ISHS Acta Horticulturae 440: International Symposium on Plant Production in Closed Ecosystems
OPTIMUM AND SUB-OPTIMAL TEMPERATURE EFFECTS ON STOMATA AND PHOTOSYNTHESIS RATE OF DETERMINATE SOYBEANS |
| Authors: | A.K. Ghosh, M. Ichii, K. Asanuma, A. Kusutani |
| Keywords: | Glycine max L. Merr., optimum temperature, photosynthesis, soybean, stomatal activity, stomatal frequency, sub-optimum temperature |
| DOI: | 10.17660/ActaHortic.1996.440.15 |
| Abstract:
Stomatal frequency, length and width were studied in two determinate type soybean (Glycine max L. Merr.) cultivars at 15, 20 and 25 °C on 60th day after emergence. The stomatal frequency on the adaxial leaf surface did not show any consistent trend for the increase of growing temperatures but on the abaxial surface, stomatal frequency significantly decreased for every increase of 5 °C. Akishirome had 503, 454 and 379 stomata mm-2 and Akiyoshi had 471, 442 and 384 mm-2 at 15, 20 and 25 °C respectively. The stomatal lengths of both surfaces increased toward optimum temperature and were longer in the adaxial surface. Maintaining this trend, the lengths varied between 16.3 to 23.4 μm on the adaxial surface and from 14.2 to 21.5 μm on the abaxial surface. Width of the whole stomatal apparatus at noon time did not show any significant variation due to environmental temperature. Net photosynthesis rate of 4th leaf from top significantly increased in higher temperatures in both cultivars and showed similar trend at 32nd day after emergence and on 62nd day after emergence. Stomatal conductance increased and dark respiration decreased with increasing temperature. Plants grown in 25 °C were transferred to 15, 20 and 30 °C temperature chambers. On the 30th day after emergence, 4 hours of treatment resulted similar significant effects on net photosynthesis (ranging between 12.55 and 31.37 μmole CO2m-2 s-1 in Akishirome, and between 16.26 to 34.53 μmole CO2 m-2 s-1 in Akiyoshi). 72 hours of similar treatments at 60 day after emergence also produced identical results. Therefore, higher temperature increased stomatal size but decreased its frequency, and increased net photosynthesis and stomatal conductance. | |
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