Abstract
Orchardgrass (Dactylis glomerata L. CV. Aonami) was grown under the different potassium levels by water culture method and the growth response to potassium was investigated. The results were as follows; The plant growth and the potassium concentration in orchardgrass clearly responded to the potassium, although the response distinctly depended on the different levels of potassium in culture solution. In the lower potassium levels, there was a significant increase of the plant yield with increase of potassium level without any change of potassium concentration in plant, while in the higher levels there was a significant increase of potassium concentration in plant with increase of potassium level without any increase of plant yield. Moreover in the excessive levels of potassium in culture solution, plant growth and potassium uptake were restricted. The potassium concentration in the plant well responded to the increase of fresh yield until it reached up to 3 per cent of potassium on a dry matter basis, while the higher concentrations than 3 per cent of potassium did not result in the increase of plant growth. It was clearly recognized that the excessive increases of potassium concentration in the plant resulted in the decrease of calcium and magnesium concentrations in the plant.
