Applications of the Theory Chlorophyll fluorescence

1 applications of theory

1.1 psii yield measure of photosynthesis
1.2 relating electron transport carbon fixation
1.3 measuring stress , stress tolerance
1.4 nitrogen balance index
1.5 measure chlorophyll content

applications of theory
psii yield measure of photosynthesis

chlorophyll fluorescence appears measure of photosynthesis, over-simplification. fluorescence can measure efficiency of psii photochemistry, can used estimate rate of linear electron transport multiplying light intensity. however, researchers mean carbon fixation when refer photosynthesis. electron transport , co2 fixation can correlate well, may not correlate in field due processes such photorespiration, nitrogen metabolism , mehler reaction.

relating electron transport carbon fixation

a powerful research technique simultaneously measure chlorophyll fluorescence , gas exchange obtain full picture of response of plants environment. 1 technique simultaneously measure co2 fixation , psii photochemistry @ different light intensities, in non-photorespiratory conditions. plot of co2 fixation , psii photochemistry indicates electron requirement per molecule co2 fixed. estimation, extent of photorespiration may estimated. has been used explore significance of photorespiration photoprotective mechanism during drought.

fluorescence analysis can applied understanding effects of low , high temperatures.

sobrado (2008) investigated gas exchange , chlorophyll fluorescence responses high intensity light, of pioneer species , forest species. midday leaf gas exchange measured using photosynthesis system, measured net photosynthetic rate, gs, , intercellular co2 concentration (




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). in same leaves used gas exchange measurements, chlorophyll fluorescence parameters (initial,





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; maximum,





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; , variable,





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) measured using fluorometer. results showed despite pioneer species , forest species occupying different habitats, both showed similar vulnerability midday photoinhibition in sun-exposed leaves.

measuring stress , stress tolerance

chlorophyll fluorescence can measure types of plant stress. chlorophyll fluorescence can used proxy of plant stress because environmental stresses, e.g. extremes of temperature, light , water availability, can reduce ability of plant metabolise normally. can mean imbalance between absorption of light energy chlorophyll , use of energy in photosynthesis.

favaretto et al. (2010) investigated adaptation strong light environment in pioneer , late successional species, grown under 100% , 10% light. numerous parameters, including chlorophyll fluorescence, measured. greater decline in







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under full sun light in late-successional species in pioneer species observed. overall, results show pioneer species perform better under high-sun light late- successional species, suggesting pioneer plants have more potential tolerance photo-oxidative damage.


neocleous , vasilakakis (2009) investigated response of raspberry boron , salt stress. chlorophyll fluorometer used measure





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,





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. leaf chlorophyll fluorescence not affected nacl concentration when b concentration low. when b increased, leaf chlorophyll fluorescence reduced under saline conditions. concluded combined effect of b , nacl on raspberries induces toxic effect in photochemical parameters.
lu , zhang (1999) studied heat stress in wheat plants , found temperature stability in photosystem ii of water-stressed leaves correlates positively resistance in metabolism during photosynthesis.

nitrogen balance index

example of portable multiparametric fluorometer uses ratio between chlorophyll , flavonols detect nitrogen deficiency of plants

because of link between chlorophyll content , nitrogen content in leaves, chlorophyll fluorometers can used detect nitrogen deficiency in plants, several methods.

based on several years of research , experimentation, polyphenols can indicators of nitrogen status of plant. instance, when plant under optimal conditions, favours primary metabolism , synthesises proteins (nitrogen molecules) containing chlorophyll, , few flavonols (carbon-based secondary compounds). on other hand, in case of lack of nitrogen, observe increased production of flavonols plant.

the nbi (nitrogen balance index) force-a, allows assessment of nitrogen conditions of culture calculating ratio between chlorophyll , flavonols (related nitrogen/carbon allocation) .

measure chlorophyll content

gitelson (1999) states, ratio between chlorophyll fluorescence @ 735 nm , wavelength range 700nm 710 nm, f735/f700 found linearly proportional chlorophyll content (with determination coefficient, r2, more 0.95) , ratio can used precise indicator of chlorophyll content in plant leaves.