The effect of picloram herbicide on the physiological responses of Eupatorium adenophorum Spreng

Xiaowen Liu1-2, Chengmei Qi2, Zongcheng Wang2, Yuan Li1, Qiuxia Wang1, Meixia Guo1, and Aocheng Cao1*
Eupatorium adenophorum Spreng., a major invasive weed in southwestern China, has caused great economic losses. In order to find a new herbicide to control E. adenophorum, experiments were conducted to study its physiological and biochemical responses to low and high doses of picloram herbicide (4-amino-3,5,6-trichloropyridine-2-carboxylic acid). Electrolyte leakage, malondialdehyde, and free proline were stimulated by picloram, showing a remarkably increase (p < 0.05) with high herbicide concentration (60, 120, and 240 g ai ha-1). The treated plants exhibited lower osmotic adjustment capacity, high dosage lipid peroxide levels and more free-proline accumulation. It was found that low doses (12 and 24 g ai ha-1) of picloram initially increased catalase, peroxidase, superoxide dismutases and protein, but these indicators decreased (p < 0.05) with the increase of treating time (after 3 d) and dose (120 and 240 g ai ha-1). In addition, the structures of chloroplasts and mitochondria were seriously deformed. These results indicated E. adenophorum can improve its herbicide-tolerance by increasing the antioxidative system activity at the initial period of low picloram stress. However, this protective function disappeared with increasing of treating time and picloram dosage. Eupatorium adenophorum responded differentlyto low and high concentrations of picloram and ultrastructural changes are an important cause of death in E. adenophorum.
Keywords: Picloram,Eupatorium adenophorum, response of physiology and biochemistry
1Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China. *Corresponding author (caoac@vip.sina.com).
2Hunan University of Science and Engineering, Life Science & Chemical Engineering Department, Yongzhou, 425199, China.