Rapid Translocation in the Phloem of Wheat Roots

Abstract

When wheat seedlings are forced to grow with only one seminal root, very high rates of mass transfer occur in the phloem of the root base. This transfer is many times faster than any reported in phloem from other tissue, and is too fast to be explained by either motile or electro-osmotic mechanisms. However, it does not conflict with the Münch hypothesis providing the usual assumption is made that the sieve pores are not blocked. Despite the unusually rapid transfer, the growth of the roots appears to be in no way limited by the ability of the phloem to transport assimilates to the growing points.