Investigating the quality of quinoa (Chenopodium quinoa Willd.) seed under the influence of different levels of irrigation and vermicompost

Quinoa ( Chenopodium quinoa ), a globally sought-after crop for its nutritional value and adaptability, faces increasing demands for sustainable cultivation practices. This two-year study, conducted at the Research Farm of the University of Kurdistan, Iran (2021–2022), investigated the impact of varying irrigation levels and vermicompost application on quinoa yield and seed quality, aiming to reduce chemical fertilizer dependency. The experiment utilized a split-plot based on a randomized complete block design. Four irrigation levels (50%, 75%, 100%, and 125% of quinoa's water requirement) constituted the main factor, while four vermicompost application rates (0, 5, 10, and 15 tons per hectare) formed the sub-factor. The results showed that the 125% water requirement treatment achieved the highest seed yield (2131.51 kg ha ^− 1 ) and biological yield (4975.10 kg ha ^− 1 ), while the 15 tons per hectare vermicompost application resulted in significant yield improvements, reaching 1784.01 kg ha ^− 1 for seed yield and 4100.25 kg ha-1 for biological yield. Notably, the highest nitrogen concentration (2.54%) in quinoa seed was observed in the second year with 15 tons per hectare of vermicompost and 50% of the water requirement. Furthermore, the application of 15 tons per hectare of vermicompost led to a 54% increase in phosphorus, 51% increase in potassium, and a 23.79% increase in seed calcium compared to the control treatment. This study highlights the potential of vermicompost and optimized irrigation levels to significantly enhance quinoa yield and improve the nutritional profile of quinoa seeds. These findings promote sustainable agricultural practices by minimizing reliance on chemical fertilizers while optimizing resource utilization.