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Sandra B. Wilson, Jeongwook Heo, Chieri Kubota and Toyoki Kozai

Sweetpotato [Ipomoea batatas (L.) Lam., `Beniazuma'] plantlets were grown photoautotrophically (without sugar) for 12 days in an improved forced ventilation system designed with air distribution pipes for uniform spatial distributions of carbon dioxide (CO2) concentration. Enriched CO2 conditions and photosynthetic photon flux (PPF) were provided at 1500 μmol·mol-1 and 150 μmol·m-2·s-1, respectively. The forced (F) ventilation treatments were designated high (FH), medium (FM), and low (FL), corresponding to ventilation rates of 23 mL·s-1 (1.40 inch3/s), 17 mL·s-1 (1.04 inch3/s), and 10 mL·s-1 (0.61 inch3/s), respectively, on day 12. The natural (N) ventilation treatment was extremely low (NE) at 0.4 mL·s-1 (0.02 inch3/s), relative to the forced ventilation treatments. Total soluble sugar (TSS) and starch content were determined on day 12. Total soluble sugars (sucrose, glucose, fructose) of FH plantlets were lowest in leaf tissue and highest in stem tissue as compared to other ventilation treatments. Starch concentration was higher in leaf tissue of FH or FM plantlets as compared to that of FL or NE plantlets. Plantlets subjected to FH or FM treatments exhibited significantly higher net photosynthetic rates (NPR) than those of the other treatments; and on day 12, NPR was almost five times higher in the FH or FM treatment than the FL or NE treatments. Carbohydrate concentration of plantlets was also influenced by the position of the plantlets in the vessel. Within the forced ventilation vessels, leaf TSS of FH and FM plantlets was similar regardless of whether plantlets were located near the inlet or outlet of CO2 enriched air. However, under FH or FM conditions, leaf starch concentration was higher in plantlets located closest to the CO2 inlet as compared to the outlet.

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Carl-Otto Ottosen

Abbreviations: C I , internal CO 2 concentration (ppm CO 2 ); G 5 , stomatal conductance (mol·s -1 ·m -2 ); P N , net photosynthetic rate (μmol CO 2 /sec per square meter); T, transpiration rate (μmol H 2 O/sec per square meter). 1 Former Research

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Youping Sun, Sarah A. White, David Mann and Jeffrey Adelberg

-controlled growth room at 23 °C. Vertical bars represent the sem response of n = 8 plants for the 30 and 60 d chilling treatments and n = 10 plants for the 90, 120, 150, and 180 d chilling treatments. The potential net photosynthetic rates of V. californicum

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Tongyin Li, Guihong Bi, Richard L. Harkess, Geoffrey C. Denny and Carolyn Scagel

a specific plant. Photosynthetic measurements. Leaf net photosynthetic rate and g S of hydrangea plants were measured between 1000 and 1300 hr on 27 Aug., 11 Sept., 22 Sept., and 8 Oct. 2014 using a portable photosynthesis system (LI-6400XT; LI

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Ming Ding, Beibei Bie, Wu Jiang, Qingqing Duan, Hongmei Du and Danfeng Huang

, Fv/Fm (ratio of variable to the maximal chlorophyll fluorescence) using a pulse-modulated fluorometer (Model OS1-FL; Opti-Sciences, Hudson, NH) after 30 min dark adaptation. Net photosynthetic rate and g S of watermelon seedlings after transplanting

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Timothy L. Righetti, Carmo Vasconcelos, David R. Sandrock, Samuel Ortega-Farias, Yerko Moreno and Francisco J. Meza

; Righetti et al., 2007 ; Tanner, 1949 ) were evaluated to demonstrate how ratio-based assessments of CO 2 assimilation are strongly dependent on leaf size. Net photosynthetic rates (μmol·m −2 ·s −1 ) are usually expressed on a leaf-area basis. When we

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Jiangbo Dang, Tingrong Wu, Guolu Liang, Di Wu, Qiao He and Qigao Guo

in unit area (cm 2 ) and unit mass (g) were calculated based on formulas presented by Lichtenthaler (1987) . Net photosynthetic rate measurements. Net photosynthetic rates of adult trees and the scions on the grafted seedlings were measured with

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Hans Spalholz and Chieri Kubota

) showed that ‘Zaojia 84–24’ watermelon seedlings grafted onto ‘Zhuangshi’ squash ( C. moschata ) rootstock retained higher chlorophyll and soluble sugar during storage and exhibited higher net photosynthetic rate during the poststorage recovery than

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Ben Hong Wu, Hai Qiang Huang, Pei Ge Fan, Shao Hua Li and Guo Jie Liu

et al., 2004 ). Li et al. (2005) reported that fruit removal resulted in a 50% to 56% reduction in net photosynthetic rate in ‘Okubo’ peach and a 22% to 39% reduction in ‘Yanfeng 1’ peach, compared with fruit-bearing shoots. However, this effect of

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Weijie Jiang, Jie Bai, Xueyong Yang, Hongjun Yu and Yanpeng Liu

replications, and means were compared with Duncan's multiple range test ( P < 0.05) analyzed by SAS (version 8.0). Results The effects of PGRs on leaf net photosynthetic rate under suboptimal temperature stress. As shown in Fig. 1 , under normal conditions