Kinetic analysis of potassium absorption in rice accessions with different allelopathic potentials

The ion-depletion method was used to explore the differences in two rice accessions (allelopathic rice “PI312777” and non-allelopathic rice “Lemont”) on potassium ion absorption. Simultaneously, different expressions of the genes involved in potassium ion absorption were determined by FQ-PCR. The results showed that variations in △K_m, -△I_max and △C_min in allelopathic rice “PI312777” were significantly lower than those in the non-allelopathic rice “Lemont”. The order of K_m and C_min values for two accessions under different treatments was as follow: no starvation treatment with Hoagland solution (K_Control) > starvation treatment with Hoagland solution (K_All) > starvation treatment with nutrient solution containing N, P and K (K_NPK) > starvation treatment with nutrient solution only containing N and K (K_NK) > starvation treatment with nutrient solution only containing P and K (K_PK) > starvation treatment with Hoagland solution without N, P and K (K_Other) > starvation treatment with nutrient solution only containing K (K_K). The reverse order was observed for I_max. The results showed significant effects of nutrient elements on potassium ion absorption in the two rice accessions. Nitrogen presented the highest effect, which followed by phosphorus. Different gene expressions indicated that the genes related with root potassium ion absorption in the two rice accessions were up-regulated. However, the expressions of the genes in non-allelopathic “Lemont” were higher than those in allelopathic rice “PI312777”. This suggested that non-allelopathic rice “Lemont” was more sensitive to environment disturbance than allelopathic rice “PI312777”.