Photosynthetic pigments,morphology and leaf gas exchange during ex vitro acclimatization of micropropagated CAM Doritaenopsis plantlets under relative humidity and air temperature |
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| Institution: | 1. College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian 271018, China;2. Department of Horticulture, ALS 4017, Oregon State University, Corvallis, OR 97331, USA;1. Centro de Edafología y Biología Aplicada del Segura, CSIC, Campus Universitario de Espinardo, PO Box 164, 30100 Murcia, Spain;2. Instituto Agroforestal Mediterráneo, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain;1. College of Forestry, Nanjing Forestry University, Nanjing, China;2. Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China;3. Anhui Green and Selenium Technology Development Company in Agriculture and Ecology, Shitai, China;1. Department of Horticultural Science, School of Agriculture, Shiraz University, Shiraz, Iran;2. Drought Research Center, School of Agriculture, Shiraz University, Shiraz, Iran;3. Department of Horticulture, College of Aburaihan, University of Tehran, Pakdasht, Tehran, Iran;1. Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Denmark;2. Department of Agroecology, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark;3. Sino-Danish Center for Education and Research (SDC), Beijing, China |
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| Abstract: | The effect of relative humidity (RH) and temperature on CO2 assimilation (An), stomatal conductance (Sc), transpiration rate (Tr), chlorophyll content, fresh and dry weight, leaf length, leaf area, leaf width, formation of new root and survival rate have been assayed in Doritaenopsis in growth chamber after 1 month of acclimatization. Reduced growth was observed at below and above 25 °C whereas it was increased with increasing humidity. Relative water content (RWC) was decreased at 50% and 70% humidity after second day of transfer and recovered completely with the progression of acclimatization. RWC also reduced at high temperature but recovered slowly and a gradual decrease of RWC was observed at 15 °C. A visual symptom of severe leaf tip burn was observed at 50–70% humidity and at 35 °C during acclimatization. At 15 °C and 50% humidity sudden decrease of photosynthetic efficiency (Fv/Fm) was observed, which could not recover in temperature treated plantlets during acclimatization period. Chlorophyll content increased with increasing humidity and at 15 and 35 °C chlorophyll content was decreased compared to 25 °C. Chlorophyll a/b ratio was unchanged while total chlorophyll/carotenoids ratio was increased from low to high temperature. Exposure of plantlets to high temperature led to a noticeable decrease in An, Sc and Tr, and at 15 °C they were more decreased whereas significant differences were not observed in the parameters tested under humidity after 25 days of acclimatization. During daytime at 15 °C, increase in An, Sc and Tr indicates the plantlets adaptability in the new environment. The peroxidase activity remained unaffected in all humidity stress whereas low temperature increased the peroxidase activity compared to high temperature. These finding suggests that photosynthetic properties was greatly affected by air temperature conditions with a reduction of An, Sc and Tr at 15 and 35 °C compared to humidity stress that played a greater role in limiting photosynthesis. |
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