摘要:

SUMMARYFive colour characteristics were studied in seventeen carrot trials in which four varieties of the Chantenay type and four of the Autumn King type were grown at two densities at several sites for 3 yr. The Chantenay type had lower percentages of green‐topped and green‐cored roots and a higher score for internal colour; the Autumn King type had a lower percentage of purple‐topped roots. Differences between varieties within types were also detected. Large environmental effects mainly resulted from differences between individual trials. Percentages of discoloured roots were higher at the low density.Genotype × environment (GE) interactions of practical importance were detected for all characters except internal colour. Some of these interactions were adequately described in terms of different linear regression coefficients for the genotypes, when genotypic values were regressed on environmental means. The results indicate that a low density should be chosen when selecting for reduced discolorations. Broad‐sense heritabilities, estimated from variance components for the genotypic, environmental and GE effects, show that the most efficient selection for a colour character, in one season and with four test plots per family, would be achieved when such plots were grown at four separa

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01653.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe wheat cultivar Hybride de Bersee is described as possessing durable resistance to yellow rust. Some races ofPuccinia striiformiscan infect it at the seedling stage but not severely in the field. Using euploid and aneuploid stocks of Bersee it was shown that a large part of this resistance was controlled by chromosome 5BS‐7BS, the effect being detectable in seedlings and at later growth stages. Measurements of spore production from infected seedlings showed that the line ditelosomic for the 5BS arm of the chromosome was more resistant than the line ditelosomic for the 7BS arm under environments favouring high spore production, but more susceptible under environments favouring low spore production. Thus both arms of the chromosome could contribute to resistance in appropriate environments. Chromosome 5BS‐7BS did not carry the factors controlling the race‐specific resistance to race 37 E132 ofP. striiformis.The possibility of exploiting the resistance carried by chromosome 5BS‐7BS in wheat breeding programmes is di

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01654.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe field occurrence of symptoms of beet western yellows virus (BWYV) disease in breeding lines of summer lettuce was studied in trials conducted from 1971 to 1974. No evidence of immunity was found in seventy cultivars and over 500 lines from ten crosses, but some lines, notably those with Little Gem as one parent, appeared to be less affected by the disease.When the number of plants showing symptoms was recorded on a weekly basis it was apparent that only minor differences existed in the response to infection. In the earlier maturing lines, 50 % of the plants exhibited symptoms within 16 to 20 days of hearting, and later maturing lines reached the same level of disease incidence within 7 to 16 days after hearting.The search for resistance should be widened to include wild species; strict selection techniques up to flowering time should also be used to increase field resistance in the present cultivars.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01655.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYRates of carbon dioxide production, in air and in 3 % 02, over a range of temperatures, were measured for over thirty commodities, and rates of evaporation, under known water vapour pressure deficit, measured for most of them. Optimum storage conditions in air for each commodity were determined. Storage life under these optimum conditions, and under the nearest practical approximation to them, was estimated. In most cases the optimum temperature is ooC, examples of exceptions being runner beans, cucumbers, potatoes, green peppers and tomatoes. The humidity should usually be high, 100 % r.h. often being optimal, particularly for leafy vegetables, provided the temperature is low. Commodities resistant to evaporation, however, such as the onion, may with advantage be stored at lower humidities, thus reducing the microbial hazards.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01656.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe incidence of tobacco mosaic virus (TMV) Strain 1 in tomato crops of TMV‐susceptible cultivars increased from 12% in 1971 to 64% in 1974. This change coincided with the introduction of cross protection to reduce the effects of tomato mosaic. Of the isolates collected from nurseries where the technique was used in 1974, 94% were of Strain 1 compared with 39 % from the other nurseries. No new strains were found and all the isolates were tomato forms of TM

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01657.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThree biologically distinct strains of bean yellow mosaic virus (BYMVS, BYMV1PV‐2) were partially purified by centrifugation at relatively lowgforces. Serologically these strains appeared to be distinct from each other but were relate

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01658.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYA modification of the Boyd method is described in which cores of potato tissue are used instead of whole tubers. This reduces the space required for incubation, permits good control of the environment and eliminates the need to sacrifice valuable seed material. The method was used for testing the resistance of sixteen cultivars of potato on five occasions over two seasons.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01659.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYBenomyl sprays, applied monthly from September to January, increased the survival and dry‐matter yield of red clover and decreased the numbers of apothecia ofSclerotinia trifoliorum.Two sprays increased dry‐matter yield in the first harvest year, if applied between October and December, but decreased yield in the second harvest y

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01660.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYForty varieties of vegetable, cereal, fodder and grass seeds at 10, 13 and 16% moisture content were fumigated with methyl bromide at 10 and 18oC, to determine the maximum safe moisture content required to avoid unacceptable phytotoxicity. Dosages (concentration x time products) of 200 and 400 mg h/1 of technical and commercial methyl bromide were used and treated seeds were compared with controls in germination tests. Results were not consistent, but inc.30 % of the comparisons lower moisture contents, lower temperature and lower dosage each resulted in better germination than the corresponding higher values. The reductions in germination of treated samples were usually less than 5 % and the overall average reduction was only 2.3%. This work showed that under controlled conditions the treatments are safe for most of the tested varieties of seed, but for some seeds, particularly white clovers,Agrostisand runner beans, the highest moisture content (16%) should be avoided.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01661.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYTests were made with a glasshouse whitefly population resistant to both DDT and parathion to measure resistance to two organochlorine, eight organophosphate and six carbamate compounds; resmethrin and pyrethrum were also included in the tests. The whiteflies showed marked resistance to endosulfan, thionazin, malathion and resmethrin and low resistance to all other compounds.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb01662.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY