Modulation of seed dormancy in Ocimum basilicum by light, gibberellins (GA3) and abscisic acid (ABA)

摘要

Ocimum basilicum L. (Lamiaceae), a common annual weed in central Sudan, is problematic in all crops in the area as it displays no seasonal periodicity in germination and is tolerant to most herbicides. The present study investigated the effects of light, gibberellins (GA3) and abscisic acid (ABA) on germination under a constant temperature of 30°C. The weed did not germinate in the dark. In continuous light, maximum germination (> 95%) was displayed on imbibition in water for 2 days. Germination increased with light duration. Exposure to light for 3, 12 and 21 h induced 8, 48 and 90% germination within 3 days. The light induced germination was inhibited by paclobutrazol (a gibberellin biosynthesis inhibitor). GA3 induced germination in the dark andalleviated, completely, the inhibitory effects of paclobutrazol. ABA reduced and delayed germination. GA3 mitigated the inhibitory effect of ABA. The results, which are consistent with a model in which light induced germination by promoting GAs biosynthesis and ABA catabolism, suggest that deep ploughing and husbandry practices that promote rapid canopy closure may reduce O. basilicum infestation in field crops.