|Merotto, jr., Aldo|
Submitted to: Advances in Agronomy
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/4/2014
Publication Date: 1/20/2015
Citation: Ziska, L.H., Gealy, D.R., Caicedo, A.L., Gressel, J., Vidotto, F., Lawton-Raugh, A.L., Theisen, G., Norsworthy, J., Ferrero, A., Vidotto, F., Johnson, D., Ferreira, F.G., Marchesan, E., Menezes, V., Cohn, M.A., Burgos, N., Linscombe, S., Carmona, L., Tang, R., Merotto, Jr., A. 2015. Weedy (red) rice: An emerging constraint to global rice production. Advances in Agronomy. 129:181-228. Interpretive Summary: Rice remains the most important food staple for a global population of seven billion. For thousands of years, rice has been transplanted and grown under flooded conditions to control weeds. Rice is a poor competitor with weeds, particularly with weedy (red) rice, and flooding and transplanting cultivated rice are necessary to achieve maximum yields. However, water availability is diminishing globally, as is labor availability, and many farmers are switching to planting rice seed directly into the soil. This is known as direct-seeded rice, or DSR. In this review, we utilize the knowledge of international experts to assess what this cultural transition means in regard to how weedy rice can reduce global rice production. We do this by examining the biological basis for weedy rice competitive advantages, including its evolution and genetics; quantifying how quickly weedy rice is spreading globally with adoption of DSR; and providing a number of regional and global management strategies to improve its detection and control. Lastly, we suggest a number of critical research areas that deserve additional attention if rice production is to be sustainable with diminished water and labor resources.
Technical Abstract: Ongoing increases in the human population necessitate that rice will continue to be an essential aspect of food security for the 21st century. While production must increase in the coming decades to meet demand, such increases will be accompanied by diminished natural resources and rising production costs that will alter how rice is grown and managed. Such resource constraints are the impetus for the current transition from traditional flooding and transplanting to direct-seeded rice (DSR). However, such a transition can result in an increase in pest pressures, especially weeds. Rice production can be particularly vulnerable to weed competition, with significant yield losses (i.e., >50%) occurring. Among pernicious weeds, weedy (red) rice (Oryza sativa L.) is increasingly recognized as a major constraint in achieving maximum yields in DSR. This is due, in part, to its phenotypic similarity to cultivated rice lines and its ability to negatively influence qualitative and quantitative aspects of production. As rice will continue to serve as a cornerstone for future food security, a comprehensive assessment of weedy rice impacts associated with increasing adoption of DSR is both timely and critical. In this review, we examine the biological basis for the competitive ability of weedy rice, including its evolution, ecophysiology and genetics; quantify spatial-temporal shifts in its distribution and spread; and emphasize and outline a number of regional and global management strategies for its detection and control. Lastly, we suggest a number of critical research areas that deserve additional scrutiny with respect to weedy rice management.