8.12—Core Practical 18 - amylase in germinating cereal grains

During germination, gibberellin signalling stimulates aleurone cells to produce amylase. Amylase hydrolyses starch in the endosperm to soluble sugars that the embryo can respire and use for growth.

Compare germinating and non-germinating grains or vary a condition while controlling temperature, water and time. Measure reducing sugar or iodine-starch change with suitable repeats and controls.

A grain with active amylase loses the blue-black iodine colour as starch falls and gains soluble sugar; that sugar supports respiration rather than being “new starch”.

Iodine detects starch, not amylase directly, and a colour change needs a controlled comparison. Do not infer enzyme activity from germination alone.