Summary:
The influence of pyrazon. norflurazon and glyphosate on post‐luminescence decay and fluorescence emission was studied. Pyrazon and norflurazon significantly increased post‐luminescence decay in wheat (Triticum vulgare L) and cuckoo flower (Cardamine pratensis L.). Pyrazon was much more active than norflurazon m this respect, No influence of’glyphosate on post‐luminescence and the emission ol” fluorescence was observed.
Measurements of post‐luminescence decay and fluorescence emission can serve to define some aspects of herbicidal pbyto‐toxicity and provide information on the initial action of those compounds that inhibit photosynthesis.
The effect of the organometallic compounds containing lead, (C6H5)3PbCl , and tin, (C6H5)3SnCl, on Chlorella green algae photosystem II was studied. Suspension of the algae treated with (C6H5)3SnCl at concentrations of 1.0 and 4.0 micromol dm(-3) for 22 h revealed a decrease in most physiological parameters studied, particularly in decasecond component of delayed chlorophyll luminescence, photosynthetic electron transport rate and diluted oxygen concentration, which implies an inhibition of photosynthetic electron transport as well as oxygen evolving system. On the other hand, (C6H5)3PbCl caused stronger inhibition than (C6H5)3SnCl, particularly in the higher concentration.
) at light on cucumber and peppermint leaves were studied. A considerable decrease of the most important chlorophyll fluorescence parameters values mainly in the cucumber leaves, compared to the control, was observed. It indicates damages as well as at a donor and acceptor side of photosystem II, specially in the oxygen evolving complex, electron transport and connected with the dark reactions. In the peppermint leaves these values were unchanged or slight decreased. After 24 h from disappearing of the applied UV-B stress, adverse changes became established, especially in the cucumber leaves show irreversible damages of photosystem II. Coefficient of nonphotochemical quenching increased by 50% in the peppermint leaves, while in cucumber remained unchanged. Chlorophyll delayed luminescence coefficient was decreased by 36% in the UV-B irradiated cucumber leaves and by 25% in the peppermint leaves. Content of ultraviolet-absorbing compounds was higher in peppermint leaves by 78% than in the cucumber. Generally, peppermint seemed to be more tolerant to the applied UV-B radiation compared to cucumber. K e y w o r d s: ultraviolet-B, leaves, cucumber, peppermint, photosynthesis reactions
The parameters of chlorophyll a fluorescence induction were measured: Fv/Fm, Sc/Fm, Rfd and coefficient of Ld delayed luminescence decay kinetics, related with a course of primary photosynthesis reactions on leaves of strawberry plants, cultured in vitro by means of the micropropagation methods. Strawberry plants cv. Ananasowa from in vitro cultures in optimal condition show significantly higher values of luminescence parameters indicating better condition of plants of this variety in comparison with the variety Senga Sengana. After temperature lowering, however, these values were more reduced than for plants of Senga Sengana, which can be interpreted as higher susceptibility of this variety to chill. Addition of BAP caused disturbance of primary photosynthesis reactions rate, particularly in lower temperature. Auxin 2,4-D had no effect on the luminescence parameters in comparison with control cultures. Dehydration stress strongly diminished the values of measured parameters for Ananasowa variety what indicates the inhibition of primary photosynthesis reaction in leaves. The old culture of Senga Sengana variety showed higher tolerance on linuron in comparison with the new one.
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