Pepper (Capsicum annuum L.), which originates from tropical environments is particularly sensitive to low temperatures. The Canadian climate, with its risks of cool temperatures during spring time, greatly limits the production of this temperature-sensitive crop. This work dealt with pepper plant exposure to low temperatures (9 and 15$ sp circ$C), at two early growth stages. 'Lady Bell' pepper plants were grown from seed under controlled conditions of 21$ sp circ$C, 50 $ pm$ 10% R.H., 16/8 light/dark cycle and 300 $ mu$molm$ sp{-2} / rm s sp{-1}$ PAR at the canopy level. Once plants had reached either the cotyledonary or the three-true-leaf stage low temperatures were applied. Treatment conditions lasted until plants had produced three additional leaves after which they were returned to the pretreatment conditions. Evaluations were made at six recognized developmental stages and included destructive measurements for growth analysis, pigment content and leaf anatomical features as well as weekly non-destructive measurements. Results showed that plant responses to 9 and 15$ sp circ$C were not the same when applied at the cotyledonary or the three-true-leaf stage. Overall growth decreased with decreasing temperatures and plants exposed to 9$ sp circ$C at the cotyledonary stage died. Plants exposed to cold treatments underwent a whole complex of changes in morphology which included reduction in leaf size, stem diameter, internode length and on leaf, branch and developing fruit abnormalities. Dry matter accumulation and distribution, leaf area production and leaf pigment levels varied with treatments. The anatomical changes which included alterations in epidermal and mesophyll cell dimensions and arrangement were reminiscent of a general response to a wide range of stress conditions reported for several other plant species. Upon return to the control temperature recovery was clearly observed especially in those plants exposed to the 15$ sp circ$C treatments. Plants ex
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.70184 |
| Date | January 1990 |
| Creators | Clavijo, Claret Michelangeli de |
| 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 | Doctor of Philosophy (Department of Plant Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001171914, proquestno: AAINN67594, Theses scanned by UMI/ProQuest. |
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