Studies on the histology and colouration of the pericarp of the sorghum grain

Abstract

1. The histology of the pericarp of wild and cultivated races of sorghum have been described. 2. The organogeny of the pericarp has been studied. The tube cells were found to arise from the inner epidermis of the pericarp while the integument was from the inner integument and not from the nucellus. The latter is completely absorbed. 3. The wild sorghums are characterised by a very thin pericarp consisting of only epidermis and tube cells and sometimes a very small tissue of mesocarp. An integument is always present. All wild sorghums are brown coloured. 4. The cultivated sorghums have similar layers to the wild ones but the number of layers is greater. The grains could be distinguished into two main groups (i) starchy and (2) non-starchy. The integument is found only in some grains and absent in all others. The grains with the integument are generally brown. 5. The colour of the pericarp is found mostly in the epidermis, hypodermis and the tube cells. The integument is always coloured brown and the tube cell is also coloured similarly whenever an integument is present. The mesocarp is rarely coloured. 6. An examination of the F1 and parents of some of the crosses revealed that while both the parents had no integuments at all, the F1 had an integument indicating complementary factors. 7. On examination of pseudomutation grains and grain chimera it was seen that whenever there was a brown colour there was an integument present and absent when the grain was not brown.