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mitochondria electron transport inhibitors or METIs ( Ware and Whitacre, 2004 ; Yu, 2008 ). The mitochondrion (plural: mitochondria) is a membrane-bounded organelle that is associated with intracellular respiration. The mitochondrion is a major site of
., 2002 ), since this technique delivers information regarding the saturation characteristics of electron transport, as well as being able to quantify overall photosynthetic performance ( Ralph and Gademann, 2005 ). A clear effect of low light intensity
hydrogen (NADPH) via the electron transport chain, and a proton gradient across the thylakoid membrane drives adenosine triphosphate (ATP) synthase, regenerating ATP. These energy-rich molecules—NADPH and ATP—provide the reducing power and chemical energy
electron transfer between the primary and secondary quinones of PSII (see Abbaspoor et al., 2006 , and references cited therein). Interruption of photosynthetic electron transport inhibits adenosine 5′-triphosphate production and carbon fixation. If this
were the same as the first experiment for the PM and PA treatments, respectively. The experiment was conducted once. Chlorophyll content, the ratio of variable to maximum chlorophyll fluorescence (F v /F m ), and electron transport rate (ETR) were not
) and calculated using the formula of Moran (1982) . The ratio of variable to maximum chlorophyll fluorescence (F v /F m ) and electron transport rate (ETR) were measured and calculated with a Maxi-Imaging-PAM chlorophyll fluorescence measuring system
the membranes directly and affect the electron transport of chloroplasts and mitochondria, leading to the electron leakage and the generation of ROS ( Begović et al., 2016 ; Pazin et al., 2015 ; Pereira et al., 2013 ; Qiu et al., 2018 ). The
: soil amended with 5% or 10% (v/v) vermicompost. Fig. 6. Effect of vermicompost on spinach leaf photochemical efficiency (F v /F m ; A ), photochemical yield [Y(II); B ], and electron transport rate (ETR; C ) 35 d after transplanting. The values are
mean ± se (n = 3). Table 5. Maximum rate of carboxylation (V cmax ), maximum rate of electron transport at saturating irradiance (J max ), and CO 2 compensation point (CCP) of tung tree seedlings grown under different light treatments. Leaf anatomic
Photosystem II (PSII) efficiency and CO2 assimilation in response to photon flux density (PFD) and intercellular CO2 concentration (Ci) were monitored simultaneously in leaves of apple, pear, apricot, and cherry with a combined system for measuring chlorophyll fluorescence and gas exchange. When photorespiration was minimized by low O2 (2%) and saturated CO2 (1300 ppm), a linear relationship was found between PSII efficiency and the quantum yield for CO2 assimilation with altering PFD, indicating CO2 assimilation in this case is closely linked to PSII activity. As PFD increased from 80 to 1900 μmol·m–2·s–1 under ambient CO2 (350 ppm) and O2 (21%) conditions, PSII efficiency decreased by increased nonphotochemical quenching and decreased concentration of open PSII reaction centers. The rate of linear electron transport showed a similar response to PFD as CO2 assimilation. As Ci increased from 50 to 1000 ppm under saturating PFD (1000 μmol·m–2·s–1) and ambient O2, PSII efficiency was increased initially by decreased nonphotochemical quenching and increased concentration of open PSII reaction centers and then leveled off with further a rise in Ci. CO2 assimilation reached a plateau at a higher Ci than PSII efficiency because increasing Ci diverted electron flow from O2 reduction to CO2 assimilation by depressing photorespiration. It is concluded that PSII efficiency is regulated by both nonphotochemical quenching and concentration of open PSII reaction centers in response to light and CO2 to meet the requirement for photosynthetic electron transport.