Effects of pH and N forms on the distribution of Ca2+ in wheat root

Transmission electron microscopy was used to observe effects of two pH levels(4.0 and 6.0)and nitrogen forms(NH4+-N,NO3--N) on the root ultrastructure and Ca2+ distribution in wheat root.Results obtained were the following: 1) Ca2+ content in wheat root cells at the pH 4.0 was lower than that at pH 6.0;2) Low pH could induce plasmolysis of wheat root cells;3) Ca2+ in wheat root cells,especially in intercellular substances,cell wall and cell membrane,with NH4+-N as nitrogen source was significant lower than NO3--N;and 4)Ammonium nitrogen was also able to induce plasmolysis,structure loss and cytoplasm outflow of wheat root cells.Low pH could exacerbate these symptoms.