Growth Variation Among Thai Duckweed Species Under Axenic Conditions

Duckweed has attracted considerable attention for its high protein content, rapid growth, and broad potential in biotechnological applications. Understanding key phenotypic traits is crucial for unlocking and maximizing this potential. While most studies on duckweed growth have been conducted under natural or non-sterile conditions, here we minimize environmental influences and focus on the genetic component of growth by assessing growth performance under axenic culture. In this study, we measured relative growth rate (RGR) in four duckweed species, <i>Landoltia punctata</i> (G. Mey.) Les & D. J. Crawford, <i>Lemna aequinoctialis</i> Welw., <i>Spirodela polyrhiza</i> (L.) Schleid., and <i>Wolffia globosa</i> (Roxb.) Hartog & Plas. collected from various natural locations across Thailand. A total of six to seven strains were tested for each species. The relative growth rates of studied species ranged from 0.012 day^-1 in <i>S. polyrhiza</i> to 0.162 day^-1 in <i>W. globosa</i>. Significant intraspecific variation was observed in <i>L. punctata</i>, <i>S. polyrhiza</i>, and <i>W. globosa</i>, with the coefficients of variation between 9.6 to 109.9 percent. Each strain showed distinct growth characteristics: Most displayed a steady growth pattern, whereas <i>W. globosa</i> showed exponential growth at Day 35 after the start of experiment. The results provide the first systematic comparisons of baseline growth rate data for duckweed species in Thailand. These findings advance the understanding of strain-specific growth traits in duckweed and establish a standardized protocol for evaluating growth traits under axenic conditions, providing a basis for future research and applications.