### Phenological dynamics of N, P and K ecological stoichiometry in Chenopodium quinoa in Northwest Yunnan, China

LI zhaoguang, ,he guiqing,XU tiancai,HE qiongji,HOU zhijiang,LI yan,XUE runguang

1. Institute of Alpine Economics and Botany, Yunnan Academy of Agricultural Sciences
• Received:2021-06-15 Revised:2022-10-31 Published:2022-11-02
• Contact: XUE runguang

Abstract: Abstract Aims Nitrogen (N), phosphorus (P), and potassium (K) are key elements for plant growth and development. Exploring the ecological stoichiometry characteristics of N, P and K in the phenological stage is of great significance for understanding the physio-ecological processes such as nutrient limitation, resource absorption and utilization, and biomass allocation with the plant growth. Methods Here, we collected the roots, stems, leaves and spikes samples of Chenopodium quinoa in the differences phenological stage, and the tissue contents of nitrogen (N), phosphorus (P) and potassium (K) were examined. The differences of N, P and K contents and their ratios in the roots, stems, leaves and spikes of C. quinoa in their phenological stage, and their correlation with the biomass distribution ratios of various organs were analyzed. Important findings (1) The N contents of the roots, stems, leaves and spikes of C. quinoa were (9.28, 12.22, 33.68, 31.28) mg·g-1, P were (2.64, 3.71, 4.98, 5.68) mg·g-1, and K were (25.63, 43.80, 74.08, 56.73) mg·g-1, N:P were 4.66, 4.20, 7.37, 5.70, N:K were 0.39, 0.31, 0.46, 0.62, K:P were 13.77, 14.31, 16.82, 9.79, respectively. (2) The contents of N, P and K in roots, stems and spikes of C. quinoa and the contents of N and P in leaves decreased significantly with the passage of the phenological stage, which reflected the obvious dilution effect of the phenological stage. On the contrary, the K content of C. quinoa leaves increased significantly with growth, indicating an extremely strong drought resistance mechanism of C. quinoa under drought stress. The allocation ratios of N, P, K and biomass in the roots and stems of C. quinoa was relatively stable, while the allocation ratio in leaves decreased significantly, and the allocation ratios in spikes increased significantly, indicating that the key resource allocation regulation of leaves and spikes occurred during the flowering stage of C. quinoa. In the filling stage, the nutrient elements gradually transferred to the spike, and the biomass increased significantly. (3) According to the analysis of variation sources, the contribution of organs to N, K and N:P variation of C. quinoa was greater than that of phenological stage, and the contribution of phenological stage to the variation of P content in C. quinoa was greater than the difference among organs. (4) There was a tight coupling relationship between the allocation ratio of N, P and K and the allocation ratios of biomass among various organs of C. quinoa. Specifically, the allocation ratios of biomass in roots and leaves of C. quinoa has a significant positive correlation with the allocation ratios of N, P and K in roots and leaves, that significantly negatively correlated with the allocation ratios of spike N, P and K. The biomass allocation ratio of spike was only significantly positively correlated with its N, P and K allocation ratios, and significantly negatively correlated with the N, P and K allocation ratios of root and leaf. The results of this study will provide theoretical reference for further understanding of crop phenological character and guiding practical production in alpine regions.