Introduction: Buckwheat (Fagopyrum tataricum), an important food crop, also has medicinal uses. It is widely planted in Southwest China, overlapping with planting areas remarkably polluted by cadmium (Cd). Therefore, it is of great significance to study the response mechanism of buckwheat under Cd stress and further develop varieties with excellent Cd tolerance.Methods: In this study, two critical periods of Cd stress treatment (days 7 and 14 after Cd treatment) of cultivated buckwheat (Pinku-1, named K33) and perennial species (F. tatari-cymosum Q.F. Chen) (duoku, named DK19) were analyzed using transcriptome and metabolomics.Results: The results showed that Cd stress led to changes in reactive oxygen species (ROS) and the chlorophyll system. Moreover, Cd-response genes related to stress response, amino acid metabolism, and ROS scavenging were enriched or activated in DK19. Transcriptome and metabolomic analyses highlighted the important role of galactose, lipid (glycerophosphatide metabolism and glycerophosphatide metabolism), and glutathione metabolism in response to Cd stress in buckwheat, which are significantly enriched at the gene and metabolic levels in DK19.Discussion: The results of the present study provide valuable information for a better understanding of the molecular mechanisms underlying Cd tolerance in buckwheat and useful clues for the genetic improvement of drought tolerance in buckwheat.

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.

Exogenous selenium application could effectively improve the selenium absorption of crops affected by different climatic conditions due to changes in the planting environment and planting conditions. We planted maize at planting densities of 67,500 plants ha⁻¹ (D1) and 75,000 plants ha⁻¹ (D2). Five selenium fertilizer gradients of 0 mg m⁻² (Se0), 7.5 mg m⁻² (Se1), 15.0 mg m⁻² (Se2), 22.5 mg m⁻² (Se3), and 30.0 mg m⁻² (Se4) were applied to investigate the response of the plants to selenium fertilizer application in terms of the gradient selenium absorption and substance accumulation. With the increase in the amount of selenium fertilizer applied, more of the selenium fertilizer will be absorbed and transported from the leaves to the grains, and the selenium content of the grains will gradually increase and exceed the selenium content of leaves. Under the D2 density in 2022, the selenium content of the grains under Se1, Se2, Se3, and Se4 treatments increased by 65.67%, 72.71%, and 250.53%, respectively, compared with that of Se0. A total of 260.55% of the plants showed a gradient of grain > leaf > cob > stalk from the Se2 treatment, and the overall selenium content of the plants increased first and then decreased. Under the D1 density, compared with the Se0, the dry matter mass of the Se1, Se2, Se3, and Se4 treatments significantly improved by 5.84%, 1.49%, and 14.26% in 2021, and significantly improved by 4.84%, 3.50%, and 2.85% in 2022. The 1000-grain weight under Se2, Se3, and Se4 treatments improved by 8.57%, 9.06%, and 15.56% compared to that under the Se0 treatment, and the yield per ha under the Se2, Se3, and Se4 treatments was 18.58%, 9.09%, and 21.42% higher than that under Se0 treatment, respectively. In addition, a reasonable combination of selenium application rate and density could improve the chlorophyll content and stem growth of dryland maize. This lays a foundation for the efficient application of selenium fertilizer and provides an important reference.