Final answer:
An investigation to find the best concentration of plant growth substance for stimulating root growth involves comparing the effects of various concentrations of a hormone like auxin on plant cuttings planted under controlled conditions. Root growth is measured and analyzed to determine the optimum concentration promoting the best root development.
Step-by-step explanation:
To determine the best concentration of plant growth substances for stimulating root growth from a cut stem, one can carry out an experiment involving various concentrations of a plant hormone, such as auxin. The investigation should start with preparing cuttings of a plant species known to respond well to hormonal rooting treatments. Label different groups of cuttings and treat each group with a different concentration of auxin solution.
After treating the cuttings, plant them in a uniform medium like potting soil or sand, maintaining constant environmental conditions such as temperature, light, and humidity for all experimental groups. Over a specified period, observe and record the number of roots formed, the length of roots, and the overall health of the cuttings. Developing a control group with no added plant hormone is essential to compare the effects of the hormone accurately.
Data collected should be analyzed by counting and measuring the roots on cuttings from each concentration group to determine which concentration yields the optimum root growth. Statistical analysis can be used to confirm if differences between groups are significant. This way, the ideal concentration for promoting root growth can be concluded from scientific evidence gathered in the experiment.
By comparing the growth of roots at different concentrations, you can determine the best concentration of plant growth substance to stimulate root growth. Remember to conduct multiple trials to ensure reliability.