Neglected wild rice (Oryza spp.) in Sri Lanka

Abstract

In Sri Lanka, five wild rice species are reported; Oryza nivara [AA], O. rufipogan (AA) O. eichengeri [CC], O. rhizomatis (CC) and O. granulate (GG). Wild rice is the presumed progenitor/s of cultivated rice and is distributed in tropical wetland ecosystems of the world.  Wild rice specie often thrives and evolve in wetlands are now neglected. Out of the total of five wild rice species, three are commonly grown in wetlands.  The present review describes five wild rice species individually and their treats have also been documented. Wild rice species in the wetlands of Sri Lanka indicates a decreasing trend. Several factors contribute to the decrease in wild rice communities. Degradation of habitat due to the environmental pollution, national developmental projects, agricultural activities and climatic change associated drought and floods stands as dominant factors.  Building awareness among the communities living associated with the wetlands is one of the important activities to reduce further deterioration of the reduction of the wild rice species in Sri Lanka. Restoration of wild rice communities introducing community participatory programmes with relevant authorities are recommended.

Although five wild rice species are reported, the precise number of wild rice species in Sri Lanka becomes uncertain and thus, need to assess Oryza species complexes in Sri Lanka using morphological, anatomical, and molecular characterization information to enumerate number of species within each Oryza complex and of species and species complexes. Characterization of wild rice species was attempted through agro-morphological, anatomical and molecular characterizations. O. rhizomatis and O. eichingeri (CC) are well separated from the rest of the wild rice species (AA). Molecular data revealed, O. nivara and O. rufipogon have undergone independent evolution within Sri Lanka. Well separated five wild rice species are present in Sri Lanka. The findings led to conclude that wild rice species in Sri Lanka are “ecological swarms” and represents allopatric or sympatric populations. A comprehensive knowledge on genetic diversity and population structure of wild rice germplasm in Sri Lanka is useful to incorporate them in rice breeding programs.