Establishment of maize seedlings. The transition from the skotomorphogenic or etiolation (heterotrophic growth) period to the photomorphogenic period (phototropic growth) is primarily regulated by growth of both the roots (PR, LR, and SR) and the mesocotyl. Growth of the roots and mesocotyl is controlled by several regulatory mechanisms, mainly tropisms and hormone signaling (M: mesocotyl, PR: primary root, SR: seminal root, LR: lateral root; LenR: root length of 80 and 120 mm; ME: mesocotyl elongation of 50 mm). Blue line: water requirements throughout phenological cycle of maize; yellow line: energy consumption of the seed.