# Growth Variation Among Thai Duckweed Species Under Axenic Conditions

## TL;DR

This study compares the growth rates of different Thai duckweed species under controlled, sterile conditions to identify the most productive strains for applications like animal feed and wastewater treatment.

## Contribution

The study provides the first systematic comparison of duckweed growth rates in Thailand under axenic conditions and establishes a standardized growth measurement protocol.

## Key findings

- Significant intraspecific variation in growth rates was observed among duckweed species.
- Wolffia globosa showed the highest relative growth rate of 0.162 day−1 and exponential growth after 35 days.
- A standardized protocol for measuring duckweed growth under axenic conditions was established.

## Abstract

Duckweed is a small aquatic plant that can grow rapidly and produce high amounts of protein, making it applicable for various applications, including animal feed, wastewater treatment, and human food. To reach its full potential, we need to understand how different species of duckweed grow and whether their growth differs within the species. So far, studies have determined the growth in natural settings, making it difficult to separate the effects of the environment from genetics. In this study, we grew four duckweed species in the same sterile conditions. We obtained various strains from multiple locations in Thailand and measured how fast they grow. We found that strains within the same species grew at different rates, and different species had different growth patterns. The results provide the first systematic comparisons of baseline growth rate data for duckweed species in Thailand, as well as a standardized method for measuring growth under controlled conditions. This knowledge will allow researchers and industries to select the most productive strains for their respective applications.

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, Landoltia punctata (G. Mey.) Les & D. J. Crawford, Lemna aequinoctialis Welw., Spirodela polyrhiza (L.) Schleid., and Wolffia globosa (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 S. polyrhiza to 0.162 day−1 in W. globosa. Significant intraspecific variation was observed in L. punctata, S. polyrhiza, and W. globosa, 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 W. globosa 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.