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

Additional integral and kinetic parameters of induction curves have been introduced on the basis of analysis of currently employed parameters of slow induction of fluorescence (SIF) for a more complete quantitative description of SIF changes during ontogenesis of higher plant leaves. High sensitivity of the additional parameters to the age state of leaf tissue as compared with previously employed parameters is demonstrated on the example of cucumber leaves (Cucumis sativus L.). Analysis of the relationship between the photosynthetic rate and SIF parameters of separate cucumber leaf disks revealed the presence of a high positive correlation between the photosynthetic rate and the greatest possible average decline in fluorescence intensity during the inductive period for mature regions of the leaf and regions starting to senesce (the correlation coeffcient attained values of 0.95), which indicates the possibility of using the given SIF parameter in further elaboration of methods for estimation of chloroplast photosynthetic activity at the level of the higher plant leaf.