The utilization of low-N tolerant and N-efficifent varieties offers significant benefits in terms of reducing the need for excessive N fertilizer input. Quinoa, a resilient crop for agroecological transition, possesses a wide genetic diversity, making it suitable for selecting genotypes that require less N fertilizer. In this study, the growth and physiological characteristics of nine quinoa genotypes were assessed to determine their low-N tolerance using the fuzzy membership function. Based on comprehensive evaluation indices, three genotypes were identified: low-N tolerant (BL22), intermediately tolerant (A29), and sensitive (G68). These genotypes were exposed to varying N concentrations, including normal (4 mM), low (0.8 mM), and deficient N (no N) conditions. The results indicate that low-N conditions altered root phenotype, with reduced biomass, total protein, and chlorophyll content; increased soluble sugar levels; and inhibited N-metabolizing enzymes (nitrate reductase, glutamine synthetase, glutamate synthase) and N uptake. Under low-N conditions, the tolerant genotype exhibited higher maximal efficiency of photosystem II (Fv/Fm), root vitality, and N content compared to the sensitive genotype. Interestingly, the sensitive genotype displayed elongated and thinner shoots and roots in response to low-N, suggesting that plant height and root length are unreliable indicators of low-N tolerance in quinoa. In contrast, shoot and root dry biomass, Fv/Fm, chlorophyll content, N-metabolizing enzymes, and N content proved to be reliable indicators of low-N tolerance during the early growth stage of quinoa. Overall, these findings highlight the potential of utilizing specific growth and physiological parameters as indicators for screening low-N tolerant quinoa genotypes, thereby reducing dependence on N fertilizers.

To explore the efficiency of selenium (Se) fertilizer application in dryland maize, we tested five Se fertilizer application treatments: 0 g ha⁻¹ (Se0), 75 g ha⁻¹ (Se1), 150 g ha⁻¹ (Se2), 225 g ha⁻¹ (Se3), and 300 g ha⁻¹ (Se4). Compared with Se0, Se2 increased the leaf area, chlorophyll content, internode length, plant height, and ear height by 7.95%, 3.20%, 13.19%, 1.89%, and 7.98%, respectively. Se2 and Se3 significantly affected the stem internode diameter, cortex thickness, and cellulose content, which were positively correlated with lodging resistance. Compared with Se0, Se3 promoted the contents of soluble sugar, crude protein, crude fat, and starch in grains, which increased by 9.48%, 6.59%, 1.56%, and 4.82%, respectively. It implies that maize grain application of Se significantly improves their Se content. Se1 did not observably influence the growth of maize, and the promoting effect of Se4 on maize decreased. The lodging resistance of maize as analyzed by Pearson correlation analysis correlated with the application of Se fertilizer. It proved that higher yield, grain quality, grain Se content, and lodging resistance of stems were concerned with Se fertilizer application in the range of 150–225 g ha⁻¹. The results provide useful information for Se fertilizer treatment in dryland maize.

To explore the suitable cultivation and management model of quinoa in northern Shanxi province, and therefore improve the yield and quality of quinoa, an experiment was conducted with cultivar Huaqing 1 as plant material. The effects of varied proportion of organic and inorganic fertilizer on the growth process of quinoa, agronomic traits, yield, and quality were studied using single factor completely random design. There were three treatments including T1 (1500 kg hm ^-2 organic fertilizer, 225 kg hm ^-2 each for urea and diamine phosphate), T2 (2250 kg hm ^-2 organic fertilizer, 225 kg hm ^-2 each for urea and diamine phosphate), and T3 (3000 kg hm ^-2 organic fertilizer, 225 kg hm ^-2 each for urea and diamine phosphate), conventional fertilization (0 kg hm ^-2 organic fertilizer, 450 kg hm ^-2 each for urea and diamine phosphate) was the control. The results showed that the combined biological bacterial fertilizer and inorganic fertilizer could increase the content of organic matter, available nitrogen, phosphorus, and potassium in soil, and decrease the pH of soil. Compared with CK, the combined biological fertilizer could effectively shorten the growth period, and increase plant height, stem diameter and stem strength at mature stage, thus reduce lodging rate. Also, combined biological fertilizer treatment promoted the branches and 1000-grain weight of quinoa, and improved quinoa yield, protein content and fat content, and the above favorite effects were obviously showed in T2 treatment. Starch content was the lowest in T2 treatment, but there was no significant differences among the three treatments. With the increase application of bacterial fertilizer, nitrogen use efficiency, phosphorus fertilizer use efficiency and partial productivity of nitrogen and phosphorus fertilizer was firstly increased and then decreased. Among three groups, the above index was the highest in T2 treatment. Correlation analysis showed that the relationship between the yield and 1000-grain weight was the most correlated, and protein content in grains was positively correlated with yield, 1000-grain weight, branch number, and stem strength, but negatively correlated with lodging rate. In conclusion, under the condition of current experiment, the suitable nitrogen application rate for quinoa was the combination of urea (225 kg hm ^-2), diamine phosphate (225 kg hm ^-2) and inorganic fertilizer (2250 kg hm ^-2).

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.