at a rate equivalent to 1.4 kg a.e./ha or the uppermost leaves of the main stem were treated with 14C‐glyphosate. Uniform desiccation to greater than 80% DM within 5 wk was obtained with sprays applied up to and at 2 wk after the mid‐point of flowering (MP) and also at 10 wk after MP, when all seed had been shed. Sprays at 4–6 wk after MP caused little or no desiccation of the lower stem.Autoradiography demonstrated that 14C‐glyphosate applied to the 10 uppermost leaves of the main stem at MP, or to the upper stem at 10 wk after MP, was distributed throughout the plant within 48 h. However, no downward translocation was detected within 48 h of applications during seed filling, i.e. at 2 or 5 wk after MP.Quantitative determinations of distribution of 14C‐glyphosate were made at 48 h after application either to the five uppermost leaves on the main stem or, after leaf drop, to the base of the inflorescence. Translocation out of the treated zone was 58–67% of applied 14C‐glyphosate with applications at 0, 2 or 6 wk after MP but only 13% with application to senescing leaves at 4 wk after MP. Little downward translocation occurred with any of these applications, 14C‐glyphosate accumulating mainly in the upper stem and inflorescence.Thus failure of glyphosate to desiccate the lower stem may be related to poor downward translocation during seed development and to reduced uptake into, and export out of, senescing leaves.
A preliminary comparison of some management options for reducing grass losses caused by leatherjackets in Northern Ireland
Authors: BLACKSHAW R. P. 
Published: February 2008

SUMMARYLeatherjackets can cause serious yield reductions in Northern Ireland grass. This paper considers the distribution of field population sizes derived from 19 years' data in conjuction with calculated damage functions to estimate average expected losses. Six management options were compared. These were ‘No action’, routine insecticide application in September or March, insecticide application in March in high risk years only and the use of monitoring and economic thresholds in September or March. The annual expected revenues for each of these options was calculated for herbage dry‐matter values of £0.01–0.07 kg‐1. It was concluded that action against leatherjackets in September would give better returns than action in March and that the use of monitoring and spraying of only those field populations above an economic threshold gave rise to greatest revenue. An annual loss to leatherjackets in Northern Ireland of over £15 million was calculated from an assumed herbage value of £0.035 kg‐1 dry matter.
Solar radiation interception by leafless, semi‐leafless and leafed peas (Pisum sativum) under contrasting field conditions
Authors: HEATH M. C. , HEBBLETHWAITE P. D. 
Published: February 2008

SUMMARYFoliage composition, photosynthetic area index (PAI) and radiation interception were measured for crop canopies of leafless (var. Filby), semi‐leafless (var. BS3) and leafed (var. Birte) peas (Pisum sativum). Tendrils and petioles contributed more than 60% of total leaf area for leafless peas but less than 30% for semileafless and leafed pea canopies.PAI was related to radiation interception by calculating attenuation coefficients which indicated that leafless peas intercepted more radiation per unit PAI than either semi‐leafless or leafed peas. Data interpretation, however, was complicated because of difficulties in estimating the tendril and petiole surface area contribution to PAI.Radiation interception was related to dry matter accumulation by calculating photosynthetic efficiencies. Leafless and semi‐leafless peas converted intercepted radiation into dry matter as efficiently as leafed peas.Under conditions of moisture stress, leafed and leafless peas both intercepted radiation more effectively but converted it into dry matter with reduced photosynthetic efficiency.
Photosynthesis and assimilate transport in potato with top‐roll disorder caused by the aphid Macrosiphum euphorbiae
Authors: VEEN B. W. 
Published: February 2008

SUMMARYIn pot experiments in a glasshouse, top‐roll symptoms were induced on potato plants after infestation with the aphid Macrosiphum euphorbiae. Leaves showing symptoms accumulated carbohydrates and tuber yields of affected plants were decreased by 44% compared with controls. Leaves grown after killing the aphids had a normal appearance and sugar contents. Infestation with aphids primarily inhibited carbohydrate transport in the stem and the accumulation of 14C‐labelled assimilate in the vascular bundles of the leaves. It is suggested that photosynthesis is inhibited by impaired phloem transport and subsequent accumulation of carbohydrates in the leaves and not by direct mechanical damage caused by the feeding aphid.
An analysis of leaf growth in sugar beet.
Authors: MILFORD G. F. J. , POCOCK T. O. , JAGGARD K. W. , BISCOE P. V. , ARMSTRONG M. J. , LAST P. J. , GOODMAN P. J. 
Published: February 2008

SUMMARYThe increase of leaf area index (L) was examined in a series of sugar‐beet crops grown on different sites (Broom's Barn, Suffolk and Trefloyne, Dyfed) or with different husbandry treatments (sowing dates and nitrogen rates) between 1978 and 1982. The development of L could be described as a function of thermal time using three parameters; DE, which was essentially an estimate of the thermal time required for crop establishment, and rHL and DL, the thermal rate and duration, respectively, of the increase of L. Variations in DE between seasons and with sowing date were small, but significant; they were attributed to factors affecting the condition of the seedbed. There were much larger variations in rHL, especially between seasons, sites and crops given different rates of nitrogen fertiliser, and there was a strong negative relationship between rHL and DL. Much of the variation in rHL was associated with differences in the concentrations of nitrogen in the lamina dry matter. Faster rates for rHL at Trefloyne than at Broom's Barn, and in the crop grown in 1982 as compared with other years, were also partly attributable to particularly warm conditions during the early development of some of the larger, faster‐growing leaves within the canopy. The wider application of the relationships established from these experiments was tested with data from a series of crops grown on other sites between 1960 and 1962. The relationships held particularly well for beet grown on soils with high water‐holding capacity but not for those on soils of low water‐holding capacity.
Stem‐boring Diptera in perennial ryegrass in relation to fertiliser.
Authors: MOORE D. , CLEMENTS R. O. 
Published: February 2008

SUMMARYTwo levels of fertiliser were applied to perennial ryegrass in four equal doses according to two different time schedules. Stem‐borer larvae were more frequent in plots treated with the higher rate and the relative incidence of the species varied according to fertiliser level. At the high fertiliser level the later applications resulted in an earlier increase in larval numbers and a higher larval population in the winter. At the low fertiliser level the total number of larvae was greater in the plots receiving earlier fertiliser applications due to an increase in the number of Oscinella vastator larvae. Populations of larvae were related to the tillering of the grass but not to the nitrogen content of the host plants.
The effects of post‐inoculation wet and dry periods, and inoculum concentration, on lesion numbers of Septoria nodorum in spring wheat seedlings
Authors: JEGER M. J. , GRIFFITHS ELLIS , JONES D. GARETH. 
Published: February 2008

SUMMARYLesion numbers in seedlings of spring wheat cvs Kolibri and Maris Butler, inoculated with Septoria nodorum in a growth cabinet, varied with the length of wet or dry period following inoculation. Increasing the length of dry period led to a curvilinear decrease in lesion numbers at 15° C (60% r.h.) and 20° C (40% r.h.), but some infection still occurred with a dry period of 72 h. Increasing the length of wet period gave a linear increase in lesion numbers in cv. Maris Butler, but lesion numbers levelled off at 12 h at 15° C (60% r.h.) in cv. Kolibri. Increasing the inoculum concentration gave an increase in lesion numbers in both cultivars irrespective of whether wet or dry periods followed inoculation. On occasion, Kolibri and Maris Butler differed significantly in lesion numbers, but differences were not consistent between experiments, and there were interactions with the length of wet period.