In this study, 300 quinoa accessions were systematically screened for adaptation to low-altitude areas using seventeen traits. The experiment was conducted in Taigu District, Jinzhong City, Shanxi Province, in 2021, at an altitude of 791 m. Out of the 300 genotypes, 107 were able to produce flowers and fruit, with yields ranging from 538 to 5132 kg ha⁻¹ and with 1000-grain weights between 1.19 g and 2.37 g. These 107 quinoa genotypes were categorized into four groups based on grain yield: below 1500, 1500–2250, 2250–3000, and above 3000 kg ha⁻¹. These groups consisted of 33, 33, 24, and 17 genotypes, respectively. This study found that the 1000-grain weight ranged from 1.19 g to 2.37 g, with an average of 1.72 g, 1.72 g, 1.83 g, and 1.92 g for the respective yield levels. Among the 107 genotypes, 25 had a 1000-grain weight exceeding 2 g, and 13 of these genotypes also had yields exceeding 2250 kg ha⁻¹. The growth period of quinoa genotypes in the low-altitude area was approximately 138–142 days, with longer growth periods associated with higher yield levels. JQ-00084 is the only genotype with a yield > 3000 kg ha⁻¹ and meets all the growth criteria, including a 1000-grain weight exceeding 2 g and a flowering-to-maturity period of over 80 days. Meanwhile, JQ-00315, JQ-00521, JQ-1029, and JQ-02405 fulfilled at least four criteria. These results highlight the importance of germplasm screening for low altitudes, and a large set of germplasms could be screened using the above criteria of phenology, growth, and yield traits.

This study aims to understand the influence of nitrogen accumulation, fungal endophyte, yield, nitrogen use efficiency, and grain nutritional quality parameters on the yield of quinoa in some areas of China. The endophytic microbial community in plants plays a crucial role in plant growth, development, and health, especially in quinoa plants under different nitrogen fertilizer levels. The results from the present study indicated that appropriate nitrogen application significantly enhanced the nitrogen accumulation and yield of quinoa grains during maturity, increasing by 34.54–42.18% and 14.59–30.71%, respectively. Concurrently, protein content, amylose, total starch, ash, and fat content also increased, with respective growth rates of 1.15–18.18%, 30.74–42.53%, 6.40–12.40%, 1.94–21.94%, and 5.32–22.22%. Our constructed interaction network of bacterial and fungal communities revealed that bacteria outnumbered fungi significantly, and most of them exhibited synergistic interactions. The moderate increase in N150 was beneficial for increasing quinoa yield, achieving nitrogen use efficiency (NUE) of over 20%. The N210 was increased, and both the yield and NUE significantly decreased. This study provides novel insights into the impact of nitrogen fertilizer on quinoa growth and microbial communities, which are crucial for achieving agricultural sustainable development.

Background: Quinoa (Chenopodium quinoa Willd.), valued as a nutrient-dense grain, has seen expanded cultivation in China. However, its yield and quality are often unstable due to suboptimal fertilization practices, and the specific regulatory roles of macronutrients (N, P, K) remain unclear. This study aimed to elucidate the effects of combined NPK fertilization on the growth, yield, and nutritional quality of quinoa. Methods: A pot experiment was conducted in a controlled climate chamber using the “Jingli 1” cultivar. Plants were subjected to four fertilization treatments: NPK, PK, NK, and NP. Results: The NPK treatment significantly enhanced growth throughout the development cycle, increasing total root length (45.0±8.5%), root surface area (32.8±6.2%), plant height (20.0±5.0 cm), and dry matter accumulation (71.6±15.3%). It also improved nitrogen use efficiency and key yield components, including panicle length (5.63±1.22 cm), thousand-grain weight (0.34±0.02 g), and grain weight per plant (1.41±0.23 g). Nutritionally, the NPK treatment elevated the content of essential amino acids (284.10±52.75 mg/g), total free amino acids (2414.65±428.30 mg/g), and increased levels of protein, starch, and fat. Deficiency analyses revealed distinct limitations: nitrogen deficiency primarily constrained aboveground growth and yield; phosphorus deficiency strongly inhibited root development and dry matter accumulation; while potassium deficiency had comparatively minor effects. The synergistic application of NPK fertilizers is crucial for optimizing quinoa production. It promotes robust root and shoot growth, enhances nitrogen uptake, and simultaneously achieves high yield and superior nutritional quality, providing a scientific basis for optimized quinoa cultivation practices.