Distribution patterns and genetic relationships of weedy rice (Oryza sativa f. Spontanea) populations in different climatic zones in Sri Lanka

Weedy rice (Oryza sativa f. spontanea) (WR) is widely distributed in rice growing areas in all climatic zones in Sri Lanka and shows spatial distribution and genetic affinities to cultivated rice. The present study attempts to relate the agro-morphological and molecular data to the distribution pattern/s of WR populations in different climatic zones. WR eco-types were collected from five different locations in twelve districts representing Wet, Dry and Intermediate zones. Five replicates of each eco-type planted in plastic pots and arranged in CRD. Agro-morphological characterization of WR, wild rice and cultivated rice was based on the Standard Characterization Catalogue. Ten SSR primer pairs were used for molecular study. Capillary electrophoresis was performed using GENE MAPPER software and identified different peaks among samples. The principle component analyses (PCA) were carried out for data. PCA of morphological variables of WR populations results nine components explaining 73.87% and 10 labeled SSR primer pairs resulted six components explaining 80.34% of total variation. Occurrence of agro-morphological characters of WR, wild and cultivated rice showed a weak trend with climatic zones. The pattern of genetic diversity and differentiation of WR populations suggest the common origin centered on the species; O. nivara for dry zone WR eco-types and O. rufipogon for wet zone eco-types.