Identify any differences that occurred, during the growth of hyacinths grown hydroponically, when different content of solutions were used.

Abstract

An experiment was carried out, to identify any differences that occurred, during the growth of hyacinths grown hydroponically, when different content of solutions were used. Over a period of eight weeks, data has been collated and analysed to find the most favourable solution for the best growth medium for hyacinths.

Introduction

It was required to research an area of environmental science, for this assignment, to develop independent scientific investigation. The aim was to collect relevant information, design an experiment, collect and record data. The data will then be analysed and conclusions will be drawn from this. As this is not an area that I am familiar with, I decided to opt for a simple experiment, with the intentions of progressing on to a more complex one in further investigations. After intensive background reading I decided to opt for something that I had some understanding of and thought that I would investigate the growth of plants. I felt this investigation could advance my subject knowledge and therefore improve my teaching in this area.

Primarily, I needed to formulate a hypothesis. As a novice, I was unaware that plants could be grown in water alone, and was interested to investigate how well this could be carried out. Therefore my hypothesis is:

The comparison of medium solutions, for growing hyacinths.

Winterborne (1997) suggests “plants grown in a hydroponic system can be given very exact and specific doses of nutrients….will develop optimum levels of appearance, yield and flavour” (p4)

I will endeavour to make predictions, and then discover the difference medium solutions make to the growing of hyacinths, by investigation and extensive reading. Primarily some background information is required before proceeding with the experiment.

Background Information

Harlen (1996) defines “ scientific activity is characterised by developing theories which fit the evidence available but which may be disproved when further evidence comes to light”(p5) This definition appears appropriate to my research, as it is a small research, which could be disproved by a larger investigation; however, this research has been beneficial to my understanding and knowledge, of teaching science. Halen goes on to say scientific literacy means “ functioning with confidence in relation to the scientific aspects of the world around, being able to look at something ‘in a scientific way’”(p7) which has been my aim.

Hyacinth Bulbs.

The definition of a bulb is any plant that stores its complete life cycle in an underground storage structure. The primary function of this underground storage a structure is to store nutrients reserves to ensure the plants’ survival. Bulbs are usually perennials. They have a period of growth and flowering, this is followed by a period of dormancy where they die back to ground level at the end of each growing season. The bulb can be categorized into five different types, which are:

True bulbs (tunicate and imbricate bulbs);
Corms;
Tubers;
Tuberous roots;
Rhizomes.

Hyacinths are true bulbs (tunicate bulbs). In the basal centre portion of the bulb are the leaves cradling a baby bud. Surrounding the bud is a white, meaty substance called the scales. In the true bulb the scales that contain all the food the bulb will need to flower and thrive. Anchoring the scales and the floral stalk that holds the bud is the basal plate. This plate at the bottom of the bulb also holds the roots of the plant. A thin outer skin called the tunic protects the whole bulb. This protects the scales from drying and from injury.

Drawing of a bulb.

Pictures of Bulbs

Bulbs grown hydroponically

When grown hydroponically, the bulb should be placed in conical shaped container so that the bulb can sit on the top and the water placed underneath so that the bulb can smell the water and send out roots. The bulb should never touch the water, as it will cause it to rot. The bulb should be put in a cool dark area (about 50°) until the roots are well developed. It is important not to store fruit near the bulb as ripened fruit releases ethylene gas which can kill or damage the flower that is inside the bulb. When the shoots are two inches tall, the roots should be well extended. Then the containers should be moved into slightly warmer temperature. After a few days, they should be moved to a sunny windowsill. The flowers should be turned a bit each day so that they do not lean towards the sun.

The term hydroponics was coined in the mid 20th Century. It is a term used to express a technique for growing plants in a soil less medium; the flooding of the Egyptian Nile is an example of hydroponics.

Hydroponics plants are grown in a static medium and fed water and nutrient. Plants that are grown in soil have to continuously develop their root balls in search of water, nutrients and air so the majority of plants available energy is spent on the lower root development restricting its upper growth. In hydroponics, the water, nutrient and air are mainlined directly to the root ball, freeing the plant to use its available energy in its upper leaf, fruit or flower development. As the roots of plants grown in soil-less medium do not need to constantly grow in search of nutrient; more plants can be grown in a smaller area. The solution that the plant is in must be aerated for optimal growth. If it is not aerated the plant will be in short supply of oxygen, and become anoxia. Anoxia inhibits the respiration of root cells and reduces nutrient uptake. The container that the plant is place should be dark to keep the light out. This is so that algae do not grow in the water and take some of its nutrients.

In 1860, Julius Sachs, a German botanist, demonstrated that plants could be grown to maturity in defined nutrient solutions without the use of soil. By the mid nineteenth century, Sachs and other colleagues became interested in discovering the minimal nutrients of a plant. Sachs devised an experimental system so that the roots grew in aqueous solution of mineral water. He then demonstrated the growth of plants to maturity using a nutrient solution containing six inorganic salts.