THE ATPASE ACTIVITY IN PHLOEM OF SUGARCANE STEM AND ITS FUNCTION IN SUGAR TRANSPORT

The effects of four mediums with different ions and pH value, incubating the transport tissue sections, on ATPase activity of phloem cells of different internodes in two sugarcane varieties was studied in this paper by cytochemical technique. The changes of ATPase activity of phloem cells of sugarcane in different age was also investigated. The results showed that ATPase activity of sugarcane stem phloem has significant difference in the present of different ions and pH value.Mg++ and cl- gave the greatest stimulation to phloem ATPase and the ATPase activity showed higher in the medium with pH 6.5 than with pH 7.2. The phloem ATPase activity of the same position internode in different age showed different, and which consisted with the increase of sugar accumulation with cane ripening. It was suggested that sugar unloaded from phloem in suggarcane stem was active process and speculated that, with the enzyme cytochemical technique, the characteristics of membrane located ATPase activity of phloem cellse which are difficult to isolate and their effection on phloem transport may be known qualitatively and directly.