Effects of elevated CO2 concentration on bulbil germination and early seedling growth in Chinese yam under different air temperatures |
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| Authors: | Nguyen Cong Thinh Etsushi Kumagai Hiroyuki Shimono |
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| Institution: | 1. The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan;2. Agro-Environmental Research Division, NARO Tohoku Agricultural Research Center, Morioka, Japan |
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| Abstract: | The present study investigated the effects of elevated carbon dioxide concentration (CO2]) and air temperature on the germination of seed bulbils and the seedling vigour of two Chinese yam lines. Plants were grown under two CO2] levels, ambient and elevated (ambient + 200 μmol mol?1), and two mean air temperature regimes, 22.2 °C (ambient + 1.4 °C) and 25.6 °C (ambient + 5.2 °C). Elevated CO2] did not affect bulbil germination under both air temperature regimes. During the early growth stage, the dry weight (DW) of leaves, vines, shoots, roots, belowground parts (roots + tubers) and whole plants were higher under elevated CO2] than ambient CO2] for both lines under the low- and high-temperature regimes. The values of vigour indexes (index I = germination % × seedling length and index II = germination % × seedling DW) were also higher under elevated CO2] than ambient CO2] for both lines. These results indicated that Chinese yam seedlings respond positively to elevated CO2] during the early growth stage. The above:belowground DW ratios were lower under elevated CO2] than ambient CO2] in seedlings with very small new tubers for both yam lines, indicating that elevated CO2] strongly affected the root growth in the early growth stage. The DWs of post-treatment seed bulbils were higher in the elevated CO2] under both air temperature regimes. The results showed that Chinese yam used a smaller amount of the reserves in seed bulbils under elevated CO2] than under ambient CO2]. |
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| Keywords: | Chinese yam elevated CO2 germination rate nagaimo seedling growth |
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