Potential Use of Microalgae Isolated from the Natural Environment as Biofertilizers for the Growth and Development of Pak Choi (Brassica rapa subsp. chinensis)

Biofertilizers derived from microalgae are increasingly used as promising materials for improving crop growth and development, producing fewer catastrophic environmental effects. Hence, the large-scale production of eco-friendly and broad-spectrum microalgae biofertilizers is mandatory. Therefore, this study was designed to examine the potential efficacy of isolated algae strains, such as Spirulina platensis, Spirulina maxima, and Chlorella vulgaris, to improve the growth and development of Pak Choi. A completely randomized design (CRD) was carried out, with five replications and six levels (0, 0.5, 1.0, 1.5, 2.0, and 2.5 g) of each microalga biofertilizer, using Pak Choi as the test plant. Treatment with microalgae biofertilizers was found to increase Pak Choi’s overall growth performance, biochemical development, and nutritional composition. The application of Spirulina platensis and Spirulina maxima microalgae at 2 g as a biofertilizer showed significant (p < 0.05) positive impacts on above- and below-ground biomass, photosynthetic parameters, biochemical composition, and the nutritional attributes of different parts of Pak Choi tissues. With the addition of biofertilizer, incorporating Chlorella vulgaris (2.5 g) showed remarkable (p < 0.05) impacts on the development of above- and below-ground biomass and biochemical and nutritional attributes. Thus, our results highlight that Chlorella vulgaris (2.5 g) outperforms other biofertilizer treatments and could be considered a sustainable approach for producing leafy vegetables.