QUANTITATIVE DESCRIPTION OF SLOW INDUCTION OF CHLOROPHYLL FLUORESCENCE DURING ONTOGENY OF HIGHER-PLANT LEAVES

Additional integral and kinetic parameters of induction curves have be en introduced on the basis of analysis of currently employed parameter s of slow induction of fluorescence (SIF) for a more complete quantita tive description of SIF changes during ontogenesis of higher plant lea ves. High sensitivity of the additional parameters to the age state of leaf tissue as compared with previously employed parameters is demons trated on the example of cucumber leaves (Cucumis sativus L.). Analysi s of the relationship between the photosynthetic rate and SIF paramete rs of separate cucumber leaf disks revealed the presence of a high pos itive correlation between the photosynthetic rate and the greatest pos sible average decline in fluorescence intensity during the inductive p eriod for mature regions of the leaf and regions starting to senesce ( the correlation coeffcient attained values of 0.95), which indicates t he possibility of using the given SIF parameter in further elaboration of methods for estimation of chloroplast photosynthetic activity at t he level of the higher plant leaf.