Leaf gas exchange and photosynthetic potential of pineapple (Ananas comosus L Merr) 'Smooth Cayenne'

Name: Pannee Chuennakorn

keyword: Carboxylation

LCSH: Kasetsart University -- Dissertations. Ph.D. (Agricultural Biotechnology) 2020

Classification :.LCCS: SB375

LCSH: Kasetsart University. -- Interdisciplinary Graduate Program -- Dissertations

LCSH: Pineappl -- Morphology

LCSH: Photosynthesis

Abstract: The magnitudes of leaf photosynthesis in pineapple ‘Smooth Cayenne’, a crassulacean acid metabolism (CAM) plant was elucidated by a combination measurement of leaf gas exchange, chlorophyll fluorescence and total acid content in open field condition. The 24–hour measurements were monitored each for the 3 seasons in Prachuap Khiri Khan. Leaf gas exchange displayed the four distinct carboxylation phases of CAM. Phase I was during dark period, net CO2 assimilation rate (A) increased with stomatal conductance (gs), having the maximal A in the low range of 2–2.6 µmolCO2 m–2 s–1, accompanied by the increase in total acid content (H+). The increment in A and H+ continued into Phase II during early morning which lasted about 2 hours when radiation (PPF) was still low. In this phase, photochemistry commenced showing an increase in electron transport rate (ETR), whereas H+ reached its maximum. Subsequent stronger PPF initiated Phase III, when A turned negative as gs reduced limiting external CO2 intake. On the other hand, ETR continued to increase to its maximum, enabling the decarboxylation of the accumulated acid. The acid decarboxylation rate (ADR), namely the CO2 carboxylation process was 6.7–7.8 µmolCO2 m–2 s–1. Phase III lasted 6–8 hours ending in late afternoon, as H+ was mostly spent and ADR dropped closed to zero. In pineapple, Phase IV clearly appeared when gs increased (stomata reopening) and positive A was detected. The different extents of Phase IV among seasons illustrated the most plasticity of CAM photosynthesis capacity. In full cycle, 80% of substrate CO2 in the form of acid was acquired during dark period, making pineapple a strong CAM plant. The net daily CO2 gain was 47.0–51.6 mmolCO2 m–2 in summer and winter, which was almost 3 times greater than in rainy season. The stomatal opening in dark period seemed to be controlled by the level of relative humidity (RH) which had to reach 70%. Light response function was assessed for each carboxylation phase. The results indicated that ‘Smooth Cayenne’ pineapple as a CAM plant has a high photosynthetic capacity. Significantly, the highest level of photochemistry took place in the first part of Phase III when leaf obtained adequate PPF and internal CO2 released from the highest accumulated acid content. ETR was maximum at 143 µmol e- m–2 s–1, yielding a gross photosynthesis rate (Pg) of 35.8 µmolCO2 m–2 s–1 and the light saturation (Is ETR) of 750 µmolPPF m–2 s–1

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Suntaree Yingjajaval

Role: Thesis Advisor

Created: 2020

Modified: 2025-07-02

Issued: 2025-07-02

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2563/pannee-chu-all.pdf

CallNumber: SB375 .P36

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degraee

Descipline: Agricultural Biotechnology

Grantor: Kasetsart University

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