Biology Extended Essay

Sukanya Vartak002149 (076)

Biology Extended Essay

[To investigate the growth enhancing effect of Aloe vera gel on germinating seeds]

Abstract

gel affect their rate of germination?

My essay aims to investigate the growth enhancing effect of Aloe vera gel on germinating seeds. The idea of carrying out this investigation came to me after going through a research paper in which the effect of cactus extracts on seed germination were studied. Since I could not find any previously done research on the growth enhancing effect of Aloe vera gel, all the data collected and the investigation is first hand. In my investigation I used 5 different species of seeds; each seed was taken in two batches. One of the batches was treated with Aloe vera gel and the other batch was used as a control to observe any distinction in the type of growth. These seeds were then left to germinate and observed for a period of 6 days. The observations showed that the seeds treated with Aloe vera gel showed rigor in growth and hence to explain this growth enhancing effect of the gel it is further put to test for various parameters moisture content, carbohydrates, proteins, nitrates). The results of the analysis justified the observation that I obtained in the latter part of the experiment. Therefore based on the results I concluded that treatment with Aloe vera gel caused most of the seeds the seeds to germinate faster either because of the great moisture retaining ability or because it helps the seeds to overcome dormancy. The growth enhancing effect of the gel can be beneficial to the agricultural industries since they can coat the seed with the gel before selling them, this will cause the seeds not only to germinate faster but also decrease the wastage of seeds incapable of early germination.

Introduction

"Germination is the growth of anembryonicplant contained within a seed"[1], in simple words germination is the process in which a seedling starts to grow from its state of dormancy. In its state of dormancy there are no metabolic activities taking place in the cell. When the cell is finally exposed to favorable conditions the metabolic processes resume and it germinates. For a seed to germinate some factors that need to be favorable include:

a) Water: seeds are generally dry and therefore need plenty of water to initiate the metabolic processed in the seed. Seeds need this water to moisten and to swell up and break the seed coat to grow into plants. The seeds also use water to activate the hydraulic enzymes. These enzymes then go on to breakdown the reserved food into useful chemical energy.

b) Oxygen: oxygen helps the leaf to respire since the leaf requires some energy before it finally starts photosynthesizing. The seed initially gets this oxygen from the pores in the soil where air is trapped.

c) Temperature: temperature is the main factor affecting the activation process. This is because temperature plays a key role in the activity of enzymes. Enzymes are temperature specific and therefore under extremely low conditions they are deactivated and under extremely high temperatures they denature due to alteration in their active sites[2]. Therefore the seed needs an optimum temperature to start germinating.

However, many seeds do not germinate, because they are killed by external factors such as unfavorable environmental conditions, animals or pathogens or they are quiescent[3]. Sometimes failure to germinate is termed as dormancy. Dormancy does not have a specific definition but is the measured by the absence of germination, a condition in which a seed is not allowed to germinate. This condition is controlled by many factors, water, temperature, gases, hormones, enzymes, etc. these conditions block germination not letting the seeds to grow. This is what causes the seeds to survive harsh conditions until finally under favorable conditions they germinate. Dormancy is incorrectly associated with the absence of germination, whereas it defines the factors that are actually necessary for germination. The factors that are favorable for germination are indeed the factors that terminate seed dormancy and induce germination. There are many types of seed dormancies:[4]

1) Psychological dormancy: is the most abundant form, found in most gymnosperms and all major angiosperms. There are three levels to this kind of dormancy deep, intermediate and non-deep. In deep dormancy they either don't grow or produce abnormal seedlings, in intermediate dormancy the seeds produce normal seedlings. GA treatment can break dormancy in some of these seedlings, and the non-deep dormant seeds produce normal seeds and dormancy can easily be broken by treatment with GA.

2) Morphological dormancy: in this type of dormancy the embryos of the seed is differentiated but not developed. These types of seeds are not physically dominant but since they are undeveloped they require a lot of time to grow.

3) Morph psychological dormancy: these seeds are not only undeveloped but also have a psychological component to their dormancy and therefore they need a dormancy breaking treatment.

4) Physical Dormancy: this kind of dormancy is because of the presence 2 or more layers of palisade cells on the seed coat. This condition is commonly referred to as hardness. These layers keep the seed impermeable until they are exposed to some factors that make the seed permeable. Most often these factors include high temperature, fire, drying, or sometimes even passage through the digestive tracts of some animals.

5) Combinational Dormancy: This is a combination of psychological as well as physical dormancy.

Seed dormancy can also be otherwise be broadly classified into coat imposed dormancy and embryonic dormancy. Coat imposed dormancy is imposed on the embryo of the plant by the seed coats and other surrounding tissues. The embryos of these kinds of seeds only germinate when either the seed coat is removed or damaged. There are many mechanisms of Coat imposed dormancy:[5]

1) Impermeability to water: this is the most common cause of seed dormancy where the seed coat is impermeable and hence does not permit intake of water.

2) Mechanical constrain: in some cases the seed coat is physically too rigid and therefore does not allow the radical to penetrate through it. This is common among seeds with lignified seed coats and can also be seen in non lignified seeds where the seed coat can suppress growth of embryo. For the seeds to germinate the cell wall must be weakened using cell wall degrading enzymes.

3) Interference with gas exchange: some coats are even impermeable to oxygen and due to no oxygen supply the seed does not germinate.

4) Retention of inhibitors: intact seed coat does not allow the inhibitors, like abscisic acid, cytokinines, ethylene etc. to leave the seed like in normal seeds.

The second type is the embryo dormancy which is not necessarily due to exertion by the seed coat but is inherent in the embryo. This kind of dormancy can be relieved by amputation of cotyledons. Embryo dormancy is caused due to the presence of inhibitors and absence of growth promoting substances like GA (gibberellic acid).[6]

The releasing from seed dormancy is also controlled by several external factors and methods:

1) After ripening: this is a method in which the seed is dried to an extent. The seed cannot be dried too much since this would diminish the effect of the after ripening.

2) Vernalization: low temperature is another factor that can release dormancy. Some seeds require a period of cold before they finally germinate. This is probably why seeds germinate in the spring after the winter and not the fall.

3) Light: some seeds may require a little exposure to light pre germination. Surprisingly all light requiring seeds have seed coat dormancy and the removal of the seed coat allows the seed to germinate in the absence of light.

4) Growth enhancing substances: growth enhancing substances include plant hormones such as gibberellins and auxins. Literature also shows the use of various types of gels as a medium of plant growth, clay type gels, natural gels and synthetic organic gels to name some. These gels provide the required water to the seeds for germination. Some Japanese studies also show that these gels do not merely provide water but also other substances that the plant requires for growth like hormones and fertilizers. Coating the seeds not only improves the water retaining ability but also provides a suitable surface for excellent air permeability.

In my investigation I have used the same principle of gel coating using Aloe vera gel extraction to investigate it effect on the percentage of germination of seeds.

Aloe vera (binomial name: Aloe vera), also commonly called the medicine aloe finds its origin in the Canary Islands and Cape Verde of North Africa. Aloe vera is commonly found and grown in an arid climate. It is a stem less short plant that grows about 60 - 100cm tall with fleshy and thorny leaves. This species has many synonymous species, for example Chinese aloe, true aloe, first aid plant, Indian aloe, etc. Aloe vera is said to be a medicinal plant and also has a number of uses.

Aloe vera has several medicinal properties and scientists have also discovered 150 nutrients present in the Aloe vera some of which are: enzymes, amino acids, vitamins, minerals etc. Some of the important constituents are glycosides, aloins, barbaloin. When Aloe vera is cut, it gives out two fluids, the one on its skin is an irritant where as the latter that is released whenever the flesh is cut is said to have healing properties. Although there is no strong evidence of any cosmetic or therapeutic effectiveness of Aloe vera, it still continues to be the ingredient in a lot of things from lotions to desserts. There are over 500 uses of Aloe vera some of which include treatment of cuts, scars due to its antiseptic and anti fungal, antiseptic made from aloe are used to kill moulds, fungus, viruses, bacteria, etc. it is also popularly used as a moisturizer since it tends to retain moisture. Its property to retain moisture makes is ideal to use in my experiment since I am investigating the effect of gels on the rate of germination.

gel affect their rate of germination?

Methodology

The complete investigation is carried out in two parts.

Part 1: Two sets of each type of seeds were taken. One group was coated with Aloe vera; the second was germinated under regular conditions. Each of the groups were then left to germinate and will be observed for a week. Then the percentage germination of the seeds was calculated daily for a period of seven days. At the end of which a comparative graph was made to compare the rate of germination in each case.

Part 2: This part of the experiment dealt with the Quantitative and qualitative analysis of the Aloe vera gel and the nutrients that were present in the gel. I carried out tests for calculating the amount of Carbohydrate by the Anthrone reagent method, proteins by Folin-Lowry method, percentage of water by dry mass determination, phosphates, nitrates and sulfates were qualitatively determined.

Compiling part 1 and Part 2 of the experiment, Part 1 served as the main experiment whereas, Part 2 helped in providing substantial explanation to the results obtained in part 1.

The investigation was carried out on the following dicotyledonous seeds:

1) Mung bean (Vigna radiata)

2) Pea (Pisum sativum)

3) Moat bean (Vigna aconitifolia)

4) Chick pea (Cicer arietinum)

5) Kidney beans (Phaseolus vulgaris)

Part 1: Germination

The part 1 of the experiment was to study the effect of Aloe vera coating on the % germination of seeds.

Requirement                                   Quantity
Petri dish                                    10
Cotton                                        1 roll
Water Spray bottle                            1
Aloe vera gel (freshly extracted)             100 ml
Peas                                          50 seeds
kidney beans                                  50 seeds
Mung beans                                    50 seeds
moat beans                                    50 seeds
chick peas                                    50 seeds

Procedure

I took 25 seeds of each type and soaked them in the Aloe vera gel for 5 minutes such that a layer of the gel applied evenly over the seed. Then I left them to dry overnight so that the layer formed a coat of Aloe vera. In the lab I took 10 and made a base of cotton on each of them. Then I sprayed the cotton with water to moisten the cotton to provide an ideal surface for germination. I took 5 dishes and placed the seeds that were treated earlier in them labeled the dishes as "Treated". Then the seeds that were not treated were also placed the other 5 dishes and labeled "Control". These seeds were then kept in a dark cupboard for germinating. The following data collection tables give the observation made during the experiment.

Flaws in the Experiment

1) The extracted Aloe vera gel was kept in the freezer; this could have altered some of its properties.

2) The sample size of the seeds was small therefore my answer was based on assumptions to an extent.

Part 2

Chemical analysis of Aloe vera

In this part I tied to quantitatively analyze the elemental constituents of aloe vera.

Experiment 1: Estimation of the water to dry mass ratio in 10g of Aloe vera.

Procedure

I took 10g of Aloe vera Pulp sample and placed it on a Petri plate. Then I weighed the mass of the Petri plate and the sample together and made a note of it. Then to evaporate all the water and to obtain the dry mass of the sample I placed the Petri plate in the incubator and increased the temperature to around 80-100 degree Celsius. After all the water had dried out I assumed the loss of mass as the mass of water lost and subtracted it from the initial mass of the sample to obtain the dry mass of Aloe vera.

Results: The amount of water as per my experiment per given mass of Aloe vera gel sample is 91.6% (0.03%)[7]

Experiment 2: Estimation of protein content by Lowry's method[8]

REAGENTS

A. 2% Na2CO3 in 0.1 N NaOH
B. 1% NaK Tartrate in H2O
C. 0.5% CuSO4.5 H2O in H2O
D. 48 ml of A, 1 ml of B, 1 ml C
E. Phenol Reagent - 1 part Folin-Phenol [2 N] : 1 part water

[Reagents A, B and C may be stored indefinitely]

BSA Standard - 1 mg/ ml

Bovine Serum Albumin: 5 mg in 5 ml of water [1 g / l].
Freeze 1 ml aliquots.

PROCEDURE

1. Set up eleven sets of three 16 x 150 mm test tubes in rack.
2. Add Bovine Serum Albumin [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 l] to these tubes.
3. Add 2 ml of solution D to each test tube.
4. Incubate for 10 minutes at room temperature.
5. Add 0.2 ml of dilute Folin-phenol solution to each tube.
6. Vortex each tube immediately.
9. Incubate at room temperature for 30 minutes.
10. Determine absorbance of each sample at 600 nm.
11. Plot absorbancevs.mg protein to obtain standard curve.
12. Set up triplicate assays for all "unknowns".

Flaws in the procedure

While performing this experiment for the first time it was impossible to obtain the optical density value since the protein content in the sample was extremely high. Hence I had to dilute the sample (1ml of the gel in 100ml water) therefore I find the results obtained by this way unsatisfactory and hence I used the Kjeldhal method.

Experiment 3: estimation of the amount of carbohydrate (sugars) present using the Anthrone Reagent method[9]

PRINCIPLE

Carbohydrates are first hydrolyzed into simple sugars using dilute hydrochloric acid. In hot Acidic medium glucose is dehydrated to hydroxymethyl furfural. This compound forms with Anthrone a green colored product with an absorption maximum at 630 nm.

REAGENTS

2.5 N HCl

Anthrone reagent: Dissolve 200 mg Anthrone in 100 ml of ice-cold 95% H2SO4. Prepare fresh before use.

Standard glucose: StockDissolve 100 mg in 100 ml water. Working standard10 ml of stock diluted to 100 ml with distilled water. Store refrigerated after adding a few drops of toluene.

PROCEDURE

1. Weigh 100 mg of the sample into a boiling tube.

2. Hydrolyze by keeping it in a boiling water bath for three hours with 5 ml of

2. 5N HCl and cool to room temperature.

3. Neutralize it with solid sodium carbonate until the effervescence ceases.

4. Make up the volume to 100 ml and centrifuge.

5. Collect the supernatant and take 0.5 and 1 ml aliquots for analysis.

6. Prepare the standards by taking 0, 0.2, 0.4, 0.6, 0.8 and 1 m of the working standard.

'0' serves as blank.

7. Make up the volume to 1 ml in all the tubes including the sample tubes by adding distilled water.

8. Then add 4 ml of Anthrone reagent.

9. Heat for eight minutes in a boiling water bath.

10. Cool rapidly and read the green to dark green color at 630 nm.

11. Draw a standard graph by plotting concentration of the standard on the X-axis versus absorbance on the Y-axis.

12. From the graph calculate the amount of carbohydrate present in the sample tube.

Experiment 4: Estimation of nitrogen using Kjeldahl method[10]

Principle

The nitrogen in Protein or any other organic material is converted to ammonium sulphate when digested with sulphuric acid. On steam distillation this salt liberates ammonia which is collected in boric acid solution and titrated against standard acid. 1ml of 0.1N acid is equivalent to 1.401mg N; using these values the nitrogen content in the sample is calculated.

Requirement

Kjeldahl flasks: 30ml hard glass Flask

Digestion Rack: Commercial heating apparatus

Sulphuric acid: Concentrated (97-99%)

Mercuric oxide

Potassium sulphate

Sodium hydroxide: Dissolve 600g of NaOH and 50g Na2S2O3.5H2O in distilled water to make 1liter.

Indicator Solution: methyl red (0.2g/100ml ethanol), methylene blue 0.2g/100ml ethanol). For a mixed indicator 2 parts of methyl red solution are added to one part of methylene blue.

Boric acid 4% solution

Standard HCl or H2SO4 0.02N

Boiling Chips or Glass beads

Procedure

Digestion

Distillation

1) Weigh approximately 1 g ground sample into digestion flask, recording weight (W) to nearest 0.1 mg. Include reagent blank and high purity lysine HCl as check of correctness of digestion parameters. Weigh a second subsample for laboratory dry matter determination.

2) Add 15 g potassium sulfate, 0.04 g anhydrous copper sulfate, 0.5 to 1.0 g alundum granules, or add 16.7 g K2SO4, 0.01 g anhydrous copper sulfate, 0.6 g TiO2 and 0.3 g pumice. Then add 20 mL sulfuric acid. (Add additional 1.0 mL sulfuric acid for each 0.1 g fat or 0.2 g other organic matter if sample weight is greater than 1 g.)

3) Place flask on preheated burner (adjusted to bring 250 mL water at 25oC to rolling boil in 5 min).

4) Heat until white fumes clear bulb of flask, swirl gently, and continue heating for 90 min for copper catalyst or 40 min for CuSO4/TiO2 mixed catalyst.

5) Cool, cautiously add 250 mL distilled water and cool to room temperature (less than 25oC). Note: If bumping occurs during distillation, volume of water may be increased to ca. 275 mL.

1. Prepare titration flask by adding appropriate volume (VHCl) accurately measured acid standard solution to amount of water so that condenser tip is immersed (try 15mL acid and 70mL water if undecided). For reagent blank, pipette 1mL of acid and add approximately 85mL water. Add 3 to 4 drops methyl red indicator solution.

2. Add 2 to 3 drops of tributyl citrate or other antifoam agent to digestion flask to reduce foaming.

3. Add another 0.5 to 1.0 g alundum granules

4. Slowly down side of flask, add sufficient 45% sodium hydroxide solution (approximately 80mL) to make mixture strongly alkali. (Do not mix until after flask is connected to distillation apparatus or ammonia will be lost.)

5. Immediately connect flask to distillation apparatus and distil at about 7.5 boil rate (temperature set to bring 250mL water at 25oC to boil in 7.5 min) until at least 150mL distillate is collected in titrating flask.

6. Remove digestion flask and titrating flask from unit, rinsing the condenser tube with distilled water as the flask is being removed.

Titration

1. Titrate excess acid with standard sodium hydroxide solution to orange endpoint (colour change from red to orange to yellow) and record volume to nearest 0.01mL (VNaOH). Titrate the reagent blank (B) similarly.

Data Collection

Part 1

Day 1:

The seeds were left for germination.

Day 2

Sr. num        Seed           Number of seeds Germinated         % germination            
                              Coated          Non-Coated         Coated       Non-Coated
1              Mung           6               4                  24.00        16.67
2              Pea            1               -                   4.00         0.00
3              Chick Pea      3               1                  12.00         4.17
4              kidney Beans   -               -                   0.00         0.00
5              Moat beans     5               4                  20.00        16.67
             

From the results displayed above it can be observed that the seeds that were treated with Aloe vera showed a hasty growth as compared to the ones that were not treated. This effect is not seen in all cases since the kidney beans did not show any sign of growth. However we cannot conclude immediately that the haste in the growth of the seeds was due to the treatment with Aloe vera.

Day 3

Sr. num        Seed           Number of seeds Germinated         % germination
                              Coated          Non-Coated         Coated       Non-Coated
1              Mung           9               10                 36.00        40.00
2              Pea            5               3                  20.00        12.00
3              Chick Pea      7               3                  28.00        12.00
4              kidney Beans   -               -                   0.00         0.00
5              Moat beans     13              6                  52.00        24.00
             

The seeds that were treated yet again showed similar results except for Mung beans and Kidney beans. The control of the Mung bean showed a greater increase in the number of seeds of the control that germinated. The kidney beans did not show any sign of growth yet.

Day 4

Sr. num        Seed           Number of seeds Germinated         % germination
                              Coated          Non-Coated         Coated       Non-Coated
1              Mung           17              13                 68.00        52.00
2              Pea            13              6                  52.00        24.00
3              Chick Pea      15              7                  60.00        28.00
4              kidney Beans   -               2                   0.00         8.00
5              Moat beans     19              12                 76.00        48.00
            

The seeds still showed the same response, more treated seeds germinated. In case of the Mung beans the treated beans showed an increase in percentage germination. Two kidney beans from the control sample grew. There was a powdery substance that looked like fungus was found to grow on the Kidney bean seeds of the treated sample and they did not show any sign of growth.

Day 5

Sr. num        Seed           Number of seeds Germinated         % germination
                              Coated          Non-Coated         Coated       Non-Coated
1              Mung           22              18                 88.00        72.00
2              Pea            19              15                 76.00        60.00
3              Chick Pea      20              12                 80.00        48.00
4              kidney Beans   -               3                   0.00        12.00
5              Moat beans     23              16                 92.00        64.00
            

The seeds still show the same observations. The greatest variation in the percentage germination can be seen in the chick peas sample the control showed 32% less growth than the treated sample of chick peas. The percentage germination of chick peas has increased from 8% to 12% however in the treated sample the fungus like substance spread completely and therefore to avoid any further spreading of the substance to other seeds I removed the sample.

Day 6

Sr. num        Seed           Number of seeds Germinated         % germination
                              Coated          Non-Coated         Coated       Non-Coated
1              Mung           All             23                 100.00       92.00
2              Pea            24              22                  96.00       88.00
3              Chick Pea      All             18                 100.00       72.00
4              kidney Beans   Removed         Removed              0.00        0.00
5              Moat beans     All             19                 100.00       76.00
             

Observations: The powdery layer covered all the seeds therefore to avoid infecting the other plants in the experiment I removed that sample.

All the seeds in most of the sample have already germinated and in all cases the treated seeds showed hasty germination. Since most of the samples had all germinated I stopped sampling on this day. According to the observations made so far the seeds that were treated germinated faster than those that were not, except in the case of the kidney beans where the beans reacted negatively to the treatment with Aloe vera.

Part 2: Experiment 2

Volume / cm3           % absorption
0.2                    0.11
0.4                    0.14
0.6                    0.22
0.8                    0.25
1.0                    0.34
Sample                 0.11
            

From the standard graph we know that the amount of Protein per 1ml of sample is estimated to be 0.23ml in 1ml of solution.

Part 2: Experiment 3

Volume ( 0.01 cm3)       Optical Density ( 0.01)
0.2                       0.182
0.4                       0.303
0.6                       0.546
0.8                       0.636 
1.0                       0.949
1ml sample  50 dilution  0.49
            

From the graph the concentration of the sample of optical density 0.49 is estimated to be 2.85mg/ml.[11]

Part 2: Experiment 4

Titration Values

Sample against standard acid = 14.4ml 0.05ml

Blank = 0.9ml 0.05ml

From the experiment the amount of nitrogen g/kg was obtained to be 3.53g/kg 6%

And the protein content estimated by this method was 22.06 g/kg or 0.022 mg/g[12]

Results and Discussion

Part 1

Observations from the germinating samples showed that in all cases (except for Kidney beans) the seeds treated with Aloe vera gel germinated faster than the seeds that were not treated. This means that the gel had some growth enhancing effect or some excitatory action that contributed to the early initiation of germination in the treated sample.

However we cannot be so sure about the enhancing effect of the gel. According to the result Part 2 experiment 2 the gel contains approximately 91% of water in it! This means that the treatment with the gel may have only provided the seeds with the required moisture. The addition of water contributes to breaking of seed dormancy of several kinds of seeds[13]. But, if the seeds had coat imposed dormancy we can also say that treatment with Aloe vera may have improved seed permeability.

The use of Aloe vera in creams such as moisturizers for burns and scars is said to be due to its property to retain moisture and also promote cell growth. These properties however are not certain but its use as an antiseptic has also been accounted for in history and therefore brings about a new argument in my investigation. It is possible that Aloe vera could promote faster germination by promoting cell growth and giving the cell an ability to retain moisture for a longer time.

According to the observations all the treated seeds germinated whereas the seeds that were not treated did not show complete germination. This again could mean that the treated seeds were exposed to some sort of substance that promoted germination by breaking dormancies. When a seed is left for germination, the first thing it does is imbibes water to swell up. This swelling causes the seed coat to become more permeable to oxygen and thus effective germination can happen. Sometimes the coat of the seed had coat imposed dormancy and is therefore it requires something to destroy or digest to impermeable seed coat in order to make it permeable. The seeds that were not treated were not in contact with anything except moisture therefore the dormancy was not broken effectively.

Part 2

Experiment 1: Estimation of the water to dry mass ratio in 10g of Aloe vera

The determined percentage of water was around 91% in any given mass of the plant this again suggests that the high water content of the plant could account for the hasty growth in the treated seeds. Water is needed to activate the hydraulic enzymes in the seeds that will then cause the seed to germinate. And since the seeds that were treated were exposed to more water earlier and the control were merely sprayed with water it is possible that that is why the seeds grew faster.

Experiment 2: Estimation of Protein content by Lowry's Method

Concentration of protein that I obtained per 1ml of the solution was 0.23 of sample; however the sample was initially diluted in 50ml before using it in the experiment. This had to be done since the sample had such high protein content that the colorimeter available in school lab did not have the necessary range for the correct reading. This suggests that the sample of Aloe vera has high protein content. Presence of protein also suggests that there are possibly many enzymes in the sample. This could mean that the seeds could use these enzymes and hence germinate faster. That is some of these enzymes could act like degrading enzymes to help the seed overcome coat imposed dormancy.

Experiment 3: estimation of the amount of carbohydrate (sugars) present using the Anthrone Reagent method

The amount of carbohydrate estimated by this method was found to be 2.85mg/ml. This is relatively very high content. Carbohydrates are energy giving molecules and hence when present in ample amounts provide energy to the seed during germination.

Experiment 4: Estimation of nitrogen using micro- Kjeldhal method

The high amount of nitrogen again shows the presence of protein which in turn leads to the same conclusion that there is a possibility that a lot of these proteins are enzymes out of which some can act like degrading enzymes that will help the seeds overcome any coat imposed dormancy.

Conclusion

Looking at the results and discussions of my investigation it can be concluded that all the results support the idea that the treatment with Aloe vera gel has got a growth enhancing effect on germinating seeds. The results showed a high water, protein and carbohydrate content. Literature shows that all of these factors are necessary for germination to happen and thus treatment with Aloe vera gel enhances growth the germination stage. Another aspect that I had discussed was that there is a possibility that the gel also helped the seeds overcome various dormancies due to the presence of a variety of enzymes and high water content. However we do see that this does not really apply to all types of seeds since my sample of Kidney beans seeds showed rotting because of the formation of a fungus like substance and near death symptoms.

The investigation can be used as a platform for further research in the field of agriculture. The growth enhancing effect of Aloe vera can be studies further on more varieties of the seeds and therefore get a clearer picture of the actual effect of the gel on most of the seeds. The gel can also be used to coat seeds before selling so that they are able to germinate faster or in some cases reduce the dormancy period of the seeds. Another use of Aloe vera gel can be to replace Sodium Alginate, a polymer, in the transportation of synthetic seeds. The tissue cultured derived somatic embryos, which are coated with sodium alginate for their storage or for their transportation can be coated with sterilized Aloe vera gel. When these seeds are coated with Sodium alginate, artificial growth medium needs to be added for the desired enhancing effect, here the advantage of adding Aloe vera gel is that the gel not only provides a natural coating but also has enhancing effects.

Appendix

Processing of Part 2

Experiment 1:

The mass of sample taken = 10.075g (0.001g)

Mass of the Petri plate with sample = 97.100g (0.001g)

Mass of the Petri plate with dry sample = 87.774g (0.001g)

Mass of water lost = Mass of Petri plate with sample - mass of Petri plate with dry sample

= (97.001 - 87.774) (0.002g)

= 9.227g (0.001g)

So, the Dry mass = Mass of sample Taken - Mass of water lost

= (10.075 - 9.227) (0.003g)

= 0.848g (0.003g)

Therefore we can use this to calculate the %mass of water in Aloe vera.

% of water per mass of Aloe vera = mass of water mass of sample taken 100

= 9.22710.075 100

= 91.6%

Error Calculation

?mass of samplemass of sample+?mass of water mass of water 100

= 0.00110.075+ 0.0029.227100

= 0.03%

Therefore the % mass of water in a given sample of Aloe vera is estimated to be

= 91.6% (0.03%)

Experiment 3:

In the procedure, in the preparation of the standard glucose solution we added 100mg of the sugar to 100ml of water. This made the concentration of the solution 1mg/ml. Then, 10ml of the prepared solution was taken and diluted to 100ml, now the solution has 10mg of sample in 100ml. now the concentration is 0.10mg/ml.

From the graph, the corresponding concentration for the Optical Density of the sample was found to be 0.57.

I now assume that 0.57ml of the stock solution was taken, therefore I calculated the mass of sugar in the sample using the following calculations:

0.57ml of the 0.1mg/ml solution was diluted to 1ml

So, in 1ml there is 0.1mg hence in 0.57ml there is = 0.57 0.11 = 0.057mg

However this solution was diluted since the actual carbohydrate content of the sample was very high. I had diluted 1mlof the sample to 50ml so, the actual mass of carbohydrates present in the sample is 50 times the calculated amount i.e. 50 0.057 = 2.85mg/ml of the gel.

Experiment 4:

N g/kg = ml HCl-ml Blanknormality 4.01weight (g)

= 14.4-0.90.02 14.011.078 =

Error Calculation

? ml HClml HCl+? ml Blankml Blank+ ? WeigntWeight

= 0.0514.4+0.050.9+0.0011.078100

= 5.996% or 6%

Therefore the amount of nitrogen g/kg = 3.53g/kg 6%

From this concentration we can now calculate the mg of protein by multiplying the amount of nitrogen content into 6.25.

= 6.25 3.53 = 22.06 g/kg or 0.022 mg/g

Bibliography

Jirage, R. (n.d.). Steps of Seed Germination. Buzzle Web Portal: Intelligent Life on the Web. Retrieved August 12, 2009, from http://www.buzzle.com/articles/steps-of-seed-germination.html

Post-dispersal embryo development, germination phenology, and seed dormancy in Cardiocrinum cordatum var. glehnii (Liliaceae s. str.), a perennial herb of the broadleaved deciduous forest in Japan -- Kondo et al. 93 (6): 849 -- American Journal of Botany. (n.d.). American Journal of Botany. Retrieved November 28, 2009, from http://www.amjbot.org/cgi/reprint/93/6/849

Leubner, G. (n.d.). The Seed Biology Place - Seed Dormancy. The Seed Biology Place - The Seed Biology Place. Retrieved November 23, 2009, from http://www.seedbiology.de/dormancy.asp#definition

germination: Definition from Answers.com. (n.d.). Answers.com: Wiki Q&A combined with free online dictionary, thesaurus, and encyclopedias. Retrieved November 20, 2009, from http://www.answers.com/topic/germination%20/

Subcuticular Secretion by Cactus Seeds Improves Germination by Means of Rapid Uptake and Distribution of Water -- BREGMAN and GRAVEN 80 (4): 525 -- Annals of Botany. (n.d.).Oxford Journals | Life Sciences | Annals of Botany. Retrieved November 19, 2009, from http://aob.oxfordjournals.org/cgi/reprint/80/4/525

Sadasivan, S., & Manickam, A. (2005).Biochemical Methods(Second Edition ed.). Coimbatore: New Age International (P) limited.


[1] http://www.answers.com/topic/germination Accessed on 20th November, 2009

[2] The active site of an enzyme is the site where it binds t its substrate during a reaction. Enzymes are substrate specific, and therefore any alteration in its active site will make the enzyme useless.

[3] Quiescent : state of dormancy during which even if external conditions are favorable seeds of certain plants do not germinate.

[4] http://www.seedbiology.de/dormancy.asp#definition , Accessed on 23rd November, 2009

[5] http://4e.plantphys.net/article.php?ch=t&id=8 accessed on 24th November, 2009.

[6] http://4e.plantphys.net/article.php?ch=t&id=8 accessed on 24th November, 2009.

[7] For Processing refer to Appendix on Page

[8] Sadasivan, S., & Manickam, A. (2005).Biochemical Methods(Second Edition ed.). Coimbatore: New Age International (P) limited.

[9] Sadasivan, S., & Manickam, A. (2005).Biochemical Methods(Second Edition ed.). Coimbatore: New Age International (P) limited.

[10] Sadasivan, S., & Manickam, A. (2005).Biochemical Methods(Second Edition ed.). Coimbatore: New Age International (P) limited.

[11] For Processing refer to Appendix on Page

[12] For Processing refer to Appendix on Page

[13] Leubner, G. (n.d.). The Seed Biology Place - Seed Dormancy. The Seed Biology Place - The Seed Biology Place. Retrieved November 23, 2009, from http://www.seedbiology.de/dormancy.asp#definition

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