Objective  Effects of phosphate (P) fertilizer on the soil fertility and the plant morphology, available nutrients, and grain yield and quality of common buckwheat, Fagopyrum esculentum, were investigated.

  Method  A high yield buckwheat, Fengtian 1 (FT1), was cultivated under P fertilization at 0 kg·hm⁻² P (CK), 35 kg·hm⁻² P (LP), 70 kg·hm⁻² P (MP) or 105 kg·hm⁻² P (HP). Effects of the fertilizations on the soil nutrient contents as well as the root morphology, aboveground botanical characteristics, and yield of the buckwheat plants were determined.

  Result  The increased P fertilizer applications enhanced the contents of available nutrients and organic matters in soil with a peak under MP. But the soil pH was on a continuous downward trend upon increasing P. For the plants, the root length, volume, and surface area reached their highest levels with MP as well. However, the root diameter was not significantly affected by the changes on the application. Morphologically, the plant height, node and branch numbers on main stems, 1- to 2-internode length, 1- to 2-internode diameter, and grain yield increased significantly under MP, much more than the other treatments. Again, the higher P in HP did not render further increases as MP did. Among all treatments, MP also delivered the greatest grain yield, which was 1.43 times that of CK. Similarly, the contents of protein, dietary fiber, rutin, quercetin, and kaempferol of the FT1 grains rose along with the increasing P application up to the level in MP. On the other hand, the flavonoid in the grains reached the highest level under CK and the lowest under HP.

  Conclusion  It appeared that P fertilization in the amount of MP would be appropriate for the growth, grain yield and quality of FT1 plants.