Salinization of crop fields under desertification closely relates to root absorptive functions of the major crops such as corn and sunflower plants. The rate of root salt absorption of corn and sunflower plants under the salinized condition were analyzed by applying the transpiration-integrated model of root ion absorption affected by leaf transpiration. The characteristics of root salt absorption were represented by two model parameters of gmi and Kj which relate to the potential absorbing power and the ion affinity of transport proteins on root cell membranes, respectively. In particular, the model parameter of Qmi can be an explanatory parameter to represent the specificity of plant species and ion species in root ion absorption. Identification of gmi involved in the transpiration-integrated model of root ion absorption can be effective for simulating salt accumulation in crop fields under desertification.