0 in plants with flowers, a hard layer that covers and protects the surface of a seed -- 外种皮（覆盖和保护种子表面的硬皮）
From a small area of the dry seed surface the testa was removed and 5 mg of flour was scratched from the cotyledons.
Small bites had been taken from another seed although there was no evidence that the testa had first been removed.
I suggested a mechanical function of the testa.
The mutant 20-dpa testa did not stain blue (instead it stained purple), and hypodermal cells were not reticulated (data not shown).
A slow rate of ethylene production was found in these seeds, the testa being the source.
The completion of germination was defined as the radicle visibly protruding from the testa.
The molecular data presented here are consistent with the anatomical and biochemical differences between the wild-type and the mutant testae.
Progress of testa rupture is facilitated by channels underlying the ridges.
