Sustainability, Efficiency, and Circularity of Weedy Rice Management Strategies

Weeds have always been a serious problem for farmers and especially nowadays given the current challenges related to food security and agriculture sustainability. During the last three decades, the increasing scarcity of labor, energy, and water has led to a switch of the rice establishment method from traditional hand transplanting to direct seeding. While the latter presents some advantages, it also fosters weeds among which weedy rice is considered the worst because it has a strong competitive ability, and as a congeneric of cultivated rice is very difficult to control. There are currently three main weed management strategies in rice: synthetic herbicides, herbicide-resistant rice varieties, and integrated weed management (IWM). However, all these strategies have low effectiveness and sustainability. Even though IWM is strongly recommended, its adoption remains very low owing to its complexity and the additional cost it induces. The use of crop rotation and cover crops is sustainable and consistent with the circularity principles, but this strategy presents the same drawbacks than those associated with IWM. We stress that other strategies used to control or suppress weedy rice are more efficient, sustainable, and consistent with the bioeconomy principles. They encompass the control of the pathways to weediness by ferality as well as the improvement of rice cultivars' fitness based on allelopathic effects. Other non-chemical weed management strategies, such as the use of bioherbicides, are promising given the current transition towards bioeconomy and circular economy.