Study on root growth and root hair morphology in different flue-cured tobacco varieties under low potassium stress

Agar plating culture technology was used to study difference of root growth and root hair morphology in flue-cured tobacco varieties of K326,NC82,Yunyan87,RG11 and Honghuadajinyuan at seedling stage under low-potassium stress. Results showed that growth of up-ground part and under-ground part of seedling from different varieties was significantly influenced by low-potassium stress. The inhibition extent of low-potassium stress on dry weight of above ground part and root at seedling stage was in the sequence of RG11 Honghuadajinyuan and Yun85 NC82 and K326. There existed significant differences on response ability of roots to low-potassium stress among different varieties,and inhibition extent of root morphology roughly represented in the order of Yun85 and RG11K326 and Honghuadajinyuan NC89. The increase range of root hair density was NC82 K326Yunyan85 Honghuadajinyuan RG11,and the descent range of root-shoot ratio was RG11 and Yun85 NC82 and K326 Honghuadajinyuan,whereas the root-shoot ratio of NC82 was optimal. The results also indicated that root distribution of different varieties was discriminatory,and the roots of RG11 and Honghuadajinyuan were mainly distributed below 2cm,K326 was below 3 cm,Yunyan85 and NC82 was of between 3 and 5 cm. Therefore,low-potassium tolerance of NC82 was better than that of other 4 varieties,and total length of roots per plant and root hair is important indexes of potassium stress,nutrient use efficiency and stress resistance in flue-cured tobacco varieties,and plating culture technique could be made to research the potassium nutrition characters of flue-cured tobacco germplasm resources rapidly and efficiently.