ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05878.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

By growing the excised apical meristems of sprouts from the potato varieties King Edward and Arran Victory, infected respectively with potato paracrinkle virus and potato virusS, virus‐free plants were obtained. Although the method failed to produce virus‐free plants from varieties infected with potato virusX, this virus also seems not to be present in apical meristems, for no virus could be demonstrated in callus tissue that developed from excised meristems less than 200 μ across. The concentration of tobacco mosaic virus in tomato roots and tobacco stems is also much less near the growing point than in older cells, but there is no evidence that the meristematic region is virus

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05879.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The prevention of chlorosis in flax by high concentrations of molybdenum in a nutrient solution was associated with a delay in the precipitation of iron from ferric citrate, a slower drift of pH towards alkalinity and an increase in the iron content of the root. These effects were greater with ammonium than with sodium molybdate and occurred with solutions started at pH 4.6 but not at pH 6.6.When FeEDTA was the source of iron, a similar delay in pH drift in the solution and accumulation of iron in the root occurred, but there was no chlorosis or precipitation of iron in the control treatment, so the effect of high molybdenum could not be fully determined.When ferric chloride was used, high molybdenum did not prevent chlorosis nor delay iron precipitation or cause accumulation of iron in the root, though the rate of pH drift resembled that of solutions containing the organic forms of iron.Similar results were obtained with peas and soybeans receiving high molybdenum treatment, but suppression of chlorosis was only temporary.It is suggested that the capacity of molybdenum to offset chlorosis is due to the formation, in acid solution, of a complex with phosphorus which renders iron more available by delaying the formation of ferric phosphate. This seems to occur only when iron is supplied in the organic form.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05880.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The susceptibility of tomato plants to systemic infection by tomato spotted wilt virus was increased by increasing nitrogen supply to levels above that optimal for growth. The virus content, estimated by local‐lesions counts, was also raised by increasing nitrogen. The period between inoculation and the appearance of systemic symptoms was decreased by increasing nitrogen to a point slightly greater than the optimal level for growth, but increased by additional applications.Infected plants receiving more nitrate or ammonium compounds than were needed for optimal growth showed abnormal leaf symptoms and no bronzing. N, P and Mg analyses showed that these symptoms were related primarily to nitrogen content. Such leaves contained more virus than bronzed leave

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05881.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The rate of photosynthesis of tobacco leaves infected with the Rothamsted type culture of tobacco mosaic virus was lower than that of comparable healthy tobacco leaves. The lower rate was inferred from Net Assimilation Rates of whole plants and confirmed by direct comparisons of photosynthetic rates of inoculated and healthy leaves. The effect began within 1 hr. of inoculation. It was not caused by an effect of the virus on the stomata, and inactivated virus inoculum did not change the rates. The results indicate either a more rapid movement of virus from the epidermis into the chlorenchyma than has been previously recorded or an effect of virus infection at a site distant from the cells containing virus.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05882.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

An apparently undescribed mechanically transmissible virus has been named beet ringspot virus (BRV). It occurs naturally in Scotland in sugar‐beet, turnip, swede, potato and many kinds of weed plants. BRV is readily distinguished from raspberry ringspot virus by the symptoms produced inChenopodium amaranticolor, French bean, tobacco andPetunia hybridaplants. BRV lost infectivity when heated for 10 min. at 63°C. but not at 60°C.: at 20°C. its longevityin vitrowas about 3 weeks. BRV was precipitated by ammonium sulphate, ethanol and acetone.Protection experiments with tobacco plants, and serological tests, gave no evidence that BRV was related to tobacco ringspot, raspberry ringspot, potato bouquet or tobacco rattle viruses, but showed that viruses isolated from different host plants and from different localities were strains of BRV.BRV is soil‐borne: in glasshouse experiments sugar‐beet, beetroot, potato, turnip, swede, French bean,Fragaria vesca, oat and wheat plants often became systemically infected when grown in soil from the site of a disease outbreak, but the virus was restricted to the roots of many infected plants. When sugar‐beet seedlings were grown in virus‐containing soil, BRV was first detected in their roots, where its concentration increased, before progressively increasing amounts of virus were found in the shoots.Soils from five localities were found to contain BRV. BRV has been found only where the soil is light in texture, and often in fields where raspberry ringspot

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05883.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

A 13‐acre plot of cacao, in an area devastated by swollen shoot, was treated by dimefox applied to the soil nine times. The plot was examined every month and trees recorded as they showed symptoms. The number of such trees decreased very rapidly a year after the first treatment and remained low for the 3 years that the experiment was continued. This suggests that the time between infection and symptom development can extend to about I year. The cause of the continued appearance of a few diseased trees could not be determined.As cacao farms differ from one another, it was difficult to find suitable control plots. Three farms in the neighbourhood of the chemically treated area were selected. The initial percentage of diseased trees in each was lower than on the chemically treated plot. The three farms were inspected every month and newly discovered trees with symptoms were felled. The number of such trees decreased 12 months after the initial cutting out and then increased abruptly until it again reached a high level.Chemical treatment combined with cutting out was more efficient than cutting out alone in arresting the advance of the diseas

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05884.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

MCPA applied to oats at the 1‐ to 2‐leaf stage had slight effects on grain quality, whereas 2:4‐D at this stage generally increased kernel weight, husk ash content, and content of abnormal grains, and decreased the grain yield. Applied at the 4‐ to 5‐leaf stage, 2:4‐D also increased kernel nitrogen content and decreased kernel oil content. Effects were enhanced as the dosage increased. Yielder and Craigs Afterlea were most susceptible to 2:4‐D at the 4‐ to 5‐leaf stage; Sun II, a relatively resistant variety, at the 6

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05885.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

Maleic hydrazide (MH) and gibberellic acid (GA) were applied alone and in combination at various doses to dwarf and tall varieties of garden pea, and their effect on stem extension measured. Combinations of MH and 3‐indolylacetic acid (IAA) were also studied. Stern extension of dwarf peas was accelerated by GA and inhibited by MH. Their effects were not additive, since MH reduced the response to GA at all concentrations of each tested. IAA did not affect stem extension, whether applied alone or in combination with MH. Stem extensions of tall peas was not affected by GA or IAA alone. MH severely inhibited growth and this inhibition was not reduced either by GA or by IAA. At low doses MH broke apical dominance and side branches developed; extension of these was stimulated by GA and IAA and extension of the main axis correspondingly still further reduced. The results show that MH prevents the response to GA of GA‐sensitive plants. It is suggested that the rapid growth of tall peas, as compared with that of dwarfs, and their lack of response to GA, are due to a greater capacity to synthesize a ‘GA‐like hormone’. Growth of tall peas is much more drastically inhibited by MH than that of dwarf peas and the suggestion is made that the inhibition of shoot growth induced by MH is due primarily to blocking the activity of the postulated ‘GA‐

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05886.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY

摘要:

The linear growth ofBotrytis cinerea, Fusarium caeruleumandPhoma foveatain culture was reduced in the presence of vapour from any of the three isomers of tetrachloronitrobenzene. The isomers were fungistatic but not fungicidal.Differences in activity were observed amongst the isomers. The 2:3:4:6 isomer was the most active against all three test fungi. 2:3:5:6‐TCNB (tecnazene) was more active than 2:3:4:5‐TCNB againstBotrytis cinerea, but less active againstFusarium caeruleumandPhoma foveata. Two strains ofFusarium caeruleumresistant to the 2:3:5:6 isomer were not resistant to the other two isomers, although they were more resistant than their 2:3:5:6‐TCNB sensitive parent strains.Sporulation and sclerotial production byBotrytis cinereawere completely suppressed by 2:3:5:6‐TCNB and 2:3:4:6‐TCNB but not by the 2:3:4:

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1957.tb05887.x

出版商:Blackwell Publishing Ltd    

年代:1957

数据来源: WILEY