Silica Distribution in Kenya Roughages

Abstract

Silica has an almost universal occurrence in plants [1]. It has been found in this laboratory that whereas silica composes on average some7 per cent of the ash of lucerne (Medicagosativa) as this legume grows to maturation in the field, it composes on average over 17, 23,32, 37, 47 and 50 per cent respectively of the ash of Setaria sphacelata, Brachiaria ruziziensis,Cynodon dactylon, Chloris gayana,Melinis minutiflora and Hyparrhenia dissolutaas these grasses grow to maturation under similar circumstances. It has also been found in this laboratory that silica composes over 45per cent of the ash of the whole plant of barley and over 31 per cent of the whole plant of wheat as the two cereals grow to maturation in the field and that it composes over 32 and over 41 per cent respectively of the ash of the"heads" of barley and wheat from the time of their emergence to the time of ripening of the grain. The silica content of the dry matter of the whole barley plant increased from 1.1 percent in the young tissues to over 2 per cent at maturity and that of the whole wheat plant increased from just under 2 per cent to over6 per cent of the dry matter during the same period. The increase in the silica content of the dry matter of the whole wheat plant was directly and highly significantly related to the percentage of dry matter contained in the plant.