Effect of Calcium Nutrition on the Formation of Calcium Oxalate in Kikuyu Grass

17-45 ABSTRACT The objective of this investigation was to study the formation of calcium oxalate crystals in situ in kikuyu grass (Pennisetum clandestinum) and to determine the effect of calcium uptake on the soluble and insoluble oxalate content of the grass. Oxalate crystals were more abundant in high-calcium leaves than in low-calcium leaves. Electron microscopy showed that the oxalate crystals are formed in association with globular electron-dense bodies in the vacuole of certain cells. The calcium content of kikuyu is increased by increasing the calcium level of the growth medium. However, the increased amount of calcium taken up by the plant is largely bound as insoluble calcium oxalate, which is poorly available to the grazing animal.