[Safety evaluation of allelochemical derivative pyrone on different millet varieties]

The development of new herbicides based on allelochemicals is a potential strategy of weed control in arable field. Pyrone, a novel derivative of tricin, has significant inhibitory effects on weeds. Its safety for crops, especially for millet that are sensitive to commercial herbicides, is still poorly understood. In this study, germination test and pot experiments were conducted to evaluate the safety of pyrone on 20 millet varieties, compared with 2,4-D. The results showed that, except that Jinfen109 was sensitive to high concentration 2,4-D, both pyrone and 2,4-D had no effect on the germination rates of other varieties. Results of the pot experiment showed that pyrone treatment significantly increased the chlorophyll content of millet by 9.0%-67.9%, which was the greatest for Jigu 42. Pyrone treatment did not affect maximal photochemical efficiency, potential photochemical activity, actual photochemical efficiency, and non-photochemical quenching coefficient. On the contrary, 2,4-D significantly inhibited the fluorescence parameters of millet varieties. Pyrone treatment increased the activities of superoxide dismutase, peroxidase and catalase in leaves of Dunza16, Jigu 39, Jigu 41 and Jingu 28, with the magnitude of enhancement being higher than 2,4-D. The results indicated that the allelochemical derivative pyrone is highly safe to the growth of millet seedlings and has the potential to be a new herbicide to millet field.