The Effects of Auxin and Gibberellin on Germination and Growth of Lactuca Satira Seeds

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The Effects of Auxin and Gibberellin on Germination and Growth of Lactuca Satira Seeds


The effects of hormones on plants vary depending on the hormone, concentration, and plant that it is influencing. Some hormones stimulate growth at some certain concentrations but inhibit growth at other concentrations. Gibberellic acid and auxin were both tested at five different concentrations: 50, 5, 0.5, 0.05, and 0 ┬Ám. Ten total petri dishes were used with ten Lactuca Sativa seeds in each dish. A different hormone concentration mixture was added to each of the ten petri dishes. Then the petri dishes were placed in a dark drawer for a week to germinate. The hypothesis stated that since auxin and gibberellic acid both stimulate plant growth, then the Lactuca Sativa seeds would germinate at a quicker pace as the concentrations increase. This being said, as hormone concentration increases, growth of the entire plant would increase as well. However, we found that this was not necessarily the case because as hormone concentration increased, plant growth did not increase proportionally. Plant growth was random and seemed to have no direct association with hormone concentration. The hypothesis also stated that there would be a greater effect on stem growth than on root growth when using either hormone. We found that this did seem to be general trend in our data possibly due to the different type of meristematic tissue found in the stem verses the root.


Plant hormones occur naturally and can stimulate or inhibit plant growth. Naturally, these hormones are required in very small amounts and their concentrations vary depending on the plant and the tissue (Srivastava 2002). Effects of plant growth also depend on the hormone that is being used. Auxins and gibberellins are very similar to one another as they both stimulate plant growth by promoting cell division and elongation, mostly in the stem (Peters 2004). However, it is thought that depending on the...