Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats
Four evergreen broadleaf <i>Rhododendron</i> spp. (<i>Rhododendrons</i>), namely, <i>Rhododendron aganniphum</i>, <i>R. nyingchiense</i>, <i>R. wardii</i>, and <i>R. triflorum</i>, occur in harsh subalpine habitats in the southw...
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| Language: | English |
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MDPI AG
2022-04-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/13/5/653 |
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| author | Huie Li Qiqiang Guo Lan Yang Hong Quan Shuli Wang |
| author_facet | Huie Li Qiqiang Guo Lan Yang Hong Quan Shuli Wang |
| author_sort | Huie Li |
| collection | DOAJ |
| description | Four evergreen broadleaf <i>Rhododendron</i> spp. (<i>Rhododendrons</i>), namely, <i>Rhododendron aganniphum</i>, <i>R. nyingchiense</i>, <i>R. wardii</i>, and <i>R. triflorum</i>, occur in harsh subalpine habitats in the southwest Qinghai-Tibet Plateau (QTP), China. Considering that the four <i>Rhododendrons</i> cannot escape their unique environment, they must evolve a set of adaptations to survive, but the information is lacking. To uncover their physiological adaptation characteristics, in the present study, we monitored their physiological characteristics by determination of their seasonal variation in antioxidant enzyme activity, osmotic adjustment substrates, and carbohydrate contents, and their pigment content and photosynthetic efficiency. The results showed that superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities and proline content of four <i>Rhododendrons</i> had a significant difference in autumn and were insignificant in summer. Specifically, <i>R. aganniphum</i> had the maximum protective enzyme activity and proline content in winter as well as chl a, b, and car contents. The values of maximal quantum yield (<i>Fv</i>/<i>Fm</i>), photochemical efficiency (ΦPSII), and non-photochemical quenching (NPQ) of four <i>Rhododendrons</i> were significantly higher in summer than in other seasons. The lower qP indicated the four <i>Rhododendrons</i> were susceptible to photoinhibition. Overall, the four <i>Rhododendrons</i> had similar physical characteristics in subalpine habitats. The parameters of the maximum quantum yield of photosystem II (PSII), the actual quantum yield of PSII, the non-photochemical chlorophyll fluorescence quenching, and chlorophyll a content increased in summer. Meanwhile, the protective enzyme activity and total soluble sugar content, proline content, and carotenoid content increased in spring, autumn, and winter. These results suggested that the four <i>Rhododendrons</i> can adapt to subalpine habitats by heat dissipation to avoid the damage of excessive radiation during the warm season while scavenging reactive oxygen and increasing the intracellular fluid concentration to avoid damage caused by chilling temperatures during the cold seasons. These findings would provide a reference for the conservation and application of these valuable ornamental evergreen broadleaf <i>Rhododendrons</i>, and enrich theory of plant eco-physiology in the high altitudes of the QTP. |
| first_indexed | 2024-03-10T03:53:27Z |
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| id | doaj.art-a865f4b9b2c5417bb499d1f4f8c3f1bf |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-10T03:53:27Z |
| publishDate | 2022-04-01 |
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| series | Forests |
| spelling | doaj.art-a865f4b9b2c5417bb499d1f4f8c3f1bf2023-11-23T11:00:47ZengMDPI AGForests1999-49072022-04-0113565310.3390/f13050653Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine HabitatsHuie Li0Qiqiang Guo1Lan Yang2Hong Quan3Shuli Wang4College of Agriculture, Guizhou University, Guiyang 550025, ChinaInstitute for Forest Resources & Environment of Guizhou, Guizhou University, Guiyang 550025, ChinaCollege of Agriculture, Guizhou University, Guiyang 550025, ChinaKey Laboratory of Forest Ecology in Tibet Plateau, Institute of Tibet Plateau Ecology, Ministry of Education, Tibet Agriculture and Husbandry University, Nyingchi 860000, ChinaKey Laboratory of Forest Ecology in Tibet Plateau, Institute of Tibet Plateau Ecology, Ministry of Education, Tibet Agriculture and Husbandry University, Nyingchi 860000, ChinaFour evergreen broadleaf <i>Rhododendron</i> spp. (<i>Rhododendrons</i>), namely, <i>Rhododendron aganniphum</i>, <i>R. nyingchiense</i>, <i>R. wardii</i>, and <i>R. triflorum</i>, occur in harsh subalpine habitats in the southwest Qinghai-Tibet Plateau (QTP), China. Considering that the four <i>Rhododendrons</i> cannot escape their unique environment, they must evolve a set of adaptations to survive, but the information is lacking. To uncover their physiological adaptation characteristics, in the present study, we monitored their physiological characteristics by determination of their seasonal variation in antioxidant enzyme activity, osmotic adjustment substrates, and carbohydrate contents, and their pigment content and photosynthetic efficiency. The results showed that superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities and proline content of four <i>Rhododendrons</i> had a significant difference in autumn and were insignificant in summer. Specifically, <i>R. aganniphum</i> had the maximum protective enzyme activity and proline content in winter as well as chl a, b, and car contents. The values of maximal quantum yield (<i>Fv</i>/<i>Fm</i>), photochemical efficiency (ΦPSII), and non-photochemical quenching (NPQ) of four <i>Rhododendrons</i> were significantly higher in summer than in other seasons. The lower qP indicated the four <i>Rhododendrons</i> were susceptible to photoinhibition. Overall, the four <i>Rhododendrons</i> had similar physical characteristics in subalpine habitats. The parameters of the maximum quantum yield of photosystem II (PSII), the actual quantum yield of PSII, the non-photochemical chlorophyll fluorescence quenching, and chlorophyll a content increased in summer. Meanwhile, the protective enzyme activity and total soluble sugar content, proline content, and carotenoid content increased in spring, autumn, and winter. These results suggested that the four <i>Rhododendrons</i> can adapt to subalpine habitats by heat dissipation to avoid the damage of excessive radiation during the warm season while scavenging reactive oxygen and increasing the intracellular fluid concentration to avoid damage caused by chilling temperatures during the cold seasons. These findings would provide a reference for the conservation and application of these valuable ornamental evergreen broadleaf <i>Rhododendrons</i>, and enrich theory of plant eco-physiology in the high altitudes of the QTP.https://www.mdpi.com/1999-4907/13/5/653<i>Rhododendron</i>physiological characteristicsphotosynthetic efficiencyprotective enzymesosmotic adjustment substratespigment content |
| spellingShingle | Huie Li Qiqiang Guo Lan Yang Hong Quan Shuli Wang Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats Forests <i>Rhododendron</i> physiological characteristics photosynthetic efficiency protective enzymes osmotic adjustment substrates pigment content |
| title | Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats |
| title_full | Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats |
| title_fullStr | Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats |
| title_full_unstemmed | Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats |
| title_short | Seasonal Eco-Physiology Characteristics of Four Evergreen <i>Rhododendron</i> Species to the Subalpine Habitats |
| title_sort | seasonal eco physiology characteristics of four evergreen i rhododendron i species to the subalpine habitats |
| topic | <i>Rhododendron</i> physiological characteristics photosynthetic efficiency protective enzymes osmotic adjustment substrates pigment content |
| url | https://www.mdpi.com/1999-4907/13/5/653 |
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