Thursday, 18 July 2013

Literature Review

Literature Review

Generating Questions

What conditions does Hydrilla Plants require to stay alive and grow?
The growth habit of hydrilla enables it to compete effectively for sunlight. It can elongate very rapidly, up to one inch per day, until it nears the water surface. Hydrilla is able to grow under a wide range of water chemistry conditions. It is commonly found in oligotrophic (low nutrients) to eutrophic (high nutrients) lakes (Cook and L”nd 1982). It can grow in water up to about 7% the salinity of seawater (Haller et al. 1974) or higher (Steward and Van 1987); and it tolerates a wide range of pH, but tends to grow better at pH 7 (Steward 1991).
How to measure the growth of the Hydrilla Plant?
We will measure the height of the Hydrilla plants everyday using a tape or a ruler and we will record down how much the Hydrilla Plant has grown. At the same time, we would use a data logger to record the oxygen level of the plant, which will let us determine the growth state of the plant.

Why choose Hydrilla Plants instead of other aquatic plants?
Hydrilla plants are common and are found quite often, in freshwater lakes, ponds, rivers, impoundments and canals, they too have a highly specialized growth habit, physiological characteristics, and reproduction that make this plant well adapted to life in submersed freshwater environments.  It can grow quite quickly which allow us to complete the experiment in a relatively short amount of time, at the same time, the hydrilla is able to live at a shallow depth of a few inches or up to 20 feet.


Langeland, K. (9 July 2013) Hydrilla verticillata "The Perfect Aquatic Weed" retrieved from

Royle, L. (9 July 2013)  “Hydrilla verticillata” New York Invasive Species Information retrieved from

Types of Water

Carbonated Water
Carbonated Water is water into which carbon dioxide gas under pressure has been dissolved. The dissolved carbon dioxide gas under pressure might affect the growth of the Hydrilla Plants. Some examples of carbonated drinks are Coke, Pepsi and Sprite.

Tap Water
Tap water so that to be used as a control as it is the ‘purest’ among all the water types that we are planning to use.We will use the tap water and compare it with the rest to find out how the other types of water affected the growth of the Hydrilla Plants.

Pond Water
Water taken from our school’s eco-pond will be used as it is a form of ‘natural water’. As the pond water has many different minerals and micro organisms in it, it might affect the growth of the Hydrilla Plants.

Alkali Water
As Alkali Water is more towards the Alkaline side of the ph Scale, there is a chance that it would be used as we suspect that the presence of Alkali water might or might not aid the plant’s growth.


We would be testing on Hydrilla plants, with the hypothesis: The investigation of how the type of solution would affect the plant’s growth

After setting up the experiment, we would leave the plants at the science under table light, so as to ensure that the solution of the plant is the only independent variable in the set-up.

We would gather all the required materials and beginning of the week, leaving the plant to test for 5 days.

Water is a resource that is getting scarce, we are testing to find out that in the occasion that freshwater reaches a minimum, are able to plant aquatic plants in different areas, much like hydroponics for land plants.

We are testing 4 different setups - alkaline water, tap water, carbonated water and pond water, to see if hydrilla will grow differently in such solutions.

We use hydrilla plants instead of other plants as it is quicker to get results from them compared to other plants.

We would use data loggers as oxygen level detectors, starch test, the physical features(height) of the plant to determine whether the plant is able to grow in the different solutions, with the tap water as our control.


Independent variable
The type of water the hydrilla plant is in.

Dependent variable
The height and amount of oxygen produced by the plant.

Constant variable
The type of glass amount of water in the glass, place the experiment is in


Armstrong, S. (2013, JULY 09) “Gardening-know-how” Gardening-know-how retrieved, from

Langeland, K. (2013, JULY 09) Hydrilla verticillata "The Perfect Aquatic Weed" retrieved, from

Luis, A. Catherine, M. Poss, James. Donald, A. (2013, JULY 09) “Salinity and Alkaline pH in Irrigation,Water Affect Marigold Plants: II. Mineral Ion Relations” Hort Science retrieved, from

Morris, T. (2013, JULY 09) “Acid Rain and plant growth” Fullerton College. Retrieved from

Royle, L. (2013, JULY 09)  “Hydrilla verticillata” New York Invasive Species Information retrieved from

What is that ingredient (2013, July 09). “What is that ingredient” Retrieved from

Whiting, D. (2013, JULY 09) “Plant Growth Factors: Water” Colorado State University retrieved, from

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