The allelopathic effects of gibberellin on the growth of marine photosynthetic bacteria

摘要

We studied the effects of gibberellin (plant growth hormone) on the growth of photosynthetic bacteria (PSB). Gibberellin promoted the growth of PSB at an optimal concentration of 0.1 mg/L. In the presence of gibberellin, a deferred logarithmic growth phase appeared and lasted till the 24th days. In the primary logarithmic growth phase, the slopes of the fitted curves of the treated samples were 0.2605, 0.2335, 0.2362 and 0.2323 AU/day, while the slope of the control sample was 0.1879 AU/day, so the most significant growth promotion concentration was 0.1 mg/L. In the deferred logarithmic growth phase (7-24 days), the slopes of fitted curve were 0.0645,0.3337,0.3274 and 0.2817 AU/day, while the slope of the control sample was 0.0474 AU/day, so the most significant growth promotion concentration was 0.5 mg/L. The OD660nm results of growth promotion of PSB were put to statistical analysis with SPSS: It exhibited the notability otherness when the treated sample of 0.1 mg/L was compared with the control sample in 0-7 days (P<0.01). After 7 days, the concentration 0.5 mg/L produced the most significant promotion effect until the 24th day. Compared with the control sample, it exhibited the notability otherness (P<0.0l). Calculation results showed that, because gibberellin concentration increased 5 times, i.e., it became 0.5 mg/L from 0.1 mg/L, the quantity of PSB increased 5 times from the 7th day to the 24th day at the same time. The research will lay a good foundation for special selective concentration of plant hormone gibberellin in promotion culture of PSB. The growth promotion mechanism complied with receptor and second messenger theory of plant hormones and growth regulators. Therefrom, our researches entered the ecological field of interspecies reciprocity in aquatic environments, and this is the first report on the allelopathic effects of gibberellin on PSB.