PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Azolla is a floating aquatic plant that offers numerous advantages, including high growth rates and significant protein content, making it a valuable resource for animal feed, fertiliser, and a potential carbon capture agent. Taxonomic analysis and the diversity of Azolla in Indonesia remain unclear. Therefore, this study explores the diversity of Azolla species in the Progo and Opak river basins, using 20 morphological characters and 10 primers of inter-simple sequence repeat (ISSR). Morphological characters that strongly contribute to differences between genotypes are branching patterns, dorsal lobe shapes, presence of ventral stomata, lobe length, hyaline ratio, and number of branches. The genotypes are identified as Azolla cristata, which are synonyms of conspecific species Azolla mexicana and Azolla microphylla. Among 10 inter-simple sequence repeats (ISSR), UBC 814 and UBC 841 exhibit the high PIC (0.29; 0.28) and RP (19.71; 23.29), respectively. The unweighted pair group method cluster analysis grouped the accessions into two clusters based on their morphological and genetic traits. Diversity indices were moderately high across the two populations, with Nei’s gene diversity (He) = 0.230 and Shannon’s information index (I) = 0.342. AMOVA revealed that 93% of the overall genetic variation occurred within populations, while only 7% was attributed to differences among populations. The low differentiation suggests high gene flow between the two river basins, likely facilitated by water currents, waterfowl, or humans, effectively maintaining a single large, genetically diverse metapopulation.