Benefits of mechanical weeding for weed control, rice growth characteristics and yield in paddy fields

Context: Mechanical weed control method with autonomous weeding machine provides an alternative way for farmers to reduce the use of herbicides. This method can not only reduce the chemical load in the environment, but also have many other benefits, such as loosening soil and promoting plant growth. However, little is known in this regard. Therefore, field experiments were conducted to determine the benefits of mechanical weeding on rice growth.Objective: The main objective of this study was to investigate the effects of mechanical weeding on weed control, rice growth characteristics and yield. The ultimate goal was to provide an efficient, non-chemical weed control method for rice production.Methods: Three field experiments were conducted in 2020 and 2021 using an autonomous weeding machine that combined inter-row and intra-row weeding technologies. Three different rice cultivars (Qingyang, Yue-taiyouzhan, and Huahang 57) were grown in the three experimental sites in South China. At each site, the experimental treatments were mechanical weed control and chemical weed control. Plants with no weed control were taken as the control of the experiment. Weed control efficacy and crop performance were measured.Results: The results showed that mechanical weeding using the autonomous weeding machine was able to achieve a high level of weed control efficacy (on average 80 %) for three weeks after weeding, and also reduced farmers' time and labor for weed management. Mechanical weeding significantly increased the tiller numbers by 7-23 %, SPAD values by 3-7 %, as well as the total biomass by 45 % after the jointing growth stage, compared with the chemical weed control method. Furthermore, the mechanical weeding obviously increased the activities of su-peroxide dismutase and peroxidase in the uppermost leaves of rice plants and grain yield by 2-11 % at the harvest maturity stage.Conclusion: Mechanical weeding using the collectively inter-row and intra-row weeding technology was capable of avoiding using herbicides with no losses in weed control efficacy and grain yield. Due to the mechanical stimulation and inter-tillage effect of the autonomous driving weeding machine, the mechanical weed control method promoted rice growth, which provided an efficient and non-chemical weeding method for rice production.Significance: The continuing advancement of this emerging technology is of great significance to the development of weed control in field crops. The results could be used to enhance rice production using mechanical weed control methods and develop smart-agriculture practices in China and similar agroecological regions around the globe.