In order to clarify the effects of chelate tetrasodium glutamate diacetate (GLDA) on the remediation of cadmium (Cd) contaminated farmland by Pennisetum purpureum Schum, GLDA was applied in different methods within 60 days:total application doses of 585, 1170, and 2340 kg·hm-2 were equally divided into 1-4 applications, respectively, and the time intervals of 2-4 applications were 30, 20, and 15 days, respectively. The biomass, Cd content, and amount of Cd extracted from aboveground parts of Pennisetum purpureum Schum, in addition to the pH, dissolved organic carbon (DOC) mass concentration, and other indicators in soil were analyzed. The results showed that the biomass and Cd content of the aboveground parts of Pennisetum purpureum Schum increased significantly when GLDA was applied many times at a low application dose. The number of applications and the total dose were the key factors influencing the biomass and Cd content, respectively. The highest amount of Cd extracted was 16.78 g·hm-2 at 585 kg·hm-2 (applied four times), which was 275.39% higher than the CK treatment (i.e., no GLDA was applied). There was significant positive correlations between the pH, mass concentration of DOC, and content of DTPA-Cd, and the total dose and number of applications. The mass concentration of DOC was the main factor affecting the DTPA-Cd content. The total Cd content in the soil (after at 585 kg·hm-2 was applied four times) decreased by 3.23% compared with that of the soil before planting Pennisetum purpureum Schum. Therefore, the application of GLDA is of great significance for the remediation of Cd contaminated farmland by Pennisetum purpureum Schum, and the application method should be selected reasonably.
Keywords: Pennisetum purpureum Schum; cadmium; farmland; remediation; tetrasodium glutamate diacetate(GLDA).