Weedy rice and the sustainability of alternative establishment methods

Abstract

Given its dependence and influence on the environment, and its importance for food security, several initiatives aim to improve the sustainability of rice cultivation. The most widespread recommendation is a switch from hand transplanting to direct-seeding. In the short-term direct-seeding presents social, economic and ecological advantages, however it induces in the longer term a major problem, the proliferation of weeds, in particular of weedy rice. The latter lowers grain yield and quality, and therefore farmers' income. Since weedy rice is a conspecific of cultivated rice, then it is very difficult to control it by either traditional means or biotechnologically because it promotes crop-weed hybridisation and the introgression of traits such as herbicide resistance. In addition to their low effectiveness, these weed management methods imply in the long-term important economic and ecological costs that reduce, or even might cancel, the short-term benefits associated with the switch to direct-seeding.