bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of plant population on the production and distribution of dry matter in maize
Authors: ALLISON J. C. S. 
Published: February 2008

SUMMARYGrain and total dry weight of maize (Zea mays L.) at final harvest increased by about 50% and 30%, respectively, when the population was increased from 23000 to 48000 plants/ha, but did not increase further with population up to 74000/ha.Between 6 and 10 weeks after sowing, crop growth rate (C) increased by about 40% with increase in leaf‐area index (L) from 2 to 5·5, despite a concomitant increase in moisture stress. Immediately after flowering, which occurred at 10–11 weeks, C increased up to the greatest L attained, 6·7, and would probably have reached a maximum, with L about 7, when nearly all the incident light would be intercepted by foliage. Later, the L at which C was maximal decreased, probably because the photosyhthetic efficiency of leaves decreased faster with time as L increased; 18 weeks after sowing, when L varied between 3 and 5·5, C was maximal when L was 5.The proportion of grain in the dry matter accumulated after flowering increased from 73% when population was 23000/ha to 82% when it was 60000–74000/ha. Stem weight increased until 3–4 weeks after flowering, then remained constant when population was 23000/ha, but decreased in denser populations. The fraction of the ear consisting of grain increased with population.
The effects of superficial wax on leaf wettability
Authors: HOLLOWAY P. J. 
Published: February 2008

SUMMARYExperiments are described which provide more information on the role played by superficial waxes in the natural water‐repellency of leaf surfaces. Contact angles of water were measured on a variety of leaf surfaces, before and after removal of wax, and on smooth films of the isolated superficial waxes. The differences in wettability of leaf surfaces are not wholly accounted for by differences which occur in the chemical and hydrophobic properties of their superficial waxes.Waxes isolated from leaves exhibiting contact angles less than 90° are usually more hydrophobic than the leaf surface itself. On most leaves exhibiting angles greater than 90° wax is the dominant factor governing water‐repellency, the isolated wax normally making at least a 60 % contribution to the contact angle measured on the leaf surface. Additional factors, such as roughness, responsible for the occurrence of contact angles greater than 110° on certain leaf surfaces, reside in the wax layer. The hydrophobic properties of some leaves are unaffected by chloroform washing, revealing that superficial waxes play little part in their wettability.
Oxygen and the hatch of eggs and migration of larvae of Meloidogyne javanica
Authors: BAXTER R. I. , BLAKE C. D. 
Published: February 2008

SUMMARYThe percentage hatch of eggs of Meloidogyne javanica increased asymptotically as the oxygen concentration increased from 0·2 to 21%. Hatch was unaffected by suction pressures of less than pF 3·4 at any oxygen concentration but was decreased by higher suctions. Both the development of embryos and the migration of larvae approached a maximum at an oxygen concentration of about 15%. Hatching was not limited by the rate oxygen diffused through the gelatinous matrix of the egg sac nor was the concentration of oxygen at the surface of an egg sac significantly lower than that within an individual egg. The maximum rate of metabolism appeared to need an oxygen concentration within the egg greater than 10%.
Studies on plant growth‐regulating substances XXVIII. Halogen‐substituted benzoic acids
Authors: JAMES C. S. , WAIN R. L. 
Published: February 2008

SUMMARYThe plant growth‐regulating activities of chloro‐, bromo‐ and iodo‐isomers in 2,5‐, 2,3,5‐ and 2,3,6‐substituted benzoic acids were assessed in the wheat cylinder, pea segment and pea curvature tests. Their effects in the tomato‐leaf epinasty test were also investigated.Replacing an ortho‐chloro atom by bromine had little or no effect on activity. An ortho‐iodo substituent, however, reduced activity in the 2,3,6‐substituted series and almost completely inhibited it in the 2,5‐ substituted series. This decreased activity of ortho‐iodo‐substituted isomers is visualized as being due to a steric inhibition of the attachment of the carboxyl group to its receptor unit prior to the initiation of the growth response.
Studies on plant growth‐regulating substances XXIX. The plant growth‐retarding properties of certain ammonium, phosphonium and sulphonium halides
Authors: KNIGHT B. E. A. , TAYLOR H. F. , WAIN R. L. 
Published: February 2008

SUMMARYWheat, pea and dwarf bean seedlings grown under controlled environmental conditions were used to assess the growth‐retardant activity of members of series of chloro‐substituted benzyl‐, trimethyl‐ and tri‐n‐butyl‐ ammonium bromides. The influence on activity of trialkyl groupings other than tri‐methyl and tri‐n‐butyl was also studied using compounds with the 4‐chloro‐benzyl ring structure. 3‐Chloro‐ and 4‐chloro‐benzyltributylammonium bromides were the most effective compounds. The activity was similar to that of 2,4‐dichlorobenzyltributylphosphonium bromide (Phosphon‐D) and they showed little phytotoxicity. A series of chlorophenoxymethyltributylammo‐nium and phosphonium salts were found to have lower activity than the corresponding chlorobenzyl derivatives. Allyldimethylsulphonium bromide retarded the growth of wheat seedlings but, like the aliphatic trimethylam‐monium bromides tested, it was only slightly active in the pea‐seedling test.The results are considered in relation to the chemical structure of the compounds studied. In particular, the influence of chlorine substitution in the ring of benzyltributylammonium salts on their growth‐retardant activity is compared with the effect of similar substitution on the auxin activity of phenoxyacetic acids.
Growth and yield of six short varieties of spring wheat derived from Norin 10 and of two European varieties
Authors: THORNE GILLIAN N. , WELBANK P. J. , BLACKWOOD G. C. 
Published: February 2008

SUMMARYFive short varieties of spring wheat derived from Norin 10: Lerma Rojo 64A (R), Penjamo 62 (P), Sonora 64 (S), Mexico 120 (M), and an unnamed selection obtained from Mexico (X), had grain yields equal to, or only slightly less than those of the taller European spring varieties Kloka (K) and Jufy I (J). Yields ranged from 500 to 580 g/m2 of dry matter. The short variety NBJ115 (N) was severely infected with yellow rust and yielded only 290 g/m2. Total dry weight (excluding roots) of the short varieties was less than of J and K; hence grain accounted for 49 % of the total for the short varieties and 42 % for J and K. Most of the short varieties had fewer ears than the tall ones because sowing difficulties and poor germination produced fewer plants. The relative yields of X, P, R and S seemed to be correlated with their plant and ear densities.Leaf area duration after flowering (D), based either on total green area or on green area above the flag‐leaf node only, was less for the short varieties than for J and K. The apparent mean efficiency of this area in grain production (grain yield divided by D) was 50% greater for the short than for the tall varieties.The height of the short varieties ranged from 43 cm (M) to 79 cm (N). K was 92 cm and J 97 cm tall. Differences in height depended on the lengths of the top four internodes and not on number of internodes. Main shoots of all varieties produced seven or eight leaves. All varieties initiated spikelets 45–48 days after sowing. The short varieties flowered 103 days and matured 155 days after sowing; J and K flowered and matured about 1 week earlier.
A survey of foliar diseases of spring barley in England and Wales in 1967
Authors: JAMES W. CLIVE 
Published: February 2008

SUMMARYA total of 5,250 acres of spring barley was sampled in proportion to the barley acreage in each of eight regions. The percentage leaf area ‘affected’ by each disease was recorded for the first (flag) and second leaves at a growth stage when the grain was milky ripe. The operation was automated by punching the data directly on to computer paper tape and a programme was written to analyse the results. Mildew was found to be the most important disease, causing an average loss in yield of approximately 18 %, followed in descending order by brown rust 3%, leaf blotch 1 %, yellow rust 1 %, halo spot 1 %. The total loss due to foliar diseases was estimated to be 20–25% of the national barley yield. Diseases were more severe in the southern than northern regions, e.g. mildew severity was three times higher because of the greater popularity of mildew‐susceptible varieties, and the prevalence of weather more conducive to mildew development. Disease severity was not related to previous cropping, and in general the February‐sown crops had more mildew than the April‐sown crops.
Persistence and transmission of Alternaria dauci (Kühn) Groves & Skolko in the semi‐arid conditions of Israel*
Authors: NETZER D. , KENNETH R. G. 
Published: February 2008

SUMMARY Daucus maximus, Ridolfia segetum and Caucalis tenella, members of the Umbelliferae, were found to be foliage hosts of naturally occurring Alternaria dauci in Israel. A. dauci was also isolated from Daucus maximus seed.When infected cultivated carrot petioles were stored dry for 3 months, A. dauci retained its ability to spore, which was lost, however, in alternating wet and dry conditions, an effect paralleled by the loss of mycelial viability in similar soil storage tests. A. dauci colonizing moribund foliage stayed viable longer when the foliage was on the surface than when buried in soil at depths of 10 and 20 cm.Viable thick‐walled hyphae of A. dauci were found in the inner pericarp layer of Japanese seeds from which infected seedlings developed.
The distribution of Myzus persicae (Sulz.) on year‐round chrysanthemums
Authors: WYATT I. J. 
Published: February 2008

SUMMARYLarge varietal differences in the susceptibility of chrysanthemums to Myzus persicae (Sulz.) were confirmed. The cultivar B.G.A. Tuneful supported forty times as many aphids as Portrait. In the winter, aphids bred more slowly and stabilized at a lower density than in the summer, but retained the same characteristic varietal distribution patterns.The unintentional introduction of the parasite Aphidius matricariae Hal. resulted in extermination of the aphid within 15 weeks. Mummies appeared in a series of distinct generations 17 days apart with a sevenfold increase between peaks. As this increase was at first not as rapid as that of the aphid, reduction of the pest population was not possible until the aphids had become self‐limiting. Thus, although elimination was achieved, it was not economically satisfactory on susceptible varieties. The modifications needed to employ A. matricariae for commercial biological control under glass are discussed.
The restriction of Cladosporium fulvum and Botrytis cinerea, attacking glasshouse tomatoes, by automatic humidity control
Authors: WINSPEAR K. W. , POSTLETHWAITE J. D. , COTTON R. F. 
Published: February 2008

SUMMARYDecreasing periods of atmospheric humidity in excess of 90 and 75 % r.h. by automatic control decreased the incidence of C. fulvum and B. cinerea and sometimes increased tomato yields. The desired value of humidity was not always achieved but nevertheless environments which were both physically and biologically different were obtained with humidistats set at 90 and 75 % r.h. in glasshouses maintaining two temperature régimes–20 °C day and night, or 20 °C by day and 13 °C at night.Less B. cinerea and C. fulvum occurred on tomatoes grown constantly at 20 °C than on those grown in conditions with lower night temperatures. In the latter regime the end‐of‐season incidence of C.fulvumvas decreased from 25.0% where humidity was not controlled to 2.8% and 0.0% where humidistats were set at 90 and 75 % r.h. In the same conditions the proportion of blemished fruit damaged by B. cinerea decreased from 2.6% to 1.6% and 0.2%.
Biochemical changes in French bean pods infected with Colletotrichum lindemuthianum*
Authors: SMITH I. M. 
Published: February 2008

SUMMARYInfection of bean pods with Colletotrichum lindemuthianum leads to the appearance in diffusates of a range of fluorescent and phenolic compounds and of at least two inhibitory compounds. These compounds were found to be absent or in reduced concentration in control diffusates, although the inhibitors were frequently observed to appear at low concentrations without infection. Although sugars and amino acids were found to be released into diffusates, variation in the concentration of these stimulants was found to have little effect on spore germination. Evidence from solvent partition, spectrophotometry and chromatography suggests that the two inhibitors can be tentatively identified with inhibitors previously described from French bean, and both appear to be phenolic substances. It is suggested that inhibitor production may be regarded as part of a general change in aromatic biosynthesis following infection.
The effect of different virus isolates on the expression of tolerance to barley yellow dwarf virus in barley
Authors: JONES A. T. , CATHERALL P. L. 
Published: February 2008

SUMMARYA barley variety of Ethiopian origin, with a single Mendelian gene con‐fering tolerance to barley yellow dwarf virus (BYDV), was equally tolerant to a number of isolates of the virus, whereas a susceptible European barley was more susceptible to isolates transmitted by Rhopalosiphum padi L. than to those transmitted by Macrosiphum (Sitobion) avenae (Fab). However, hybrids between these two varieties homozygous for the Ethiopian tolerance gene were more tolerant to ‘mild’ than to ‘severe’ isolates, irrespective of the vector specificity. The European variety was damaged more severely by all isolates when infected early than when infected late in its development, but the hybrids were damaged more severely by M. awraae‐transmitted isolates when infected late.It is suggested that in susceptible plants the concentration, rather than the virulence, of the virus determines disease severity, whereas the reverse is true in plants possessing a gene which reduces virus multiplication. Virus concentration appears to determine the severity of R. padi‐transmitted isolates, while virulence determines the severity of M. avenae‐transmitted isolates. The latter would also seem to be adapted towards late infection.
Effects of population density on alienicolae of Aphis fabae Scop.
Authors: SHAW M. J. P. 
Published: February 2008

SUMMARYA wide range of morphological differences, from apterae to alatae, and of differences in the behaviour of alatae were produced by isolating alatiform nymphs of Aphis fabae on successive days after their birth. Alatiform. nymphs isolated soon after birth developed into the extreme apterous form, whereas when kept in a crowd until shortly before their final ecdysis a large proportion became alatae that flew before depositing young (migrants). Alatiform nymphs isolated on successive days after birth developed either into alatae that flew after depositing nymphs (flyers) or did not fly (non‐flyers). Aphids thus show a continuous polymorphism, comparable to that of locusts, and possibly related to concentrations of juvenile hormone present in the aphid during larval development.
Contribution to the biology of the citrus bud mite, Aceria sheldoni (Ewing) (Acarina: Eriophyidae)*
Authors: STERNLICHT M. 
Published: February 2008

SUMMARYIn laboratory studies mites of Aceria sheldoni were reared on citrus fruit peels, beneath coloured cellophane hoods, to cater for their thigmotaxis and sensitivity to light of particular wave lengths. Hatching was most successful at 25°C and 98% r.h. but was reduced by low humidities (35–40% r.h.), when abnormal dwarf larvae emerged. The eggs hatched in 3–14 days; the length of a generation (egg to egg) was 12–33 days.The threshold of embryonic development was 9 °C and that for completion of the life cycle, egg to egg, was 12.5 °C. The average number of eggs laid per female was six (4–8). It increased to twelve (5–19) if the mite, during its larval stages, had been fed on buds. The vitality of both the eggs and the mature mites was tested by exposure to extreme low and high temperatures (below 0 °C, 39 °C): 50% of mites died after 30 min at 30 °C; 50% died after 30 min at –15 °C or lower.
The control of Septoria on celery seed
Authors: MAUDE R. B. 
Published: February 2008

SUMMARYIn studies on the control of Septoria on celery seed, ¼ and 1 lb (113 and 454 g) samples of infected seed treated by the thiram‐soak method produced disease‐free seedlings under glass and disease‐free plants at maturity in the field. Hot‐water treatment of infected seeds, however, failed to give complete disease control in either situation. Thiram soaking was not harmful to seed germination and produced field crops of equal quality to those obtained from hot‐water‐treated seeds.In N.A.A.S. extension trials a total of 18½ lb (8.3 kg) of celery seed was treated by the thiram‐soak method and effective disease control was obtained in crops raised from this seed throughout the country.
Resistance of tomatoes to late blight (Phytophthora infestans)
Authors: GÜNTHER ELISABETH , EGGERT DÖRTHE , GRÜMMER G. 
Published: February 2008

SUMMARYRace T1 of Phytophthora infestans was first isolated in Central Europe. Tomato varieties carrying the dominant gene Ph were easily infected by T1 but showed a different degree of field resistance. In September 1967 more than 80% of all isolations from the experimental plots at Greifswald were determined as the aggressive race T1. This race was also isolated in a large screening test over several provinces of the GDR from potato and tomato fields where no plants carrying dominant resistance genes were present in the neighbourhood.The fungus was able to pass from potato leaves or tubers to detached tomato leaves or intact tomato plants (cv. Fanal) without any reduction in sporulation.The field‐resistant tomato variety Ružový Ker and the highly field‐resistant variety Atom were crossed. In F2 and subsequent generations, young plants were selected following inoculation of 14 mm leaf‐discs. Weak sporulations on the leaf‐discs were almost invariably correlated with a reduced level of infection of fruit in the field. Data from crosses of Atom with more or less susceptible varieties suggested the presence of incompletely dominant genes. It is concluded that at least two genes in the variety Atom control field resistance and the gene‐symbols Phf and Phf‐2 are proposed for them.
Methods of isolating the microflora of moulding, high ‐moisture barley in partially sealed silos
Authors: MULINGE S. K. , CHESTERS C. G. C. 
Published: February 2008

SUMMARYFungi were isolated on agar from barley stored at 18–44% moisture content in partially sealed silos by plating out whole, untreated grain as removed from the silos; surface‐washed whole grain; surface‐washed and then sodium hypochlorite‐sterilized whole grain; hypochlorite surface‐sterilized, dehusked grains cut vertically and plated with cut surfaces to the agar; husks washed several times after removal and plated as small groups. 5 mg aureomycin/100 ml agar was used to suppress bacterial growth. These methods are compared with others in common use.The isolated species have been tabulated to illustrate the various combinations occurring in grains and in aggregates of husks.
Carnation Italian ringspot virus
Authors: HOLLINGS M. , STONE OLWEN M. , BOUTTELL GINA C. 
Published: February 2008

SUMMARYCarnation Italian ringspot virus (CIRV) was obtained only twice in tests on several thousand carnations in Britain during 15 yr. The two isolates, from cultivars ‘Dusty Sim’ imported from Italy and ‘Orchid Beauty’ from the U.S.A., were indistinguishable serologically and in host reactions. CIRV was cultured in Nicotiana clevelandii and assayed in Chenopodium amaranti‐color; it was readily transmitted by leaf‐rubbing inoculation to 62 of 104 plant species tested. Virus‐free carnations were infected only by injecting purified preparations into the stem, and developed chlorotic spots and oval rings in the younger leaves. CIRV was eliminated from Nicotiana clevelandii plants grown for 8 weeks at 36°C. CIRV presents no threat to carnation growing in Britain.In N. clevelandii sap, CIRV was infective at a dilution of 1/50000 to 1/100000, after heating 10 min at 85 °C (but not 90 °C), and after 16 weeks at 16 °C or 23 weeks at 2 °C. After freeze‐drying, the virus survived at least 7 yr storage under vacuum at room temperature. CIRV was still infective and antigenic after treatment for 30 min at 18 °C with ultraviolet radiation (750 μW/cm2), ultrasound, 2% formaldehyde or 0.2% tri‐sodium ortho‐phosphate (TSP). Infectivity was not wholly abolished in 30 min by 2% TSP. The virus was readily purified by overnight maceration of N. clevelandii leaves extracted in phosphate buffer + butanol, followed by differential centri‐fugation. Purified preparations contained abundant isometric particles c. 29 nm diameter, and like other serotypes of the tomato bushy stunt‐pelargonium leaf curl group, gave three or four specific bands in density‐gradient centri‐fugation. The bands corresponded to four Schlieren peaks in analytical centrifugation. Virus from the lower bands was usually less invasive in N. clevelandii than from the upper bands, although the material in the different bands contained similar amounts of nucleic acid. Only one antigenic component was found by Immunoelectrophoresis; different serotypes of the TBSV‐PLCV group differed widely in immunoelectrophoretic behaviour. The present cryptogram of CIRV is */*:*/*:S/S:S/*.
Attempts to eliminate chrysanthemum stunt from chrysanthemum by meristem‐tip culture after heat‐treatment
Authors: HOLLINGS M. , STONE OLWEN M. 
Published: February 2008

SUMMARY‘Mistletoe’ chrysanthemums infected with stunt were grown at 35°C for 14–37 weeks, and meristem‐tips cultured from them at intervals. Of 337 meristems, seventy‐two survived to plants but their development took 50% longer than did that of stunt‐free meristem‐tips. All plants were symptomless for at least 5 weeks after planting in 75 mm pots of soil‐mix, and only three showed symptoms after 9 weeks. No more plants developed symptoms during the next 5 (winter) months, but between mid‐March and late May sixty‐seven did so. Only two plants were freed from stunt. ‘Mini‐cuttings’ rooted from shoot tips of infected chrysanthemums grown at 35°C for 37 weeks all developed stunt symptoms within 27 weeks.
Augusta disease in tulip ‐ a reassessment
Authors: MOWAT W. P. 
Published: February 2008

SUMMARYIn an experiment in which the roots of field‐grown tulip were commonly infected with tobacco necrosis virus (TNV), Augusta disease did not develop in the year of infection or when progeny bulbs were grown in the field or glass‐house. When tulip bulbs of other stocks, including grades of 11 and 12 cm circumference, were forced, the disease developed sporadically, in some instances as the result of infection with TNV from the soil in which they were planted and in others as a result of infection by bulb‐borne virus. The incidence of disease produced by current year infection was increased by warming the plunge bed.Different strains of TNV were obtained from field‐grown plants with Augusta disease and different strains of the virus produced the disease when inoculated to tulip. Some, but not all, naturally diseased plants contained satellite virus, which therefore does not cause or prevent disease development. The disease was produced in some plants by TNV transmitted by Olpidium brassicae, but neither a vector nor a non‐vector isolate of O. brassicae completed its life cycle in tulip. However, Olpidium‐like zoospores were observed in some washings of tulip roots from TNV‐infested soils.TNV was not obtained from all tulip plants with necrotic leaf symptoms resembling Augusta disease. Some were infected with tomato bushy stunt virus or cucumber mosaic virus, or with another agent that was transmitted by inoculation of sap to Nicotiana clevelandii and Chenopodium quinoa, and carried by bulbs of up to 11 cm circumference.