pH 9 plants also had a slow and steady increase (graphs 1-9). It can be seen in graph 10 the average growth of plants, beginning at pH 3 and ending at pH 9, the height is increasing steadily from pH 3 to pH 5 and then maximum height is reached at pH 7. The height then begins decreasing slowly after pH 7 to pH 9. This once again supports the research, in which plants grow best at a pH between 7 and 9. Due to the optimum pH for photosynthesis being 8, thus the optimum pH for photosynthesis met and enables maximum growth of the plants. It can be seen in table 11, that total growth of all 18 plants.
This was calculated by subtracting the initial height from the end height, thus giving the total growth over the three week period. It is clearly evident that pH 7 plants had the highest total growth as the four plants watered with pH 7 had the following total growth; 4. 3, 3. 1, 3. 3, 5. 2. The total growth of plants that received pH 7 by far had the most growth. pH 9 plants had the second highest total growth, followed by pH 5 and then pH 3. In summary, from the results it is clearly evident that the broad-bean plants that were watered with a pH 7 solution had the largest rate of growth.
Over the three week period in which the experiment was conducted, the average height of the pH 7 plants was 8. 11cm. It is apparent from the data in tables one to nine that the pH 7 plants grew more abundantly and steadily. Graph one also clearly illustrates that the rate of growth reaches its peak at pH 7 and begins slowly declining afterwards; indicating that pH 7 was the optimum pH for these plants to grow. However the broad-bean plants that were watered with pH 9 solution also had a large growth rate following closely behind pH7. The average height of the plants watered with pH 9 was 7. 84cm, only 0. 27cm less than the pH 7 height.
However, because pH 9 is at end of the optimum pH range for these plants to grow, the plants did not grow as high as pH 7. This is for the reason that plants grow best between pH 7 and pH 9. The broad-bean plants that were watered with pH 7 and pH 9 had a large growth rate because they were able to acquire the nutrients the plant needed. More importantly because these particular plants were watered with a pH 7 or 9 which is the optimal pH for these plants, the enzymes involved in photosynthesis was also receiving its optimum pH and could therefore carry out the chemical reactions in the cell, including photosynthesis.
It is also evident that pH 3 and pH 5 dramatically reduced plant growth, as on average plants watered with pH 3 had a height of 6. 16 and plants watered with pH 5 had an average height of 6. 50 lower growth rate. This is because pH 3 and pH 5 are well below the optimum pH needed for these plants to grow adequately. Therefore the plants do not receive the nutrients they need to grow nor do the enzymes that catalyse the chemical reaction for photosynthesis to occur, thus growth is stunted.
Thus hypothesis one stating that if the pH is neutral, the growth of the plant will increase because the maximum availability of primary nutrients required for plant growth is greatest at a pH value between 7 and 9 is supported by the results. The experiment findings did provide the expected results; however, the accuracy of the data collected is of a low standard. To obtain more accurate results in the future, the plants should be the same height as each other at the start of the experiment or as be as close as possible. As the heights at the start of the experiment were so different (they ranged from 1.
5-12. 7), the results are not as accurate as they could have been, if the range of heights were not so different. Another fault which depletes the accuracy of the results of the experiment is that inaccurate measuring tools such as plastic rulers were used to measure the plants heights. The ruler used was not very accurate, the zero did not line up with the base of the plant. Also, where the plant ended was very subjective as the stem of the plants may have been lower in the soil, however, if plant was dug around to obtain a more accurate reading this would disrupt the plant thus affecting the results.
A more accurate measuring system would be needed in future in order to achieve more precise results. The data gathered from this experiment is very relevant as the results obtained show the degree of usefulness of pH for maximum plant growth. For gardeners and farmers when growing plants and produce it is important to know what level of pH will enable them to have maximum plant growth. This experiment is extremely relevant as it shows that pH 7-9 results in larger and steadier plant growth.
As these results show a very substantial difference in the growth rate of plants watered with pH 3 and 5 and pH 7 and 9 in such a short period of time, this experiment could benefit gardeners and farmers immensely as they have the knowledge to maximise their plant growth. It is therefore an extremely relevant experiment and should be repeated over a longer period of time to obtain more accurate results. After acquiring information from this investigation, it is possible for further investigations to be conducted continuing on from the above findings.
Firstly, an investigation into the use of different amounts of pH 7 to determine if pH 7 could have a negative effect on plant growth if received in small or large amounts. Secondly, investigate how 9. 0 Conclusion In conclusion, in completing this experiment it was found that the results did in fact support the formulated hypotheses. Firstly, that if the pH is neutral, the growth of the plant will increase because the maximum availability of primary nutrients required for plant growth is greatest at a pH value between 7 and 9.
Secondly, if the pH is acidic (pH 1-6) then the growth of the plant will decrease because of availability of primary nutrients required for plant growth will be less. Lastly, if the pH is altered then the rate of photosynthesis will also alter. If the optimum pH is not met, then the plant will obtain sufficient food or nutrients, thus the plant will not grow sufficiently. Therefore the experiment was successful in supporting the research and hypotheses.