Light, dark and growth regulator involvement in groundnut (Arachis hypogaea L.) pod development

Gynophore elongation and pod formation were studied in peanut plants (Arachis hypogaea L.) under light and dark conditions in vivo. The gynophores elongated until pod formation was initiated. Pod (3-20 mm length) development could be totally controlled by alternating dark (switched on) and light (switched off) conditions, repeatedly. Gynophore elongation responded conversely to light/dark conditions, compared to pods. In this study we aimed to correlate the light/dark effects with endogenous growth substances. The levels of endogenous growth substances were determined in the different stags of pod development. Gynophores shortly after penetration into the soil, 'white' gynophores, released twice the amount of ethylene as compared to the aerial green ones, or to gynophores bearing pods. Ethylene inhibitors had no effect on the percent of gynophores that developed pods, but affected pod size which were smaller compared to the control. A similar level of IAA was extracted from gynophore tips of green gynophores, 'white' gynophores and pods. ABA levels differed between the three stages and were highest in the green gynophores and lowest in the pods.