The Munch’s hypothesis or mass flow or pressure flow hypothesis is proposed by E. Munch in 1930. By this theory Munch explained how the translocation of the solutes occurs in plants. Photosynthesis results in the production of the higher concentration of the organic food materials in the mesophyll. Since the solute concentration is higher the osmotic pressure is also high in the mesophyll cells. When the water then enters the mesophyll cells the turgor pressure increases. This increase in the turgor pressure which results in the mass flow of organic solute through the phloem down from the stem to the root. In the cells the photosynthate are consumed or converted into the insoluble form for the storage and the excess amount of the water is converted into the soluble form.
