Effects of long-term herbicide application on the crops in soybean-peanut rotations in the red soil upland of Southern China

Abstract Aiming at the problem that the amount of chemical herbicides input is continuously increasing, it may be result in the severe organic chemical pollution, and the negative influence on crop growth is also enhancing in the red soil upland of southern China. Therefore, a long-term location experiment was founded to research the effects of herbicide acetochlor on the crops growth, physiology and yield in soybean-peanut rotations in the red soil upland. The data in 2013 and 2014 indicated that the rate of emergence, number of leaves, stem diameter, plant height of peanut and soybean seedlings were declined by herbicide acetochlor with long-term application, the seedling growth was limited obviously. The root nodule number, shoot dry matter and SPAD value of peanut and soybean were significantly decreased by herbicide acetochlor at four critical growing stages. Moreover, the leaf malondialdehyde (MDA) content, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities of peanut were significantly decreased by acetochlor at four critical growth stages. As for soybean, the leaf MDA content at four critical growth stages and SOD and POD activities at seedling stage were significantly enhanced by acetochlor with long-term application, but SOD and POD and CAT activities at pods bearing stage and mature stage were significantly dropped. The yield components of peanut such as plant height, lateral branches number, 100 pods weight, shelling rate and yield were reduced under the treatment of herbicide acetochlor. The plant height, branches number, 100 grains weight, and grain yield of soybean were significantly decreased by the acetochlor treatment, but the empty pods rate was significantly increased. The annual yield in 12 years indicated that long-term acetochlor application reduced the yield of peanut and soybean, and the range of yield reduction was gradually aggravated with the increasing years of application. Compared with manual weeding, the yield decreasing range of soybean was from 5.64%–13.14% and the yield decreasing range of peanut was from 3.85%–12.49% under acetochlor treatment from 2006 to 2017.