Core Practical 7- 13/05/22
Core practical 7 - investigate plant mineral deficiencies
Aim : To investigate the effect of plant mineral deficiencies
Introduction
There are at least 16 elements that are considered necessary for the growth of green plants,
which includes carbon, hydrogen and oxygen from the air as well as nitrogen, magnesium,
calcium from the soil. An element is said to be essential if the plant cannot completely live
without it and if the disease that develops in its absence is curable only by that element (U.
S. Department of Agriculture, 1957). Based on their requirement, these nutrients have been
classified as macronutrients (N, P, K, Ca, Mg and S) because they are required at higher
concentrations and micronutrients (Fe, Zn, Mn, Cu, B, Mo and Cl) which are required at
lower concentrations (Pandey, 2018).
The mineral nutrient elements play essential roles such as constituent of cell structures and
cell metabolites, in cell osmotic relations and turgor-related processes, energy transfer
reactions, enzyme-catalysed reactions and plant reproduction. Plant productivity depends on
the efficient discharge of these functions (Pandey, 2018). Soil, a complex substrate, acts as
a storehouse of nutrients and water for plant growth. Plants have extensive root systems for
the nutrient uptake from the soil : nutrients move towards the roots by following certain
mechanisms of transport, which include mass flow, diffusion and root interception. The
nutrients thus reaching the roots are absorbed by plants either actively by spending energy
or passively by no involvement of energy (Karthika, Rashmi and Parvathi, 2018).
Nitrogen has many functions in plants. It is an essential element in amino acids that affect
plant proteins which are for growth and development of vital plant tissues and cells like the
cell membranes and chlorophyll. Nitrogen is also a component of nucleic acid that forms
DNA which is vital for transfer of traits that aid in survival. It is also essential in plant
processes such as photosynthesis (Tajer, 2016).
Magnesium is required for chlorophyll formation and plays a key role in photosynthetic
activity. Moreover, it is involved in carbohydrate transport from source-to-sink organs.
Hence, sugar accumulation in leaves that results from the impairment of their transport in
phloem is considered as an early response to Mg deficiency. The most visible effect is often
recorded in root growth, resulting in a significant reduction of root/shoot ratio (Farhat et al.,
2016).
Calcium is required for various structural roles in the cell wall and membranes, as a counter‐
cation for inorganic and organic anions in the vacuole, and as an intracellular messenger in
the cytosol. Calcium is taken up by roots from the soil solution and delivered to the shoot via
the xylem. It may traverse the root either through the cytoplasm of cells linked by
plasmodesmata (the symplast) or through the spaces between cells (the apoplast) (WHITE,
2003).
, Core Practical 7- 13/05/22
Hypothesis
The bean in the solution containing all minerals should be the most grown with no
abnormalities and appear healthy.
A nitrogen deficiency will translate to the reduction of chlorophyll synthesis influencing the
plant colour. Visual symptoms of nitrogen are characterised by chlorosis progressing from
light green to yellow as the plant cannot produce chlorophyll in sufficient quantities due to
the lack of nitrogen (Tucker, 2015). In addition, a plant without enough nitrogen will be
smaller than it should be and its stems will lignify sooner than it should, that is, to dry out and
become woody sooner than normal. Usually, the old leaves will be the first to show this
chlorosis and yellowing, since the plant will mobilise the nitrogen it has available to the new
areas of greater growth (Anderson, 2021).
The solution lacking magnesium will cause the bean plant to show symptoms of magnesium
deficiency which include interveinal chlorosis that causes the leaves to yellow while its veins
remain green. The leaf margins will turn a reddish or purple in colour as well as leaf
necrosis, slow growth and reduction of root growth (Greenway Biotech, Inc., n.d.).
Calcium deficiencies cause deformation and dying of root tips as well as yellowly chlorosis
throughout the leaves. Growth is slowed and new growth begins to curl forming parachute
shaped leaves. (Plone site, n.d.)
Risk assessment
Hazard and risk Safety measure
Biohazard may cause contamination Use disinfectant and wash hands
thoroughly after handling.
Sharp object is used to poke a hole through Handle carefully. Put away immediately
the aluminium. This may cause cuts after use.
Glasswares such as test tubes are fragile Take care when handling and keep away
causing them to break easily. They have from the edge of surfaces.
very sharp edges when they’re broken, this
may cause skin injury
Variables
Independent variable : the type of nutrients present in the solution that the plants are
growing in
Dependent variable : the length of the stem of the plant and physical characteristics of the
plant
Control variables :
- Volume of solution used needs to be kept the same as changing the volume would
affect how much access the roots have to the solution and would therefore affect the
growth. Every test tube was filled 9/10th of the way. The solutions will be topped up
when the levels go down in order to keep that same volume
