CHANGES OF ELECTRIC-POTENTIAL IN WHEAT PISTILS INDUCED BY POLLINATION

We investigated changes of electric potential induced in wheat (Tritic um aestivum L.) pistils by pollination with wheat or maize (Zea mays L .) pollen. Electric measurements were made in a monophasic system with Ag/AgCl/0,1 M KCI microelectrodes ended with glass capillaries (o 1.5 -3 mu m). The reference electrode was implanted into the embryo sac wh ile the measurement electrode was in a surface contact with one stigma tic stylodium. We pollinated 15 min after the implantation of electrod es. Control experiment showed that maize pollen tubes grew much slower than wheat ones. The potential was recorded for 20 min after pollinat ion in 10 selfpollinated wheat pistils and for 70 min in 16 wheat pist ils pollinated with maize. After measurements pollen tube growth was e xamined with aniline blue under fluorescent microscope. In selfpollina ted pistils of wheat the potential decreased quickly and stabilized at -10 mV +/-3 mV to the initial level. The fastest rate of changes acco mpanied the penetration of the stigmatic hair and the growth of pollen tubes in stylodia. In wheat x maize crosses the potential decreased i n every pistil before emergence of pollen tubes. When germination was successful, the potential remained negative. Its minimal value ranged from -3 to -84 mV and was correlated with the number of pollen tubes f ound in the stylodia. When grains fail to germinate the potential incr eased. All the recorded changes of potential were long lasting waves w ith slowly growing amplitudes.