Anatomical structure and nutritive value of lupin seed coats

Selection and breeding for yield and adaptation to environmental conditions often changes a number of characteristics of crops, and may influence the value of seed for animals. A series of experiments was conducted to evaluat e the effect of breeding and growing conditions on the structure and degrad ability of lupin seed coats. Breeding has had significant influences on bot h seed size and seed coat structure of lupins. For instance, cultivars of L upinus angustifolius released in 1987 and 1988 tended to have smaller seeds with a thicker seed coat than those released in 1971 (P < 0.05). Selection for soft seeds has resulted in a reduction of seed coat thickness in L. an gustifolius. Hardseeded and roughseeded lines of L. cosentinii had thicker coats (P < 0.05) than softseeded and smoothseeded, respectively. The main c ontributor to the thick seed coat of hardseeded lines was a layer of cells known as the hourglass layer, which is located between the outer palisade a nd inner parenchyma. Anatomical analysis revealed that the soft seed coat t ended to have short and round cells, whereas the hard seed tended to have l ong cells in the palisade layer. Smooth seeds had round cells in the subpal isade, but rough seeds had long cells in this layer. Although the seed coat s of lupins contained about 80% crude fibre, with L. cosentinii and L. pilo sus having more fibre than L. angustifolius, the fibre in lupin seed coats was highly digestible by sheep.