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The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.)
Dissertation (MSc (Plant Sciences)--University of Pretoria, 2022.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2022
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| _version_ | 1867613451263672320 |
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| access_status_str | Open Access |
| author2 | Creux, Nicole |
| author_browse | Creux, Nicole |
| author_facet | Creux, Nicole |
| collection | Thesis |
| dc_rights_str_mv | © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Plant Sciences)--University of Pretoria, 2022. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/86253 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:36:21.406Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/86253 The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) Creux, Nicole uyabongeka.memela@up.ac.za Fourie, Gerda Memela, Uyabongeka UCTD Anthesis Heat wave Style elongation Stigma receptivity Pollen viability Natural and agricultural sciences theses SDG-02 Natural and agricultural sciences theses SDG-13 Natural and agricultural sciences theses SDG-15 Dissertation (MSc (Plant Sciences)--University of Pretoria, 2022. Anthesis and pollination are precisely timed events, which change with the surrounding environment depending on light, temperature, and humidity. Plants and pollinators may exhibit mismatched behaviors as a result of temperature changes, and relatively little information exists about how heat stress and heat waves affect anthesis and pollination in sunflowers (Helianthus Annuus L.). This study investigates the effect of heat stress on timing of pollen emergence, style elongation rate, pollinator visits, pollen viability and stigma receptivity. We sampled during the anthesis period in a field setting under different summer conditions, including sunny and overcast days each with artificially heated and unheated plants; and a natural heatwave. Sunflower insect visits were video imaged in all test conditions, and individual insects were counted. A variety of staining and imaging techniques were used to determine pollen fertility, style elongation, and stigma receptivity. Heating sunflower capitula to approximately 10°C above the natural temperature resulted in a faster rate of style elongation, earlier pollen emergence and reduced stigma receptivity. In both the sunny and overcast days, time-lapse images showed that pollen emergence was 15 minutes earlier on heated plants than unheated ones. Heatwaves, however, bring in significantly more early morning visitors than unheated sunny, which was not observed by artificial heating. At temperatures of 40°C on sunny days, stigma receptivity and pollen fertility appears to significantly decrease over time. Sunflowers are considered a robust and temperature hardy plant, which maintains yields even when subjected to harsh conditions. This is one of the first studies to assess the effect of heat stress on sunflower anthesis. Our findings suggest that even though sunflower anthesis and pollination can be negatively affected by the high temperatures associated with heatwave events, it is able to adapt and manage stress by changing timing of pollen emergence and insects visits to earlier in the day before the high temperatures can have their detrimental effect. SANSOR Oil and Protein Seed Development Trust CPHB (Centre of Excellence in Plant Health Biotechnology)/ TPCP (Tree Protection Co-operative Programme) DSI/NRF bs2026 Plant Production and Soil Science MSc (Plant Sciences) Unrestricted SDG-02: Zero hunger SDG-13: Climate action SDG-15: Life on land 2022-07-15T13:44:26Z 2022-07-15T13:44:26Z 2022-09 2022 Dissertation * S2022 https://repository.up.ac.za/handle/2263/86253 10.25403/UPresearchdata.20318943 en © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Anthesis Heat wave Style elongation Stigma receptivity Pollen viability Natural and agricultural sciences theses SDG-02 Natural and agricultural sciences theses SDG-13 Natural and agricultural sciences theses SDG-15 The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title | The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title_full | The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title_fullStr | The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title_full_unstemmed | The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title_short | The physiological effects of heat stress on anthesis and pollination in domesticated sunflowers (Helianthus annuus L.) |
| title_sort | physiological effects of heat stress on anthesis and pollination in domesticated sunflowers helianthus annuus l |
| topic | UCTD Anthesis Heat wave Style elongation Stigma receptivity Pollen viability Natural and agricultural sciences theses SDG-02 Natural and agricultural sciences theses SDG-13 Natural and agricultural sciences theses SDG-15 |
| url | https://repository.up.ac.za/handle/2263/86253 |