title: Fruit photosynthesis in Satsuma mandarin.
abstract: To clarify detailed characteristics of fruit photosynthesis, possible gas exchange pathway and photosynthetic response to different environments were investigated in Satsuma mandarin (Citrus unshiu). About 300 mm(-2) stomata were present on fruit surface during young stages (∼10-30 mm diameter fruit) and each stoma increased in size until approximately 88 days after full bloom (DAFB), while the stomata collapsed steadily thereafter; more than 50% stomata deformed at 153 DAFB. The transpiration rate of the fruit appeared to match with stoma development and its intactness rather than the density. Gross photosynthetic rate of the rind increased gradually with increasing CO2 up to 500 ppm but decreased at higher concentrations, which may resemble C4 photosynthesis. In contrast, leaf photosynthesis increased constantly with CO2 increment. Although both fruit and leaf photosynthesis were accelerated by rising photosynthetic photon flux density (PPFD), fruit photosynthesis was greater under considerably lower PPFD from 13.5 to 68 μmolm(-2)s(-1). Thus, Satsuma mandarin fruit appears to incorporate CO2 through fully developed and non-collapsed stomata, and subject it to fruit photosynthesis, which may be characterized as intermediate status among C3, C4 and shade plant photosynthesis. The device of fruit photosynthesis may develop differently from its leaf to capture CO2 efficiently.
authors.affiliation: Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan. Electronic address: hiratuka@bio.mie-u.ac.jp.
authors.forename: Shin
authors.initials: S
authors.lastname: Hiratsuka
authors.affiliation: Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishimura
authors.affiliation: Graduate School of Bioresources, Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Nada
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002957:Citrus / Q000502:physiology*; D005638:Fruit / Q000378:metabolism; D017785:Photons; D010788:Photosynthesis; D054046:Plant Stomata / Q000378:metabolism; D018526:Plant Transpiration
chemical_list: D002245:Carbon Dioxide
keywords: CO(2) concentration; Citrus unshiu; Fruit Stoma; Fruit photosynthesis; Light intensity