Grain filling 11 to 16 days

Whole grain photographs


Dorsal view of the whole grain at the medium milk stage. This is the start of the grain filling stage. The grain is about 8mm long, easily squashed with a thumbnail and contains a thin milky liquid.
An individual spikelet 16 days after pollination. floret 1 has been cut away and its component parts are separated. Developing grains are found in floret one and floret two but only rarely in the upper florets.
Here the epidermis and the maternal pericarp have been dissected away. The mint green colour of the pericarp is diagnostic at this stage. The green colour comes from chloroplasts in the 'cross cell' layer. The embryo is about 1mm long and is still quite easy to dissect out.
Longitudinal section of the fresh grain through the ventral groove. The thick walled cells of the ventral groove become the 'modified groove aleurone', these cells are responsible for the uptake of assimilates during the grain filling period. The aleurone cells on the dorsal side of the grain behave differently.
Transverse section of the fresh grain at the start of grain filling. The outer clear maternal epidermis loosely covers the pericarp and allows light to penetrate. As the endosperm packs with starch the outer layers will become stretched and crushed.