Chlorophyll fluorometers Chlorophyll fluorescence

fluorescence image (ft value) of adaxial leaf surface

the development of fluorometers allowed chlorophyll fluorescence analysis become common method in plant research. chlorophyll fluorescence analysis has been revolutionized invention of pulse-amplitude-modulation (pam) technique , availability of first commercial modulated chlorophyll fluorometer pam-101 (walz, germany). modulating measuring light beam (microsecond-range pulses) , parallel detection of excited fluorescence relative fluorescence yield (ft) can determined in presence of ambient light. crucially, means chlorophyll fluorescence can measured in field in full sunlight.

today, chlorophyll fluorometers designed measuring many different plant mechanisms. measuring protocols: fv/fm , ojip measure efficiency of photosystem ii samples @ common , know dark adapted state. these protocols useful in measuring many types of plant stress. bernard genty’s light adapted measuring protocol Δf/fm’, or y(ii), effective , sensitive way measure plant samples under ambient or artificial lighting conditions. however, since y(ii) values change light intensity, 1 should compare samples @ same light intensity unless light stress focus of measurement. y(ii) can more sensitive types of plant stress fv/fm, such heat stress.

other plant mechanism measuring protocols have been developed. when chloroplast absorbs light, of light energy goes photochemistry, goes regulated heat dissipation, , goes unregulated heat dissipation. various chlorophyll fluorescence measuring parameters exist measure of these events. in lake model, ql measures photochemical quenching, y(nyo) measures plant regulated heat dissipation, , y(no) measures unregulated heat dissipation. older quenching protocol, called puddle model, uses qp photochemical quenching, qn nonphotochemical quenching of both regulated , unregulated heat dissipation , npq estimate of nonphotochemical quenching. npq has been resurrected lake model mathematically.

in addition, parameters qe, , pnpq have been developed measure photoprotective xanthophyll cycle. qt measure of state transitions. qm measure of chloroplast migration, , qi measure of plant photoinhibition.

at lower actinic light levels npq = qe+qt+qi

at high actinic light levels npq = qe+qm=qi

some fluorometers designed portable , operated in 1 hand.

consistent further development imaging fluorometers facilitate visualization of spatial heterogeneities in photosynthetic activity of samples. these heterogeneities naturally occur in plant leaves example during growths, various environmental stresses or pathogen infection. knowledge sample heterogeneities important correct interpretation of photosynthetic performance of plant sample. high performance imaging fluorometer systems provide options analyze single cell/single chloroplast sample areas covering whole leaves or plants.