Photosynthesis of Young Orchid Seedlings

Hew, C. S.; Khoo, S. I.

doi:10.1111/j.1469-8137.1980.tb01675.x

Cited by 13 publications

(9 citation statements)

References 18 publications

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“…6C). This suggests that younger Phalaenopsis plants may have a greater proportion of C 3 fi xation than older plants, as observed in several CAM species (Cushman et al, 1990;Hew and Khoo, 1980). TEMPERATURE.…”

Section: Resultsmentioning

confidence: 79%

Effect of Leaf and Plant Age, and Day/Night Temperature on Net CO2 Uptake in Phalaenopsis amabilis var. formosa

Guo¹,

Lee²

2006

jashs

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In this study, effects of leaf age (20 to 240 days), plant age (4, 8, and 14 months after deflasking), and various day/night temperature regimes (16 to 33 °C) on photosynthesis of Phalaenopsis amabilis L. Blume var. formosa Shimadzu (Phal. TS97) leaves were investigated. The diurnal net CO2 uptake in Phal. TS97 leaves was measured and integrated to obtain total net CO2 uptake, which represents photosynthetic efficiency in plants performing crassulacean acid metabolism (CAM). Under all conditions, Phal. TS97 leaves performed typical CAM photosynthesis and reached their highest net CO2 uptake rate, ≈6 μmol·m-2·s-1, after 3 to 4 hours in the dark under a 12-hour photoperiod. When grown under 30 °C day/25 °C night temperature, the total net CO2 uptake of leaf increased with maturation and was highest at 80 days old, 20 days after full expansion. The CAM photosynthetic capacity of mature leaves remained high after maturation and began to decline at a leaf age of 240 days. The trend was consistent with malate fixation but the highest nocturnal malate concentration was observed in 100-day-old leaves. Young leaves or leaves from small juvenile plants had higher daytime CO2 fixation compared to mature leaves or large plants, suggesting that Phal. TS97 leaves progressed from C3-CAM to CAM during the course of maturation. The second newly matured leaf from the top had the highest net CO2 fixation when the newest leaf was 8 cm in length. Although plant age did not influence total CO2 uptake in the leaf, photosynthetic efficiency of leaves in small younger plants was more sensitive to high light intensity, 340 μmol·m-2·s-1 photosynthetic photon flux. The day/night temperature of 32/28 and 29/25 °C resulted in the highest total net CAM CO2 fixation in vegetative Phal. TS97 plants than higher (33/29 °C) and lower temperatures (21/16 °C).

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Section: Resultsmentioning

confidence: 79%

Effect of Leaf and Plant Age, and Day/Night Temperature on Net CO2 Uptake in Phalaenopsis amabilis var. formosa

Guo¹,

Lee²

2006

jashs

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“…In vitro measurements of photosynthesis in protoplasts or cell suspensions obtained by enzymatic digestion of leaves of CAM plants generally exhibit no CAM activity. Very young leaves of CAM plants or experimentally convenient seedlings or small plantlets typically exhibit little or no detectable CAM activity (Hew and Khoo 1980;Dodd et al 2002;Lü ttge 2007). Recent imaging PAM studies by Lü ttge (2008) on Clusia minor show large variations in CAM activity within individual leaves.…”

Section: Introductionmentioning

confidence: 99%

The Use of Pulse Amplitude Modulation (PAM) Fluorometry to Measure Photosynthesis in a CAM Orchid, Dendrobium spp. (D. cv. Viravuth Pink)

Ritchie

Bunthawin

2010

International Journal of Plant Sciences

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Pulse amplitude modulation (PAM) fluorometer techniques provide unique information on photosynthetic activity of CAM (crassulacean acid metabolism) plants such as the orchid Dendrobium spp. (cv. Viravuth Pink). CAM plants close their stomata for at least part of the day, creating a sealed compartment in the stems and leaves that precludes measurement of the light reactions of photosynthesis by any gas exchange-based method. PAM machines calculate photosynthesis as the electron transport rate (ETR) through PSII (four electrons per O 2 produced) as mol m À2 s À1. Photosynthesis-versus-irradiance (P-vs.-E) curves fitted the waiting-in-line function (ETR ¼ ETR max 3 E=E opt À Á 3 e 1ÀE=Eopt), allowing half-saturating and optimal irradiances (E opt) to be estimated. Effective quantum yield (Y max), ETR (ETR max), and the nonphotochemical quenching parameter NPQ max all vary on a diurnal (circadian) cycle, but the parameter qN max does not show a systematic variation over a diurnal period. Dendrobium Viravuth is a ''sun plant,'' with E opt between 404 and 539 mmol m À2 s À1 PAR but photosynthetic capacity is very low in the late afternoon. Total CO 2 fixed nocturnally as C4-dicarboxylic acids by leaves was only %120 mg C m À2 d À1. Titratable acid of leaves was depleted by ;1500 hours and shows a classical CAM diurnal cycle. Dendrobium Viravuth stores only enough CO 2 as C4 acids to account for ;10% of the daily gross photosynthesis estimated with the PAM machine (%1.4 g C m À2 d À1). Dendrobium Viravuth is an orchid cultivar with very limited capacity to fix and store C4 acids at night. It is probably a CAM-cycling orchid.

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“…Smith et al, 1985). Although a few studies at least compared "young" and "adult" stages of the same species (Hew and Khoo, 1980;Adams andMartin, 1986a. 1986b), they failed to analyse possible continuous size-related changes in physiological parameters.…”

mentioning

confidence: 99%

Photosynthetic Capacity Increases with Plant Size

Zotz

1997

Botanica Acta

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The photosynthetic capacity of mature leaves of the epiphytic orchid, Dirnerondro ernarginoto. was studied in plants of different size. There was a linear increase of both area-based and dry weight-based rates of Orevolution with size by more than 100% from the smallest (1 cm tall) to the largest (50cm tall) individual. Similar size-related changes were observed in the leaf nitrogen content but not in the chlorophyll content. The results are discussed in the context of the optimal partitioning theory.

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Photosynthesis of Young Orchid Seedlings

Cited by 13 publications

References 18 publications

Effect of Leaf and Plant Age, and Day/Night Temperature on Net CO2 Uptake in Phalaenopsis amabilis var. formosa

Effect of Leaf and Plant Age, and Day/Night Temperature on Net CO2 Uptake in Phalaenopsis amabilis var. formosa

The Use of Pulse Amplitude Modulation (PAM) Fluorometry to Measure Photosynthesis in a CAM Orchid, Dendrobium spp. (D. cv. Viravuth Pink)

Photosynthetic Capacity Increases with Plant Size

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