Conclusion

 

The initial hypothesis was supported by the collected data. According to the data, the two plants that were watered with the highest concentration of NaCl had the lowest transpiration rates and actually gained mass over the testing period. The other four plants had higher transpiration rates as they lost mass consistently over the testing period. The plant watered with distilled water consistently lost about 5 grams a day while the plant with 0.3M NaCl lost about 3 grams a day. The distilled water serves as the control and so the experimental results show that transpiration rates decrease as the concentration of NaCl increases. The gradient of water potential from the stem to the leaf was also affected by the independent variable. Adding solutes to water lowers the water potential and so with each successive level of the independent variable the water potential was lowered.

 

When performing this experiment, the solutions had to be made by mixing certain amounts of pure NaCl to distilled water. Thus, the accuracy of the analytical balance used determines the accuracy of the concentrations in the experiment. Additionally, some of the plants were placed closer to a light source than others as shown in the experimental set up. Plants closer to the light source could have had higher rates of photosynthesis and change the collected masses. 10 mL of water was used to water the plants each day using small, 1 mL pipettes.

 

The accuracy of the amount of water used is thus dependent on the accuracy of the pipettes used. To improve this experiment, it could be repeated multiple times to obtain more accurate data. Additionally, different species of plants could be used to see the consistency of salt effects on plants in general. A wider range of concentrations used with smaller subintervals to water the plants would also more clearly depict the effect of salt concentration on transpiration rates. Different types of salts could also be used in the experiment to see how consistent the effect of salt is generally on transpiration rates.

 

Future Research: 

 

Title: The Effect of Drought Tolerance in Plants on Transpiration Rates

Hypothesis: If drought tolerant plants and non-drought tolerant plants were massed before and after being watered, then the non-drought tolerant plants would experience higher rates of transpiration. 

Purpose: To determine the effects of drought tolerance on transpiration rates

 

 

 

 

 

D.V. : Transpiration Rate

Constants: Sunlight, soil, temperature, humidity, & wind

Control: Non-Drought Tolerant 

 

Predictions; It can be predicted that the drought tolerant plants will have lower transpiration rates because they have the mechanisms that allow them to adapt to the change in environment. The non-drought tolerant plants will become dehydrated from too much transpiration because they lack these mechanisms.