Studies of the chemical composition of kales and rapes. I. The kales

Abstract

1. Four varieties of marrow stem kale, three of thousand headed kales, Hungry Gap Kale and Rape-Kale were grown at three centres in mid-Wales. They were sampled in the early winter period and separate leaf and stem samples analysed for the proximate constituents and minerals.2. Leaf to stem ratios were measured on both a green and dry matter basis and the latter values used to calculate whole plant values for the chemical constituents.3. The leaves of the marrow stem kales were higher in dry matter than the stems, except in the case of the Purple Stem Kale. This variety resembled the thousand headed and rape-type kales in having a higher dry matter in the stems. On a dry matter basis, the leaves of all the varieties were richer than the stems in ether extract, crude protein, total ash and all the minerals except potassium and sodium. These elements occurred to a greater extent in the stems of the fleshy stemmed marrow stem kales than in the leaves. The stems were higher in crude fibre and nitrogen-free extractives.4. The leaves of the rape-type kales were higher than those of the other varieties in silica, phosphorus and potassium. They were the best source of phosphorus on a whole plant basis. The marrow stem kales had considerably higher leaf and stem values for sodium and were markedly superior to the other varieties as a source of the element.