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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nematodes, bacteria and their interrelationships in the crown-gall disease of tomatoes.

Chong, Kuang-Yin. January 1973 (has links)
No description available.
2

Some studies on the incidence of blothy ripening in greenhouse tomatoes in British Columbia

Matsumoto, Tsutomu January 1971 (has links)
Blotchy ripening (BR) of tomatoes is an irregular ripening of tomato fruits. This world-wide disorder has been a problem of the spring crop, particularly during the later part of May, in greenhouse tomatoes in British Columbia. For the investigation of the factors which affect the occurrence of BR in B.C., the following were considered: Correlation between the hours of bright sunshine and the incidence of BR, the influence of weekly alternation of light and temperature conditions on the incidence of BR, and the association of the incidence of BR and virus diseases. Examination of weather records led to a hypothesis which was tested in growth chambers. The light regimes employed consisted of a high and a low light condition. Concurrently two temperature regimes were used, one with a high maximum-temperature and the other with a low maximum temperature. Both regimes employed the same minimum temperature. The results of the studies were as follows: The cyclic occurrence of sunny weeks and cloudy weeks was associated with the incidence of BR in the B.C. greenhouse tomatoes. The weekly alternation of the light conditions produced 37% BR fruits when the plants were subjected to a constant day- night temperature cycle, but only 11% BR fruits, which was not significantly different from 6% BR in the control, was produced when the temperature conditions were alternated simultaneously and directly with light regimes. The role of tobacco mosaic virus (TMV) on the Incidence of BR in the B.C. greenhouse tomatoes did not appear to be important. The effect of potato virus (PVX) on the incidence of BR was not clear. / Land and Food Systems, Faculty of / Graduate
3

Post-harvest studies of a radiant energy-induced disorder of tomato fruits

Adegoroye, Adegoke Samuel January 1980 (has links)
Laboratory experiments and some field and greenhouse studies were carried out to determine the mode of action of radiant energy in the development of a post-harvest sunscald disorder of tomato (Lycopersicon esculentum Mill c.v.Vendor) fruits. The effects of the disorder on post-harvest fruit quality and physiology were evaluated by the physical determination of textural characteristics, the analysis of some chemical constituents and the measurement of fruit gas exchange. The ability of various storage temperatures, photoperiods and oxygen concentrations to alleviate injury was also examined. The effectiveness of radiant energy in causing sunscald injury was found to depend on the amount of radiant energy in the infra-red waveband. The action of infra-red radiation was thermal rather than photochemical. The use of high air temperatures to heat fruits produced symptoms similar to sunscald except that the colour of the fruit surface became greyish rather than white. Injury can develop at all stages of ripeness but symptoms vary with stage of ripeness. Injury also develops in light in the absence of oxygen or in darkness. Photooxidation does not appear to be a prerequisite for injury development. Injurious radiation treatments caused a loss of green colour and injured fruits failed to synthesize the red pigment; lycopene, in storage. Injury did not result in any appreciable loss in lycopene content once the pigment had formed. The mode of action of intense electromagnetic radiation on fruit colour therefore appears to be by destruction of the mechanism of carotenoid synthesis rather than by increased carotenoid degradation. Injury prevented protopectin solubilization during subsequent storage. It also led to a large reduction in ascorbic acid content and an increase in pH. The changes in ascorbic acid content and pH occurred progressively during the development of injury. Changes in the textural attributes of tomato fruits were assessed by measurements of six force-deformation characteristics: Deformation, Pericarp strength, Mesocarp resistance, Compliance, Firmness and Toughness. Toughness did not significantly change during ripeness. Although the effect of injury on Mesocarp resistance was not significant, the interaction of injury with storage was significant for the characteristic. Four characteristics: Pericarp strength, Mesocarp resistance, Compliance and Firmness were highly correlated with protopectin content. Of the textural indices, Compliance was the best predictor (R² = 90.4%; SŶ = 1.97) of protopectin content at different levels of injury, irrespective of ripeness or storage. It is therefore recommended that Compliance, rather than Firmness be used for detecting changes in the "softness" of tomato fruits. "Induction" and "incipient" types of injury accelerated the onset of the respiratory climacteric. "Advanced" type of injury reduced rates of respiration during fruit ripening. The failure of injured fruits to ripen normally was not due to lack of ethylene production since rates of ethylene production were high in injured fruits. The relationship between the respiratory climacteric and ethylene production was shifted by injury. Storage treatments involving different temperatures, photoperiods and oxygen concentrations did not alleviate injury. It is suggested that efforts aimed at controlling injury should emphasize prevention of exposure to radiation rather than attempt to cure injury in exposed fruit. / Land and Food Systems, Faculty of / Graduate
4

Presymptomatic detection of Fusarium wilt of tomato by electrical measurement as related to pectic enzyme production.

Caruso, Frank Lawrence 01 January 1974 (has links) (PDF)
No description available.
5

The external morphology of the tomato worm (Protoparce sexta Johan.; Lepidoptera: Sphingidae).

Madden, Archie Hugh 01 January 1939 (has links) (PDF)
No description available.
6

Nematodes, bacteria and their interrelationships in the crown-gall disease of tomatoes.

Chong, Kuang-Yin. January 1973 (has links)
No description available.
7

EFFECTS OF A SYSTEMIC NEMATICIDE ON THE DEVELOPMENT AND REPRODUCTION OF MELOIDOGYNE INCOGNITA

Levy, Zuleika Antunes da Silva, 1957- January 1986 (has links)
No description available.
8

Streak or winter blight of tomato in Quebec.

Vanterpool, Thomas C. January 1925 (has links)
No description available.
9

A study of the South African tomato curly stunt virus pathosystem: epidemiology, molecular diversity and resistance

07 November 2012 (has links)
PhD / In South Africa, tomato (Solanum /ycopersicum) is an important vegetable crop with considerable nutritional and economic value. Over the last decade, begomovirus (family Geminiviridae) infections associated with an upsurge of the whitefly vector, Bemisia tabaci, on tomato crops has become a serious threat to sustainable tomato production in South Africa. Begomovirus disease control in tomato is challenging and requires an integrated "pest" and "vector" management strategy, primarily based on the use of chemical and cultural practices aimed at reducing the virus vector as well as the use of resistant cultivars. Development of effective disease management practices for South Africa therefore requires detailed information on the complex vector-virus-host cropping system interactions. The aim of the study presented in this thesis was to investigate the South African whitefly vector/begomovirus/tomato-host pathosystem, with emphasis on the virus and vector diversity and distribution, and the identification of possible resistance sources. A survey of tomato-infecting begomoviruses was conducted during a six-year period (2006-2011 ). Techniques used to determine begomoviruses diversity included whole genome amplification using PCR, RCA (rolling circle amplification), conventional as well as next generation sequencing and development of a RCA-RFLP (restriction fragment length polymorphism) for rapid assessment of diversity. Sequence comparisons and phylogenetic analyses revealed the presence of three new monopartite begomovirus species, in addition to ToCSV, all of which belong to the African/South West Indian Ocean (SWIO) begomovirus clade. Recombination analysis indicated that all four tomato-infecting begomovirus species appear to be complex recombinants and suggests that they have evolved within the sub-Saharan Africa region, along with other African begomoviruses and that they are most likely indigenous to the region. Several weed species were also confirmed as symptomless begomovirus reservoirs, supporting their role in the emerging begomovirus epidemics in South Africa.
10

The physiology of tomato plants infected with root-knot nematode, Meloidogyne javanica

Meon, Sariah January 1978 (has links)
iii, 113 leaves : tables, graphs, photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1978

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