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Objective: Effect of pH on the growth and germination of radish seeds

Introduction:

As air pollution increased, acid rain & acid deposition are becoming significantly more common, which may effect plants and lead to lower the economy. We hypothesized that The lower the pH, the weaker the plants will be in terms of germination and plant height. If we lower the pH of the watering solution to acid rain, then plant growth will be delayed, or inhibited. Same thing if we add the radish seeds to a basic solution it will delay the growth of the plant, but wont inhabited it form growing.

Materials and methods:

For this experiment, five beakers were taken and each one of them was having different pH ranging from pH 5 to pH 9. Among these beakers, the beaker 1 and 2 contained acidic solutions i.e. pH 5 and pH 6; beaker 3 contained neutral solution i.e. pH 7; and beakers 4 and 5 contained basic solutions i.e. pH 8 and pH 9. All the beakers were labelled accordingly and their pH was confirmed with the help of pH paper. Further, paper towel was taken and cut down in the circle according to the size of petridish and fitted down inside the petridish. Similar procedure was done for 15 petridishes and 3 petridishes containing paper towel were placed inside each beaker. Furthermore, the radish seeds i.e. Raphanus sativus that were procured from Burpee Seed Co. were taken and 3 seeds were placed over the paper towel in the upper half of the petridish in each beaker. The arrangement was made in such manner that the seeds didn’t touch the solution kept in beaker. Afterwards, the beakers were covered with the plastic wraps and some holes were made in the cover for passage of air. The beakers were then placed next to the window facing the sunlight. The beakers were observed for the germination of seeds for 7 days and the length of seed sprouts were recorded on 7th day to analyze the effect of pH on the germination of seeds.

Results

Effect of pH on seed germination rate- The pH change will affect the germination and growth of the radish seeds and it was observed in the experiment. Initially, the seeds were in water sprouted and began to grow and allowed to grow in three dishes. The results of germination rate with different pH has been summarized in Figure 1 and 2. Figure 1 showed the results of seed germination with length of cotyledons in three seeds in a dish represents that increasing pH will decrease the growth of germination. The radish seeds in the acid base medium attempted to sprout but were unable to grow and died. The seeds in the alkaline base was not significant sprouted and began to grow and falls as time began and lead to die off. Day 1 data showed that at pH 5, the results observed was pink yellow and green has fur, shed shell with 1.33 cm length, while at pH 6 germination was slow in seeds with average 0.43cm. At pH 7, the results were leafs in one seed only while rest two showed pink, yellow and green, no shell, with leaves and one with no growth. Similarly, at pH8, results observed with germination with short leaves only, while at pH 9 start of leaves, pink, white, green, and other with green, little growth was observed.

Figure 1: Results of germination rate on day 1 at different pH

Similarly at day 02, similar pattern of results were observed but with increased growth of cotyledons. The results of day 2 with different pH are summarized in Figure 2. Similar pattern of growth has been observed with low growth at higher pH, while better growth at pH5, similar type of pattern as in Day 01.

Figure 2: Results of germination rate on day 02 at different pH

Overall, it can be concluded that pH tolerance for radish seeds, pH is the important factor, which was tested and proof at two different time point. It suggest that when the soil becomes alkaline with pH 9, the seeds were not able to grow.

Discussion

After carrying out the above seed germination experiment, it was found that the growth of radish seeds was significantly affected by change in water pH. The seeds treated with low pH i.e. acidic performed good germination rate with average length, green color cotyledons. The determination of the humidity along with pH in the original soil is needed to know the exact amount of seeds germination. We can conclude from our germination experiment that pH or change in pH is the reason that plants did not grow so well in presence of plenty water, and significantly less carbon. These factors, along with lack of ammonia, and nitrogen can also have contributed to slower growth in the radish seeds germination. Overall, the radishes seeds treated pH 5 showed significant growth in length out of the four type’s pH range. These lengths are comparable, though slightly less than the lengths with varied pH of the solution.

Conclusion:

Plants are crucial to our environment & human survival to provide us with oxygen & food.

We conclude form this experiment has proven that high acid solution such as acidic rain could inhibit plants from germination. Radish seeds grow best in natural pH 7.

Day 01

Dish 01 0.120185042515467 0.133333333333333 0.592546294487706 0.202758751009941 0.4371625682868 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 1.366666666666666 0.433333333333333 0.866666666666667 0.533333333333333 0.533333333333333 Dish 02 0.260341655863555 0.0666666666666665 0.533333333333333 0.45092497528229 0.0 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 1.333333333333333 0.366666666666667 0.533333333333333 0.7 0.0 Dish 03 0.290593262902712 0.0881917103688197 0.608276253029822 0.0 0.0 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 1.866666666666666 1.366666666666666 1.1 0.3 0.0

Length in cm

Day 02

Dish 01 0.0933333333333333 0.0881917103688207 0.433333333333333 0.0577350269189626 0.348393136812104 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 2.126666666666667 0.933333333333333 0.733333333333333 1.1 0.693333333333333 Dish 02 0.115470053837925 0.0666666666666665 0.533333333333333 0.45092497528229 0.0 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 2.5 0.366666666666667 0.533333333333333 0.7 0.0 Dish 03 0.144952099367726 0.251661147842357 0.69602043392737 0.0333333333333337 0.0 1.0 PH 5 PH 6 PH 7 PH 8 PH 9 2.863333333333334 2.1 1.633333333333333 0.466666666666667 0.0

Length in cm