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Being divided into three groups-strong, moderate and weak-according to the different kinetic parameters (Fmax, km, Cmin) of potassium uptake by crops, 21 cultivars of rice have been studied to find out the relationships between their potassium nutrition and the oxidation-reduction status in the rhizosphere soils.Results show that, with no application of K fertilizer, there were higher contents of active reducing substances and ferrous iron in rhizosphere soils planted with cultivars, such as Zhongguo 91, week in absorbing potassium than in soils cropped with cultivars, Shanyou 64, stronger in absorbing potassium. As a result of K application, however, these toxic substances were decreased appreciably in the soil, particularly in the root zone where weakly K-absorbing cultivars were growing, and the parameter of soil redox (pH +pE) was increased, the most striking example of this being found in the rhizosphere soil where the more strongly K-absorbing cultivars were growing. On and close to the root surfa
Being divided into three groups-strong, moderate and weak-according to the different kinetic parameters (Fmax, km, Cmin) of potassium uptake by crops, 21 cultivars of rice have been studied to find out the relationships between their potassium nutrition and the oxidation Results of the rhizosphere soils with cultivars, Shanyou 64, stronger in absorbing potassium. As a result of K application, however, these toxic substances were less appreciably in the soil, particularly in the root zone where weakly K -ving cultivars were growing, and the parameter of soil redox (pH + pE) was increased, the most striking example of this being found in the rhizosphere soil where the more strongly K -umped cultivars were growing. On and close to the root surfa