摘要:

There is considerable varietal variation in the characteristics of the potato. The characteristics of any one variety of potato may be very greatly modified by environmental conditions. Rainfall and percentage dry matter may be inversely correlated, as may rainfall and yield in localities with a medium or high precipitation. There is an apparent correlation between time of maturity, percentage dry matter, and texture when cooked, late varieties having a higher percentage dry matter and a more floury texture than early varieties. It is a fundamental requirement of potatoes for drying purposes that they should not discolour on cooking. In addition the texture of the cooked potato should be suitable for the method of drying employed, and for the type of reconstituted product desired, and the percentage dry matter should be as high as is compatible with the foregoing conditions.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06216.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

In the summer of 1941 chocolate spot of beans was widespread in the South‐Eastern Agricultural Province and caused much damage to the crop. Soil samples were collected from forty‐nine affected fields on a variety of soil types, and the relation between the severity of attack by chocolate spot and the texture, pH, available potassium and available phosphorus determined. Severity of attack was classified into three grades: ‘slight’, in which only spotting of the foliage occurred; ‘moderate’, in which death of leaves and blossoms on the three or four lowest nodes occurred; and ‘severe’, in which there was generally a total loss of crop. No significant relation between severity of attack and soil texture, pH or available potassium was found. A highly significant relation was found to exist between the severity of attack and the amount of available phosphorus in the soil as determined by the method of soil analysis used in this Province. Damage by chocolate spot was generally slight on soils containing ‘medium to medium high’ or higher amounts of available phosphorus, and generally severe on soils containing low amounts of a

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06217.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Ophiobolus graminis var. Avenae has been found on oat crops in ten counties in Scotland. It has also been shown to attack wheat crops in the same districts.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06218.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The literature relating to the growth of moulds at different humidities is surveyed.Observations were made on the development of mould growth on six widely different types of feeding‐stuffs for storage periods extending over some 3 1/2 years. The main factors controlling mould growth were found to be:1. The relative humidity rather than the moisture content of the food.2. The length of the storage period. Mould growth took place relatively quickly on all feeding‐stuffs stored at 100‐75% R‐H. Below 75% R.H. mould growth, while not prevented, only developed after a very prolonged latent period. Mould development was observed on locust beans exposed to a humidity as low as 65 % after a latent period of over 2 years.3. The balance and type of nutrients provided by the various feeding‐stuffs was shown to influence the latent period as well as the extent of mould deterioration. This was confirmed by experiments on artificially dried grass fractions and by experiments on starch, protein and fibre mixtures.4. The temperature of storage was found to affect the rate of mould development; mould growth developed sooner on samples stored at 22d̀C. than at 15.5d̀C.5. The type of mould species present. At high humidities all mould species grew rapidly: at low humidities, only a few types were capabl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06219.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The water uptake of a wide variety of feeding‐stuffs was determined over a range of fixed humidities. It was shown that the level and shape of the water uptake curves are closely related to the amounts of soluble carbohydrate and protein present. Fibre exerts a depressing effect on the water uptake, while the value is also lowered by the presence of inert fats and non‐hygroscopic ash constituents. These conclusions were confirmed by direct experiments on the water uptake of samples of pure starch, protein and fibre.The results of the investigations have enabled safe limits of moisture content to be laid down, for both short‐ and long‐period storage, below which mould growth will not normally take place. These limits vary for each individual feed, representative figures being included in the paper in tabul

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06220.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Specific antisera have been prepared against the sap expressed from beet plants infected with beet yellows virus.The antigen is unstable. In the sap it is destroyed by keeping for 2‐3 days at room temperature or by heating for 10 min. at 52d̀C. It is unaffected bypH changes between 5 and 9. In detached leaves at room temperature it remains unchanged for at least 6 days, whereas the ability of aphides to transmit from these leaves fell considerably in 4 days.The antigen can be reversibly precipitated by ammonium sulphate or sedimented by high‐speed centrifugation. However, all the attempts to isolate it from other sap constituents or concentrate it have failed.The precipitin reaction is of value for diagnosis, and works successfully with crude

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06221.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The microbial population of the caecum of rabbits and guinea‐pigs, respectively, normally exhibits distinctive features which can be tabulated precisely, and which persist when the animals are kept in the same cage and fed on the same diet. A pronounced resistance, therefore, opposes cross‐infection and tends to secure the stability of the population whose characteristics afford useful criteria for the microbiological control of in vitro incubation experime

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06222.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

An account is given of a severe attack to grassland by chafer‐beetle larvae in some north Wales valleys in the years 1942‐3. The species concerned were Phyllopertha horticola L. and Hoplia philanthus Fuess. Estimations of the populations of both species were made and notes are given on the biology and comparative morphology of their immature stages. Both species have a one‐year life cycle; all stages of Hoplia philanthus occur somewhat later than Phyllopertha hort

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06223.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

A brief review of recent papers onTribolium destructorUytt. is given, and its potential danger as a pest noted. It is shown that 85 % extraction flour leads to about double the fecundity found on 60 or 75% extraction flour. The pre‐oviposition period is shown to be affected by both larval and adult food. Unfertilized females lay eggs, but these are relatively few in number, and are all sterile. Oviposition appears to be stimulated when males associate with unfertilized females, and also when they are removed from fertilized females: the presence of five males seems to lead to greater oviposition than when only one male is present, but the use of small numbers makes these conclusions rather insecure. Although copulation occurs at frequent intervals, females will lay viable eggs for as long as 250 days after the removal of the male. Fertility remains virtually constant throughout life when males are present, and is not increased by the presence of more than one male. Fertility varies inversely with the number of eggs laid. The oviposition period is long and the average curve has a characteristic form, despite considerable daily and individual fluctuations. Oviposition may continue until death or may end some weeks before. Poor conditions tend to lengthen both the oviposition period and the length of life, the latter being greater for males than for female

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06224.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The mode of action of inert dust insecticides on the grain weevil (Calandra granariaL.) has been investigated by determination of mortality‐time curves and by a detailed study of the influence of dusts on the water relations of the insects. It has been found that dusts do not depend for their action on any chemical reactivity, some highly inert substances such as diamond and carborundum being very effective. A physical process is therefore indicated.Dusts do not penetrate into the respiratory system, and although large amounts are ingested these seem to have little harmful effect.It has been demonstrated that effective dusts increase the rate of evaporation of water from insects to the air, and that the relative killing powers of different dusts run parallel with their capacities for promoting evaporation. The results are in harmony with the view (proposed by earlier workers) that inert dusts kill insects by inducing death by desiccatio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06225.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY