[Allelopathic influence of Myriophyllum spicatum on the photosynthetic efficiency of Microcystis aeruginosa].

The allelopathic influence of Myriophyllum spicatum on chlorophyll content and chlorophyll fluorescence parameters of Microcystis aeruginosa was studied in coexistence condition. Chlorophyll fluorescence parameters included q(N) (non-photochemical quenching), Y II (effective quantum yield), F(v)/F(m) (maximum quantum yield), F'(v)/F'(m) (effective quantum yield of photosystem II photochemistry) and ETR (electron transport rate). During the three days under coexistence condition, chlorophyll content and chlorophyll fluorescence parameters of M. aeruginosa were affected by M. spicatum and presented different sensitivities. Chlorophyll content of M. aeruginosa was significantly inhibited by 20.80% on the second day at 10.0 g/L of M. spicatum (P < 0.05). However, chlorophyll fluorescence parameters of M. aeruginosa decreased earlier and rapider than chlorophyll content. On the first day, q(N) and Y II of M. aeruginosa were significantly inhibited by 15.59% and 13.00% at 5.0 g/L of M. spicatum (P < 0.05), and F(v)/F(m) and F'(v) /F'(m) were declined by 15.87% and 12.07% at 10.0 g/L (P < 0.05), respectively. On the third day, ETR and three parameters based on ETR were affected at all levels of M. spicatum (P < 0.05). The inhibition effects on the photosynthetic activity of M. aeruginosa might be considered as one of the target sites of M. spicatum and chlorophyll fluorescence parameters were more sensitive parameters than chlorophyll content, especially q(n).

[Application of selective microelectrode in plant physiological research].

Selective microelectrode technique, known as an electrophysiological approach, can be used to measure directly specific information on ion or molecule distribution and movement both inside and outside of living organelle, biological cells, tissue and organs. It has several advantages over other methods in measuring ionic or molecular information, e.g. easy to handle, fast response, high sensitivity (10(-12) moles cm(-2) s(-1)) and non-invasive to the samples in addition to continuous measurement and automatic monitoring. Microscopic-scale selective electrode (with a tip diameter of 0.5-5 microm) can be used to measure net fluxes of ions or molecules outside of growing biological cells, tissues and organs, to measure activities of ions or molecules inside of growing organelle and biological cells. Thus, it has many applications in various research fields. The technical principle of design and use of selective microelectrode and its progress and development prospect in plant physiological research are summarized.