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 evaluate
the effect of breeding and growing conditions on the structure and
degradability of lupin seed coats. Breeding has had significant influences on
both seed size and seed coat structure of lupins. For instance, cultivars of
Lupinus 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. angustifolius.
Hardseeded and roughseeded lines of L. cosentinii had
thicker coats (P < 0.05) than softseeded and
smoothseeded, respectively. The main contributor 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 and inner parenchyma. Anatomical analysis
revealed that the soft seed coat tended to have short and round cells, whereas
the hard seed tended to have long cells in the palisade layer. Smooth seeds
had round cells in the subpalisade, but rough seeds had long cells in this
layer. Although the seed coats of lupins contained about 80% crude
fibre, with L. cosentinii and
L. pilosus having more fibre than
L. angustifolius, the fibre in lupin seed coats was
highly digestible by sheep.
Selection for recombination in a polygenic model – the mechanism
