Two theories have been offered to explain the wilting symptoms displayed by plants attacked with vascular invading micro-organisms. These are the bundle plugging theory and the toxin theory. According to the former the movement of water through the water conducting vessels of the stem is hindered or even prevented by the clogging of the vessels with the pathogenic bacteria or fungi and other obstruction materials such as tyloses and gums formed under the stimulation of the pathogen. The proponents of the toxin theory claim that the wilting symptoms are due to toxins formed by the invading organisms or resulting from the interaction between host and parasite. Each of these theories is supported and weakened by experimental evidences. One approach to the solution of this problem is to study the effects of the disease upon certain aspects of the physiology of the host, such as transpiration, stomatal movement and photosynthesis. Many investigators working on diseases caused by wilt organisms have measured the transpiration course of the wilting plant. The methods used for these measurements vary a great deal and are very often specially adapted to the type of plant under observation, although the weighing method seems to have been most generally adopted. Weights are recorded daily or at different intervals during the day. To obtain more accurate frequent measurements of the water uptake is not necessary.[...]
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.123837 |
| Date | January 1949 |
| Creators | Coulombe, Louis-Joseph. |
| Contributors | Scarth, G. (Supervisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science. (Department of Plant Pathology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000591945, Theses scanned by McGill Library. |
Page generated in 0.001 seconds