発芽 and 芽: germination, a soil sprout and a branch bud
Read 発芽 and 芽 through soaked beans sprouting, a sprout emerging from soil and branch buds swelling. Separate the observed result, investigation and gradual change.
発芽 as germination and an investigation
発芽 (はつが) means germination or sprouting. 「水に浸した豆が三日後に発芽した。」 means “The soaked beans sprouted after three days.” Three days is the timing stated for these beans, not a fixed germination period for every seed.
「種子の発芽に必要な条件を実験で調べた。」 means “We investigated the conditions needed for seed germination.” The Japanese 実験で places the investigation in an experiment, while the English translation emphasizes investigating the conditions. Neither supplies a complete set of established conditions or a new successful outcome.
芽 as a sprout or a bud
芽 (め) can mean a sprout or a bud. 「植木鉢の土から小さな芽が出ました。」 means “A small sprout emerged from the potting soil.” This sentence reports the emergence of a small sprout from soil.
「春が近づくと枝の芽が少しずつ膨らみます。」 means “As spring approaches, the buds on the branches gradually swell.” The buds are on branches, and gradual swelling is linked to spring approaching. This does not report that flowers or fruit have already formed.
A named object and the change it undergoes
発芽した describes the beans sprouting, whereas the 芽 examples name the sprout that emerged and the buds that swell. Read the change separately from the object undergoing it.
枝の芽 and 少しずつ膨らむ identify branch buds and their gradual swelling. Treating every 芽 as a seed's newly germinated sprout would replace the object described in this example.
Must 芽 in 枝の芽が少しずつ膨らみます be a sprout from a seed that has just germinated?
Show the answer and why
No. It refers to buds on branches gradually swelling. Keep this separate from the soaked beans that sprouted after three days and the sprout emerging from potting soil. The sentence does not say that flowers or fruit have already formed.