Abstract:

【Objective】 The objective of the experiment is to study the mechanism of potassium application on improvement of maize resistance to stalk rot at cell level. 【Method】 Scanning electron microscope and transmission electron microscope were used to observe the effect of K on the ultrastructure of maize stalk pith tissue and young root tip cell influenced by K and pathogen. 【Result】 In K deficient treatment, parenchyma cells of stalk pith had abnormity structure and the cell wall between upper and lower adjacent cell was broken, resulting in the loss of connections between vascular cells and bad supporting capacity. In addition, improved K nutrition also helped in keeping a quite tight arrangement of root cell with thick cell wall, prevented the invading of pathogen effectively. Moreover, K treated root cell had abundant golgi apparatus, which could excrete large amount of secretions to degrade mycelium. Papillary and highly electronic intensity dot were accumulated in the invading point to prevent the development of the mycelium. 【Conclusion】 Improved K nutrition could increase the resistant ability of maize plant to stalk rot, through keeping cell structure stability and preventing the expansion of intracellular space to reduce the chances of pathogen invasions; through reinforcing cell wall and formation intercellular and intracellular material to restrict pathogen further development in host cell.

Key words: potassium (K), maize stalk rot, ultrastructure, disease resistance