Weedy rice: A threat to rice production in Sri Lanka

Weedy rice (Oryza sativa L. f. spontanea), one of the four most significant weeds, is globally well known as a problem in the rice industry. The economic and environmental problems they pose include those related to rice crop production, milling for commerce, quarantine regulations and seed trade. Weedy rice possesses a number of common features with other weeds and distinctive characteristics such as phylogenetic and morphological resemblance to cultivated rice. Weedy rice is a difficult-to-manage weed when coexists in rice ecosystems causing economic losses to rice. Currently, weedy rice has been found in nearly all the rice growing regions in Sri Lanka. The estimated rice yield losses caused by the infestation of weedy rice varied largely from 40% to 90%, depending on its density and degree of shattering in rice fields. Effective control of weedy rice must be taken into immediate consideration to secure rice production in the country. The promotion of the use of certified seed paddy without weedy rice contamination should be the immediate and key step in the implementation of efficient control mechanism followed by other integrated weed control measures to reduce the proliferation and limiting its distribution to non-contaminated areas. However, the outcome will be limited except all parties in the rice industry are unified and committed to control weedy rice. In contrary to all unfavorable impacts of weedy rice on rice production, high heritability values coupled with high genetic variability of its favorable characteristics could be considered in rice improvement programs and in broadening the rice gene pool. Journal of the University of Ruhuna 2015 3(1): 2-13