This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Ku, S.-B. Articles by Tanner, C. B. Search for Related Content PubMed PubMed Citation Articles by Ku, S.-B. Articles by Tanner, C. B. Agricola Articles by Ku, S.-B. Articles by Tanner, C. B.

Articles

Effects of Light, Carbon Dioxide, and Temperature on Photosynthesis, Oxygen Inhibition of Photosynthesis, and Transpiration in Solanum tuberosum¹

^a Departments of Horticulture and Soil Science, University of Wisconsin, Madison, Wisconsin 53706

Individual leaves of potato (Solanum tuberosum L. W729R), a C₃ plant, were subjected to various irradiances (400-700 nm), CO₂ levels, and temperatures in a controlled-environment chamber. As irradiance increased, stomatal and mesophyll resistance exerted a strong and some-what paralleled regulation of photosynthesis as both showed a similar decrease reaching a minimum at about 85 neinsteins·cm^–2·sec^–1 (about of full sunlight). Also, there was a proportional hyperbolic increase in transpiration and photosynthesis with increasing irradiance up to 85 neinsteins·cm^–2·sec^–1. These results contrast with many C₃ plants that have a near full opening of stomata at much less light than is required for saturation of photosynthesis.

Inhibition of photosynthesis by 21% O₂ was nearly overcome by a 2-fold increase in atmospheric levels of CO₂ (about 1,200 ng·cm^–3). Photosynthesis at 25 C, high irradiance, 2.5% O₂ and atmospheric levels of CO₂ was about 80% of the CO₂-saturated rate, suggesting that CO₂ can be rate-limiting even without O₂ inhibition of photosynthesis. With increasing CO₂ concentration, mesophyll resistance decreased slightly while stomatal resistance increased markedly above 550 ng·cm^–3 which resulted in a significant reduction in transpiration.

Although potato is a very productive C₃ crop, there is substantial O₂ inhibition of photosynthesis. The level of O₂ inhibition was maximum around 25 C but the percentage inhibition of photosynthesis by O₂ increased steadily from 38% at 16 C to 56% at 36 C. Photosynthesis and transpiration showed broad temperature optima (16-25 C). At higher temperatures, both the increased percentage inhibition of photosynthesis by O₂ and the increased stomatal resistance limit photosynthesis, while increased stomatal resistance limits transpiration. Water use efficiency, when considered at a constant vapor pressure gradient, increased with increasing irradiance, CO₂ concentration, and temperature.

³ Department of soil Science.

¹ This research was supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison.