Effects of mutual intercropping on cadmium accumulation in seedlings of three varieties of eggplant

The aim of this study was to determine the effects of mutual intercropping on cadmium (Cd) accumulation in three different varieties of eggplant (Solanum melongena L.). Seedlings of three eggplant varieties (red, green and black) were intercropped with various combinations in Cd-contaminated soil and their Cd accumulation characteristics were compared. These three varieties of eggplant mutual intercropping treatments led to increased root, stem, leaf, and shoot biomasses of eggplant seedlings compared with their respective monocultures. The shoot biomasses of red, green, and black eggplant seedlings were 27.88%, 10.31%, and 6.06% higher in three-varieties intercropping treatment than in their respective monocultures. Mutual intercropping decreased the biomasses of different organs of green and black eggplant seedlings compared with their respective monocultures, and of red eggplant when intercropped with green eggplant, but increased those of red eggplant intercropped with black eggplant. The trends in photosynthetic pigment contents and antioxidant enzyme activity were similar to those of biomass. Mutual intercropping significantly decreased the Cd contents in roots of the three varieties of eggplant, but increased the Cd contents in their stems, leaves, and shoots. Intercropping of the three eggplant varieties increased the Cd contents in shoots of red, green, and black eggplants seedlings by 21.26%, 39.04%, and 4.87%, respectively, compared with their respective monocultures. Because mutual intercropping promotes the Cd absorption of eggplant seedlings in Cd-contaminated soil, it may not be a suitable cultivation strategy for eggplant in Cd-contaminated areas.