Effects of various types of phosphorus fertilizer on growth, yield, and phosphorus absorption characteristics in buckwheat

Abstract

This study was conducted to clarify the characteristics of phosphorus absorption in buckwheat (Fagopyrum esculentum Moench) and to elucidate the reasons for low seed yield in Kunigami-maaji soil cultivation. Buckwheat growth and seed yield were drastically suppressed in the treatment with no phosphorus fertilizer. At harvest time, root dry weight in the low-phosphorus condition was larger than that in the high-phosphorus condition, as root growth was promoted or prolonged after the flowering stage, which seemed to lead to greater nutrient absorption in the low-phosphorus treatment. In addition, both the concentrations and uptakes of phosphorus in the leaves and stem decreased after the flowering stage, while the phosphorus concentration in seeds remained around 2.5 g/kg in the low-phosphorus condition. Thus, it appears that the phosphorus in leaves and stem is remobilized to the seeds after the flowering stage to keep the seed phosphorus concentration at that level. These two phosphorus-absorption characteristics of buckwheat seem to underlie the crop’s tolerance of low phosphorus. Furthermore, our experiments also revealed that the decrease of growth and yield was severe when buckwheat was cultivated with Fe-bound phosphorus, whereas the decline was small with Al-bound phosphorus.