Toxic Effects of Phthalate Plasticizers in Soil on Different Cucumber Varieties

Plasticizer di(2-ethylhexyl)phthalate (DEHP) is a typical environmental endocrine disruptor with environmental persistence. The residue of DEHP in the soil can be absorbed into plant by roots, affecting plant growth and physiological and biochemical functions. The soil contamination method was used for seed germination experiments, and the results show that different cucumber varieties had significant differences in response to DEHP pollution stress. DEHP could inhibit the germination of the most cucumber varieties. Under the treatment of DEHP, the germination rates of the seed Jinyou 1, Tangshan autumn cucumber, Taiwanhugua, Jinsheng 103, Bomei 8, Derit 79, Deer LD-1, Fengyuan 1, Lüying 06-8, Lüfeng 18-15, Hanxiu 07-3, Hanxiu 3-6 and Xinyue 917 varieties were 86.67%-96.67%, indicating good resistance to DEHP. Except for the three varieties of Zhongnong C18, Bomei 8, and Ma cucumber, the inhibition rate of DEHP on seedling shoot length of other cucumber varieties was 7.72%-52.46%. The response of root vitality of different cucumber varieties to DEHP stress varied greatly. The activation rates of DEHP on the root vitality of Tangshan autumn cucumber, Shenqing 1, Zhongnong C18, Jinsheng 103, Bomei 8, Derit 79, and Zhizun 187 varieties were 27.45%-772.03%; The inhibition rates of DEHP on proline content in most cucumber seedlings were 16.41%-53.86%, and the activation rate of proline in Jinsheng 103 variety was 70.67%; DEHP could promote soluble sugar content of seedlings of the 14 tolerant cucumber varieties, resulting in significantly higher soluble sugar content than the control (P<0.05), with activation rates ranging from 71.52% to 859.35%; DEHP could inhibit protein synthesis in most cucumber seedlings, with inhibition rates ranging from 17.86% to 65.76%. The results of comprehensive evaluation of the toxicity of DEHP on 14 cucumber varieties using radar area show that the 7 cucumber varieties, including Zhongnong C18, Shenqing 1, Zhizun 187, Taiwanhugua, Jinsheng 103, Bomei 8, and Derit 79, had strong tolerance to DEHP. This study lays the foundation for further screening cucumber varieties with high tolerance to and low bioaccumulation of DEHP, and it provides theoretical basis for vegetable cultivation in polluted soil.