Effects of diethyl aminoethyl hexanoate on seed germination characteristics of white clover under chromium stress

White clover (Trifolium repens ‘Haifa’) was selected as experimental material, and the effects of soaking seeds in diethyl aminoethyl hexanoate (DA-6) on tolerance of chromium (Cr) stress during germination were studied. The results showed that a 5 mmol·L⁻¹ Cr⁶⁺ solution significantly inhibited seed germination (P < 0.05). DA-6 at 40～60 mmol·L⁻¹ significantly increased the germination index of white clover under chromium stress (P < 0.05), and the greatest effect was achieved at a concentration of 60 mmol·L⁻¹. Moreover, free proline and soluble sugar increased by 1.6 and 3.8 times, respectively, and cell osmotic potential was significantly decreased by 178% for seeds soaked in DA-6 during germination under Cr⁶⁺ stress (P < 0.05). The antioxidant enzyme activity and key enzymes involved in the ascorbate-glutathione metabolism cycle of seeds soaked in DA-6 significantly increased (P < 0.05), thereby reducing oxidative damage and improving cell membrane stability during germination under Cr⁶⁺ stress. These results indicate that DA-6 significantly improves the seed germination rate and Cr⁶⁺ tolerance of white clover during germination and early development, which are closely associated with enhancement of osmotic adjustment and improvement of antioxidant defense.