Unveiling the novel effect of Rhodopseudomonas palustris-derived extracellular 5-aminolevulinic acid on the growth and yield of  Chenopodium formosanum Koidz under field conditions

Abstract Background: Djulis is a nutrient-rich plant with potential health benefits, but its intensive fertilization hinders its yield, raising environmental concerns. Biofertilizers like purple non-sulfur bacteria (PNSB) offer an eco-friendly alternative to enhance growth and yield, yet limited research has investigated their efficacy on different djulis lines. Therefore, the current study aimed to investigate PNSB's effectiveness on two djulis lines in two fields, one control and the other inoculated with PNSB. Methods: Data on the growth and yield of djulis lines were collected and the results were statistically analyzed using independent sample t-tests and Duncan's multiple-range test. Results: The results showed that PNSB inoculation in the red line led to a significant increase in plant height (24%), leaf chlorophyll content (15%), spike length (35%), spike fresh weight (94%), shoot dry weight (207%), grain yield (86%), root length (119%), root volume (100%), and root dry weight (23%). As in the yellow line, PNSB inoculation significantly increased plant height (14%), spike length (26%), spike fresh weight (43%), shoot dry weight (53%), root length (36%), root volume (72%), and root dry weight (24%). Inoculation of PNSB had opposite effects on the maturity period of red and yellow djulis lines. It significantly improved the yield of the low-performing red line but had only minor effects on the high-performing yellow line, indicating the importance of selecting suitable lines. Conclusion: This study highlights PNSB's potential as a sustainable and cost-effective biofertilizer for djulis production and encourages further research to explore its applications in other crops and environments.