Conditions Necessary for Germination
Group Members:
Jamyang Dorji (BE091912)
Ugyen Dorji (BE091921)
Ugyen Thinley (BE091922)
Samtse College of Education
BIO- 1302
Mr. Ranisngh Tamang
23rd October 2009
Aims and Objectives of the Project
At the end of the project, each member of the group should be able to:
1. Prove water is necessary for germination.
2. Prove the suitable/ optimum temperature is necessary for germination.
3. Prove air (O2 ) is also necessary for germination.
4. Set- up all the experimental apparatus to prove the necessary conditions.
5. Write down the steps involve in the procedure.
Achievement:
At the end of our project, we could achieve and prove that :
1. The water is necessary for germination.
2. The suitable/optimum temperature is necessary for germination.
3. Air/moisture – Oxygen is necessary for germination.
Failure/Problem
When we carryout the experiment and in set-ups we encountered lots of difficulties and obstacles. The following points include the difficulties and obstacles as follows:
At the very inception of setting those set-ups, we struggled to collect materials required for the experiment. In order to set up the apparatus for experiment we need materials like different types of seeds and pyrogallic acids. We struggled even to get aforementioned materials as we are new to the localities and the places as well. Therefore, we had to go to one of the bars to get seeds and we could get the required seeds for the experimental set-ups.
We faced problem in getting the bean seeds which is actually the best and suitable seed to prove the necessary conditions for germination. But in our first experimental set up we failed to get the bean seeds yet we carried out our experiment with maize seeds which we could successfully prove the necessary conditions, but we failed some aspects like experiment in proving the oxygen is necessary for germination.
We failed to prove the experimental set up to prove the oxygen is necessary as we used the pyrogallic acid as we used it in solid form. But after we browsing the internet and with the help from module tutor we came to know that pyrogallic acid function well when it is dissolved in water. After using this we could found out that oxygen was observed by the pyrogallic acid only in dissolved/ liquid form.
One of our problems is due to failure in proper sealing of corks. This leads to entrance of oxygen from surrounding. If we had properly sealed the corks with grease then our experiment would have successfully completed on our first attempt.
Hypothesis
Water - is required for germination. Mature seeds are often extremely dry and need to take in significant amounts of water, relative to the dry weight of the seed, before cellular metabolism and growth can resume. Most seeds need enough water to moisten the seeds but not enough to soak them. The uptake of water by seeds is called imbibitions, which leads to the swelling and the breaking of the seed coat. When seeds are formed, most plants store a food reserve with the seed, such as starch, proteins, or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated that break down these stored food resources in to metabolically useful chemicals, providing energy and nutrients that the cells of the embryo need to divide and grow.
Oxygen - is required by the germinating seed for metabolism. If a seed is in soil with too much water or is buried too deeply, it can be cut off from the necessary oxygen. Oxygen is used in aerobic respiration, the main source of the seedling's energy until it grows leaves. Some seeds have impermeable seed coats that prevent oxygen from entering the seed, causing a type of physical dormancy which is broken when the seed coat is worn away enough to allow gas exchange and water uptake from the environment.
Temperature affects cellular metabolic and growth rates. Often seeds have a set of temperature ranges where they will germinate and will not do so above or below this range.Many seeds germinate at temperatures slightly higher than room-temperature 60-75F (16 - 24C), while others germinate just above freezing and others germinate only in response to alternation in temperature between warm and cool. Some seeds germinate when the soil is cool 28-40F (-2 - 4C), and some when the soil is warm 76-90F (24 - 32C). Some seeds require exposure to cold temperature (vernalization) to break dormancy. Seeds in a dormant state, it will not germinate even if conditions are favorable. In general the optimum temperature for the seeds to germinate is 25-300C.
Supporters
According to Vishnoi, H.S. (2000): (ICSE Concise Biology- Part I for Class IX)
Seed contains dormant embryo. In a dry seed the embryo is inactive. This stage is said to be dormancy- a period of rest. Externally, the seed appears to be without life, but in reality all the chemical activities are very slow and little foot is utilized. The seeds consumed oxygen and give out carbon dioxide, both in small quantity, and release heat as well. When place under proper conditions the dormant seeds awaken, i.e. it becomes active and starts growing into a seedling. Due to all these conditions lead to the formation of a seedling known as Germination. It also can be defined as the process of awakening and growth of the dormant embryo present inside the seed into seedling or young plant capable of independent existence under suitable conditions.
A fresh seed from a plant normally does not germinate even if the conditions for germination are favorable. It must pass through a period of dormancy during which it undergoes physiological maturation. (P.100- 102).
Savage, F. and Metzger,L.( 2006). Proved in the laboratory that the basic requirement for germination are water, oxygen and an appropriate temperature where the seeds are also found to be sensitive to light and/or nitrate. Germination commences with the uptake of water by imbibitions of the dry seed, followed by embryo expansion. This usually culminates in rupture of the covering layers and emergence of the radical, generally considered as the completion of germination.
(Retrieved 17th October 2009 from http://www.seedbiology.de/germination.asp)
According to Rastogi, V.B. (2003). (ISC Biology- Book II for Class XII) says:
Moisture/Water for germination brings about the activation of it dormancy. It is necessary for respiration as oxygen reaches the ptotoplasm only in the state of solution in water.
Uptake of oxygen and water softens the seed coat and the testa. Seeds swell up and embryo breaks through seed coat and comes out easily.
Oxygen. After germination growth of the seeds resume and rate of metabolism increases and seeds respires vigorously. Hence O2 is required in large quantities.
Temperature: A suitable temperature is also necessary for germination. Optimum temperature required is 25- 300C. Most seeds fail to germinate below 50C and above 45-500C above optimum temperature. (p. 215-216)
According to Das, K. S. and Mookerji, J. B (1973). (Outlines of Biology). Says when certain external conditions are satisfied, the dormant embryo begins to grow. Supply of water, favorable temperature, and adequate supply of oxygen are main external conditions essential for germination. Light also influenced on germination of some seeds but in most cases it retards germination at the early stages.
Water/moisture. The supply of water is very important for germination. The seeds absorb water and swells up. So seed coat softened and ruptures easily to make way for radical and plumule to come out.
Temperature. An optimum rate of temperature is also essential for germination. Seeds cannot carry on vital activities at very low or high temperature. Optimum temperature required is 25 – 350C.
Oxygen supply. The dry seeds respire very feebly. With the beginning of germination the rate respiration increases. So a constant supply of oxygen is essential. (p.16)
Conditions necessary for germination- Experimental Setups.
1. Water
2. Optimum/ Suitable Temperature
3. Air ( Oxygen)
1. Water( H2O)
In order to prove water is necessary for germination, the following setups were done:
We took two beakers and marked them A and B. In beaker A, we placed some seeds of maize on wet cotton which is the water medium. In beaker B, we placed similar seeds but on dry cotton without water medium. We kept both beakers in ordinary conditions and did observation atleast for three weeks.
Observation Table
Days / Beaker A / Beaker B1st / No germination and growth / No germination and growth
2nd / There was growth of radical and plumule which the growth of radical was found to be prominent. / There was no growth of radical and plumule.
3rd / The actual germination started with growth of plumule and radical prominently / No growth and germination
4th / The plumule developed into shoot and was found above the surface of the ground. / No growth and germination
5th / With the development of shoot, the growth of leaves has also taken place. / No growth and germination
6th / We observed the growth of leaves was very prominent. / No growth and germination
7th / Those leaves developed here seemed to be welting and drying. To ensure it intact we poured water and continued observation for next two weeks. / No growth and germination
2nd Weeks / There was well growth and development of shoots and leaves as we ensured the availability of water supply. / No growth and germination
Mid- 2nd weeks / We could observe that the development and growth of shoots and leaves were of less compare to the former stage. / No growth and germination
3rd weeks / The growth and development was of
bit less prominent due to the fact that besides continuous supply of water the medium lacks the nutrients and minerals. / No growth and germination
Mid-3rd weeks / Though there was no prominent welting and drying of shoots and leaves yet the growth and development was no visible at all. There was also slight welting of leaves. / No growth and germination
Inference
In a day or two, seeds in beaker A (with wet cotton) were found to be germinated but not in B as shown in observation table. The germination in beaker A indicates that water is necessary for germinations.
Comparative studies
Again we set up an experiment in two beakers A and C. Beaker A with wet cotton ( Water medium) and Beaker C with soil( Water and mineral s medium) to observe in which condition the germination take place faster and efficiently. The comparative studies are as in the given observation table.
Observation Table
Days / Beaker A / Beaker C1st / No germination and growth / Germination of radicle
2nd / There was growth of radical and plumule which the growth of radical was found to be prominent. / There was growth of radical and plumule in which in which the growth of radical and plumule was too prominent. We also observed the length of shoots and leaves was more than in the latter beaker A
3rd / The actual germination started with growth of plumule and radical prominently / The germination and growth shoots were of faster and longer in length. Both the radical and plumule are grown prominently. Plumule in this stage already grows into shoots.
4th / The plumule developed into shoot and was found above the surface of the ground. / There was growth of leaves from the shoots.
5th / With the development of shoot, the growth of leaves has also taken place. / The leaves and the shoots development were very prominent and grown faster than the beaker A.
6th / We observed the growth of leaves was very prominent. / The leaves and the shoots development were very prominent and grown faster than the beaker A compare to the earlier stage.
7th / Those leaves developed here seemed to be welting and drying. To ensure it intact we poured water and continued observation for next two weeks. / Those leaves developed here didn’t seem to be welting and drying but to the very less extend. Even so we poured a 50ml water daily to ensure continuous supply and continued the observation for next two weeks.
2nd Weeks / There was well growth and development of shoots and leaves as we ensured the availability of water supply. / The growth and development of shoots and leaves were found growing as same as in the former beaker A.
Mid- 2nd weeks / We could observe that the development and growth of shoots and leaves were of less compare to the former stage. / The development and growth of shoots were of not very prominent and same that of the former beaker A
3rd weeks / The growth and development was of
bit less prominent due to the fact that besides continuous supply of water the medium lacks the nutrients and minerals. / The growth and development was of bit less prominent due to the fact that besides continuous supply of water the medium the nutrients and minerals contents in the soil has been utilized in the growth and germination.
Mid-3rd weeks / Though there was no prominent welting and drying of shoots and leaves yet the growth and development was not very visible at all. There was also slight welting of leaves. / Though there was no prominent welting and drying of shoots and leaves yet the growth and development was not very visible at all. There was also slight welting of leaves. The prolongingness of the plant was of more than the former Set up.
Inference