摘要:

Summary1An experiment with three varieties of potatoes (Great Scot, Kerr's Pink and King Edward) was carried out during the period 1922–24 in order to test the physiological theory of potato deterioration by determining whether the cropping power was influenced by early lifting or affected by shading the growing plants and so protecting them from overheating. The main results of this experiment were as follows:aIn the absence or very limited presence of virus disease, neither early lifting nor shading produced any significant effect on crop yield. All the types of seed (one‐year grown, two‐year grown, early‐lifted, etc.) gave yields which were not significantly different from that of fresh Scotch seed.bWhen considerable infestation with virus disease was shown, all the types of English‐grown seed showed a significant falling off in yield as compared with Scotch seed. In such cases the falling off in yield was not so great with seed which had been lifted at a very early date. Thus, with virus disease present, an advantage may be gained by early lifting of the seed.cIn one case, evidence was obtained that very immature seed is intrinsically inferior in cropping power to seed lifted at the normal time, i.e. apart from the effects due to the unequal distribution of virus disease.dIn two cases the greater cropping power of one‐year grown English seed as compared with fresh Scotch seed was demonstrated. This difference is probably to be explained on the ground of the unequal sprouting at the time of planting.eA general correlation was observable between the amount of virus disease present in the various plots and the falling off in cropping vigour.fNo effect of a purely physiological nature arising from early lifting or from shading was indicated. Though such an effect could not be disproved, it was clear that it was of minor account and quite subsidiary to the effects of virus disease.2An experiment was carried out over the period 1925–8 to determine whether, by a process of rogueing, the cropping vigour of a deteriorated stock could be restored. The weight tests carried out in 1928 showed that certain English‐grown stocks, some of which were in their seventh year from Scotland, yielded as heavily as Scotch seed.3The experiments were carried out in such a way that the statistical significance of the data obtained could be assessed. In thirty‐three such experiments, where the yield of English‐grown types of seed was compared with that of Scotch seed, the percentage drop in cropping power which was significant varied from 7.0 to 20.0. Over the whole series, the average figure was 11.8 per cent., corresponding to a falling off in yield of about 1.2 tons per acre.In conclusion we wish to record our thanks, for facilities offered for this work, to the Director of the Rothamsted Experimental Station and to the Principal of the South‐Eastern Agricultural College, Wye, and the Principal of the Harper‐Adams Agricultural

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07330.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07331.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

Summary1Myzus persicae Sulz. is suggested as a vector of the virus of transmissible variegation known as “breaking” in tulips.2“Red‐streak break” is associated with Myzus persicae.3Macrosiphum gei Koch possibly carries “break” in a lesser degree and is associated with “white streak.”4Anuraphis tulipae B. de Fonse. and Rhopalosiphoninus tulipaella Theo. have both so far shown

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07332.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

Summary1The occurrence of Gibberella Saubinetii (Mont.) Sacc. on wheat and barley grown in England is recorded, but the extent to which it occurs in this country is not known.2The methods by which it was isolated and grown in pure culture are described.3The complete life cycle of this “strain” has been carried through from single‐conidium and single‐ascospore pure cultures.4The diagnostic characters are given, and the identification verified.The writer tenders thanks to Dr G. H. Pethybridge for assistance rendered.(Since writing the foregoing article the writer has isolated G. Saubinettii from the bases of wheat, barley and T. monococcum plants grown in the Eastern Counties. 23

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07333.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

Summary1An organism has been isolated from lesions on leaves, shoots, and fruit of young walnut trees at the East Mailing Research Station, Kent.2This organism was proved to be pathogenic by positive results obtained from inoculation on walnut leaves and shoots.3It corresponds closely to descriptions of Pseudomonas juglandis and is therefore referred to that species.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07334.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

Summary1A study of the relation of atmospheric temperature and humidity to tomato leaf mould (Cladosporium fulvum) has been made with a view to assisting growers to control the disease by cultural methods.2The optimum temperature for the various stages of leaf mould is about 22° C. At 10° to 15° C. severe infection occurs under humid conditions, but the disease develops very slowly.3Humidities exceeding 90 per cent, are very favourable. At 22° C. infection is severe at 80 per cent, humidity but is rare at 70 per cent. At 18° C. infection and subsequent development are considerably retarded at 80 per cent, humidity.4Experiments indicate that seasonal variations in the severity of leaf mould are related to temperature.5Data are given which show that humid conditions obtain in large glasshouses for several hours each night and that these conditions are largely responsible for the severity of leaf mould.6Wetting of the foliage caused by overhead watering does not appear to favour the disease. Excessive watering produces turgid, susceptible plants.7A basis for controlling leaf mould by cultural methods is sugge

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07335.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

Summary1The effect on the tomato crop of atmospheres enriched in respect of carbon dioxide liberated by two methods with possibilities of commercial application, (1) a fermentation process, and (2) a portable stove, is compared with that of carbon dioxide liberated by acid from sodium bicarbonate.2The concentration of carbon dioxide obtained from the fermentation process was insufficient to give any increase in yield. Using the stove method, which gave a concentration of at least 18 parts per 10,000 for 1.5 hours twice daily, the average increase in crop was 16 per cent. where plants were treated throughout the season and was 9 per cent. where they were treated for the first half of the season only.3Relatively high concentrations of carbon dioxide are shown to be normally present in cucumber houses. It is suggested that, under the weak light conditions prevailing in such houses, the concentration is sufficient for the requirements of the crop.4Mechanical mixing of the carbon dioxide and air is not essential from the standpoint of crop production.5In the case of tomatoes grown in enriched atmospheres, the cultivation of two crops, planted January and June respectively, was not profitable under the experimental conditions.6The stove method of treatment is discussed in relation to commercial practice.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07336.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

SummaryAn account is given of the construction of tanks and chambers for the growing of plants under independently controlled soil and air conditions. The plants are grown in soil tins sunk in a water tank, the temperature of which is automatically controlled. Double‐walled glass chambers fit over the tanks, and within these the conditions of temperature and humidity are independently controlled. Artificial illumination is provided by two floodlights over each chamber, with 500‐watt gas‐filled lamps in each providing an illumination of the order of 1000 foot‐candles. The chambers were erected under a grant from the Empire Marketing Board for research on the bacterial disease of

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07337.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07338.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY

摘要:

SummaryThe results of a prolonged investigation of the fungicidal properties of solutions containing sulphur in polysulphide form upon the hop powdery mildew (S. Humuli) have been classified and summarised. During the course of this work the fungicidal efficiency of various lime sulphurs, liver of sulphurs, and solutions containing sodium, potassium, ammonium, calcium and barium polysulphides have been compared and it has been shown that, in all cases, the effect upon the fungus, when growing under similar biological and external conditions and provided that the sprays are applied under standardised conditions, is determined solely by the content of polysulphide sulphur of the spray fluid. The estimation of the amount of polysulphide sulphur present provides, therefore, a measure of the efficiency of these materials against S. Humuli.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1930.tb07339.x

出版商:Blackwell Publishing Ltd    

年代:1930

数据来源: WILEY