Gene flow in parapatric plant populations of Agrostis tenuis L.and Festuca rubra L.

The gene flow between populations of Agrostis tennis L. and Festuca rubra L. on a Zn/Pb mine and adjacent areas, which met at a distance of 150 m from the mine boundaries, was studied. It was found that the mine populations exhibit a high index of tolerance to Zn and Pb, elements encountered in the soil. Those outside the mine show relatively high indices of tolerance towards Zn and Pb, despite the fact that these elements are absent from the soil. On the other hand, the index of tolerance towards Cu, absent from the soil, of populations inside and outside the mine, was very low and did not differ from that of the control. Time difference in the flowering of these parapatric populations acts against gene flow thus resulting in a tendency for the neighbouring populations to isolate

Photoacoustic measurements of photosynthetic activities in intact leaves under copper stress

Photoacoustic spectroscopy was used to monitor Cu damage to photosynthesis by measuring photochemical energy storage (PES) at high frequency of 600 Hz and yield of O2 evolution (Aox/Apt) at low frequency of 19 Hz in intact leaves of a Cu-tolerant (Silene compacta) and a non-Cu-tolerant (Alyssum montanum) species. The results indicated that Cu affected root growth (RRG), more severely than photoacoustic parameters in both species. Plants of S. compacta grown in lower Cu concentration revealed an enhancement phenomenon on RRG, PES and Aox/Apt, in contrast, plants of A. montanum revealed a slight decrease in the above mentioned parameters. A remarkable decline of PES and Aox/Apt for both species, was observed, at higher Cu concentrations, a fact considered to reflect inhibition of the photsynthetic e- flow in thylakoids. PES was less affected by Cu stress than O2 evolution showing a differential sensitivity of two photosystems in Cu. Photosystem II (PSII) seemed to be more sensitive because of degradation and leakage of chloroplasts membranes, inducing a decline in yield of O2 evolution. On the other hand, PES was appreciable because of cyclic e- transfer around the intact or less inhibited photosystem I (PSI). © 1993.SCOPUS: ar.jinfo:eu-repo/semantics/publishe