Effect of salinity on growth of plant

Plants and germinating seeds both get their share of salt and other mineral from the water and the soil around them. Plants endure a set level of salinity to germinate which is what we will be finding out as which is the optimum level for them to germinate. Soil salinity cause severe problems in the agriculture sector worldwide. And different levels on salinity affect plants in different ways and hinder their growth in different ways.

Like the 2 major stress under salt conditions for plants are ionic and osmotic. On land salinity caused by drought are the most severe ones and in water the water bodies close to seawater face the highest salinity. Seedlings being the most  in respiration cause of water stress and reduction in photosynthesis. Level salinity around the globe can cause destruction of local ecosystems. As salinity can cause issues to young plants like imbalance in osmotic potential leading to poor water uptake, or by toxic ions on the embryo viability, which reduce shoot growth. As the salt effects cell division and enlargement in the growing point. Research conducted on which plant seeds land or water are more tolerable to salt is still fresh, though relative importance of osmotic and ionic effects on early halophyte growth is still incomplete as the seeds acquired are usually pre- germinated under non saline conditions.  Thus, its tuff to say wheatear halophytes are more tolerant to salty conditions as it totally depends on the species.

In our present study, I will use NaCl as experimental salt and the young seedlings after measuring the shoot length will be harvested keeping in mind ethical issues.

In my childhood days, I used to visit the garden near my house with my grandparents. This has become a habit which I tend to follow almost every time in their absence as well. As the Coronavirus hit the world, the daily routine of every human being got disrupted thereby forcing us to self-quarantine to meet the needs of the situation. After few months, when the restrictions were lifted to a certain level, I visited the nearby garden and realised that some plants died due to air sprays that were used to purify the surrounding air of any germ particles. It broke my heart when I realised that once a deep green leaf has turned into pale yellow. It made me think that whether the air purifying sprays  Which contained sodium hypochlorite affected the salinity of the soil or not. Now we all know that plants requires sodium which acts a micronutrient for its growth. So, the plants must grow to a considerable height but in this case they al dried up, developed a pale-yellow colouration and eventually died. Then it made me think that whether an increase in the percentage of soil salinity inhibits the growth of plant or not and therefore I decided to carry on with this investigation.

How does the growth of of moong beans (vigna radiata), measured in terms of maximum shoot height in cm depends on the percentage composition of the salt solution in which it is germinated and grown?

Sodium mainly acts a micronutrient in plant growth and also affects the cell division and hormonal discharge of the plant body. Traces of sodium are very much essential for the plant growth. Halophytes are plants that mainly prefer soil having high content of sodium chloride for their growth. Water also plays an important role in plant growth. It affects the turgidity of the plant and due to the turgor pressure and cell enlargement it affects the plant growth. All the important nutrients that are beneficial for the plant growth are mainly provided by the water intake by the plant. Dissolved sugar and other nutrients are transported by the water. plants require an optimum level of saline soil for the plant growth. Salinity affects the osmotic pressure around the root hair cells which indirectly affects the water uptake of the plant resulting which if not executed properly will lead to the dehydration of the plant. Thus, soil salinity plays a vital role in the growth of a plant.

Moong beans were chosen for this experiment as they are easily available and cost-effective. The seeds of moong beans do not require any particular temperature or atmospheric conditions for its growth. The growth happens naturally under toom conditions and makes the experiment feasible.

6 petri dishes were taken. 7 seeds of moong beans plant were taken in each petri dish. For the control observation, the petri dish was filled with tap water and for the other petri dishes, salt solution was used where the salt concentration varied from 1% to 5%. The seeds were allowed to germinate by keeping them under room temperature and near a source of light (preferably sunlight) and the vertical shoot height was measured using a thread for a period of 7 days.

In the article “Effects of salinity and sodicity on plant growth” published in the journal “Annual review of Phytopathology”, it was concluded that soil salinity affects the pH of the soil and therefore has a negative impact on the plant growth. The correlation constant was found to be -0.0124 further suggesting a negative impact of the soil salinity in the plant growth.

The maximum shoot height (in cm) does not depend on the percentage concentration of the salt solution in which it is grown. In case, any correlation is found that is because of experimental errors or random outcomes.

The maximum shoot height (in cm) does depends on the percentage concentration of the salt solution in which it is grown.

A) Preparation of NaCl salt solution (1% NaCl salt solution)

• 1.00 gm of sodium chloride crystals were taken by measuring it with a mass balance in a beaker.
• 100 gm of tap water was measured by a measuring cylinder and added to the beaker.
• The beaker was shaken and allowed to rest for some time.
• The same procedure was repeated for 2.00%, 3.00%, 4.00% and 5.00% NaCl solutions using 2.00 g, 3.00 g, 4.00 g and 5.00 g salt.

B) Preparation of the seeds for the experiment:

• 20 cc of the salt solution prepared was transferred to the petri dish by using a graduated pipette.
• 7 moong beans seeds were kept in the petri dish.
• The petri dish was kept near the window.
• After 24 hours the height of the germinating plant was measured using a thread and ruler.
• This process was continued for the next seven days.
• The same process was repeated in case of other concentrations of salt solution (2.00,3.00,4.00,5.00 % of NaCl solution).
• For control, (0.00% salt solution), tap water was used.

All ethical issues were kept in mind, and no solutions above 5% were taken to avoid serious damage to the plants. Solution was added to the cotton and not the soil to prevent contamination of the nearby plants.

• Safety gloves and safety masks were used.
• Any sort of edible items were not allowed inside the laboratory.
• The work-station was kept clean and organized.

Mean = \(\frac{(0.80+0.81+0.69+0.80+0.81+0.80+0.69)}{7}= 0.77\)

Standard deviation = \(\frac{(0.77-0.80)^2+(0.77-0.81)^2+(0.77-0.69)^2+(0.77-0.80)^2+(0.77-0.81)^2+(0.77-0.80)^2+(0.77-0.69)^2}{7} = 0.05\)