摘要:

The prophylactic effect resulting from the localized application of streptomycin as a foliage spray on dwarf bean plants has been examined. Streptomycin sulphate solution applied to the primary leaves exhibited a marked and consistent systemic, antibacterial, prophylactic action even at sites as far removed from the point of application as the fourth trifoliate leaf. This systemic protection against the halo blight organism persisted for various periods up to a maximum of 11 days. Mannosidostreptomycin was much inferior to streptomycin in its systemic prophylactic action against halo blight.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06853.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

The growthin vitroofBacterium carotovorumf.zeaeSabet, the cause of the root and stalk rot and leaf blight disease of maize, was inhibited by dihydrostreptiomycin sulphate and by Terramycin (oxytetracycline). Joint applications showed a synergistic action, and the bacterium was most susceptible to a 1:1 mixture of the two antibiotics. This mixture is effective in checking the development of resistant strains which develop rapidly after treatment with streptomycin alone.Roots of maize seedlings in water cultures, and leaves of older plants readily absorb both antibiotics. High water content of soil favoured absorption; sunlight had no effect. Absorption from leaf applications first increased with higher concentration and frequency of spraying, but after eight daily applications of streptomycin toxic symptoms appeared and there was evidence that the antibiotic was inactivated.Antibiotic treatment of maize leaves shortly before inoculation withB. carotovorumf.zeaereduced the incidence and severity of leaf blight. The therapeutic effect extends at first both downward and upward but later only upward. Treatment of the leaves did not induce resistance to infection in the stems and roots.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06854.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Viruses that are transmitted by white‐fly occur commonly in solanaceous and malvaceous species, and infected plants from both families often exhibit similar kinds of symptoms. Consequently it has often been assumed that the same viruses infect species in both families, although attempts to demonstrate this experimentally have all failed. Now, however, usingBemisia tabaci(Genn.), we have transmitted the infectious chlorosis virus of Malvaceae fromSida rhombifoliatoNicandra physaloides. Bemisia tabacialso transmitted the virus from infectedNicandra physaloidesto healthy seedlings of bothN. physaloidesandSida rhombifolia.Attempts to infectNicotiana tabacumfaile

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06855.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Individual tillers of timothy (Phleum pratense) growing from seed in pots were labelled and their life history studied over a period of two years.The leaf axil position of the first‐produced tiller depended on its time of origin. A minimum of five leaves on the parent axis was necessary before its appearance, and no tiller emerged from the axil of any of the three terminal leaves of a shoot.Ear‐bearing capacity was high in early‐formed tillers, but decreased progressively with later dates of origin despite favourable day length; all tillers arising after the end of July failed to produce inflorescences. A greater proportion of tillers on the main stem formed ears than secondary tillers of the same age. Time of ear emergence varied only within a few days for all tillers arising before the end of April. The number of leaves formed up to ear emergence varied linearly with date of origin and tiller position, the lowest recorded number being six.Dry weight and length of inflorescence as well as seed yield per tiller varied linearly with the date of origin of tillers. Primary tillers generally had longer and heavier inflorescences and produced more seed per stem than secondary tillers of the same age.Tillers arising at all times were found to have a limited span of life, not normally exceeding just over a year. The mean age of ear‐bearing tillers varied linearly with their date of origin. Death‐rates of all tillers generally increased with their age. Relative death‐rates of fertile and vegetative tillers rose rapidly in the autumn but decreased during winter and early spring. Vegetative tillers which elongated in the year of formation survived for a shorter time than equivalent tillers in which stem elongation was delayed until the following year.The perennial habit of grasses is discussed in relation to tiller survival. Successive new formation and death of tillers keep the plant in a condition of continuous dyn

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06856.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

An apparatus is described which gives a controlled daily cycle of temperature. The hand of a 24 hr. clock is connected by a rod to the arm operating a thermostat contact and moves the contact slowly backwards and forwards. Its method of use is described and the shape of curve it produces is expressed as a mathematical formula. A method of obtaining a nearly constant relative humidity is described.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06857.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06858.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06860.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Book reviewed in this article:Biological Specificity and Growth(the 12th Symposium of the Society for the Study of Development and Growth). Ed. by E. G. ButlerThe Cultivation of Animal and Plant Cells.By PhilipR. WhiteAuxins and Plant GrowthBy A. CarlLeopoldCotton Growing Problems.By B. G. Christidisand G. J. HarrisonEvolution of the Vertebrates.By EdwinH. Colbert

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1956.tb06861.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY