PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Rice productivity on marginal land is significantly affected by salinity stress. However, biological approaches to improve rice growth tolerance remain insufficiently explored. This study aimed to evaluate the potential use of various actinomycete strains (SD 008, SD 021, SD 027), microalgae (Chlorella sp.), and their consortia to improve rice seedling growth and the physiological responses under different salinity levels (0, 50, and 100 mM NaCl). Rice seedling growth was assessed using several parameters, including seedling height, root length, number of roots, number of leaves, and biomass. In addition, the physiological condition of the plants was analysed using stress indicators consisting of chlorophyll a and b contents, proline, and malondialdehyde (MDA) accumulation. The results showed that treatment with strain SD 027 and the actinomycetes-microalgae consortium had a significant effect on several growth parameters. This treatment was able to increase the germination index, maintain root development, and enhance chlorophyll content under moderate to high salinity conditions. Furthermore, the increase in proline content, coupled with a decreased MDA level, indicates an improvement in plant tolerance to oxidative stress. Our findings indicate that the combination of actinomycetes and microalgae provides a synergistic effect in enhancing rice seedling growth under salinity conditions. This approach has the potential to be developed as a more environmentally friendly strategy to support plant growth on degraded land. However, further field trials are required to evaluate its effectiveness before it can be implemented in broader agricultural practices.