Abstract:
Weedy rice (Oryza sativa f. spontanea) is a conspecific weed that has invaded cultivated rice fields, effectively
adapted to modern management practices, leading to substantial yield losses and reduced harvest quality. The
understanding of weedy rice genetic diversity and population structure is critical in developing effective control
measures. Twenty weedy rice populations were collected around the island and evaluated using 33 SSR markers.
Our findings indicated that the genetic diversity (He) in a population of weedy rice was reasonably high (0.305 -
0.560). A high level of within-population (79%) and a low level of among-population (21%) genetic variation were
found by analysis of molecular variance (AMOVA). There is no significant correlation across genetic and
geographical distances (P>0.05). The unweighted pair group method with arithmetic mean (UPGMA)
demonstrated that 20 populations were structured into two well-separated groups. Remarkably, many admixed
individuals were evident according to the STRUCTURE. Weedy rice management strategies should focus on
micromorphological monitoring to detect, group, and eliminate weedy rice in paddy fields, restricting the
exchange of saved paddy seeds among geographical regions, increasing the production and distribution of
certified seeds, the varietal recommendation for rice-growing regions to minimize mixing of varieties with
different age classes, raising awareness are the recommendations to reduce the emergence of future weeds
