Complex sentence: Corn was used as raw material in much of the synthetic rubber produced during the war, and various other plants, including guayule and kok-saghyz (Russian dandelion), were investigated as rubber sources.
Split into simpler sentences: Corn was used as raw material in much of the synthetic rubber produced during the war. Various other plants, including guayule and kok-saghyz (Russian dandelion), were investigated as rubber sources.