Leaf surface wetness duration time is an important agrometeorological parameter that determines fungal infections and spread of plant diseases. Surface wetness could also contribute to the reduction of transpiration and enhance pesticide effectiveness. / For these reasons, field and laboratory performances of commonly used electrical resistance (ER) sensors were compared with a beta-ray gauge (BRG). The BRG provided the most accurate measure of surface wetness duration which agreed favourably with visual observations since it uses a real leaf as a sensor. A commercially available electric grid sensor (Model 237, Campbell Scientific), which employs a hard epoxy-fibreglass board, was found to be accurate in the determination of wetness duration for tobacco but not for soybean leaves. A second cotton cloth ER sensor was found to record accurately wetness duration on tobacco leaves. The data indicated that the choice of an ER sensor for best results depends on the density of the crop canopy. If accurate measurements of leaf surface wetness are critical it is suggested that the BRG system be used.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.61176 |
| Date | January 1991 |
| Creators | Armstrong, Robert |
| 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 Renewable Resources.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001276564, proquestno: AAIMM74850, Theses scanned by UMI/ProQuest. |
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