Josephine Bloggs 1234 56711 Lab group X
Lab Report: The effect of phosphorus nutrition on the growth of corn, Zea mays.
Introduction
Phosphorus (P) is an important nutrient for all plants. It is one of the nine
essential plant macronutrients and has important functions in energy carrying
compounds ATP and ADP, nucleic acids and phospholipids (Raven et al, 2013).
Plants that do not get enough phosphorus turn dark green or purple, have stunted
growth, and lose their oldest leaves (Raven et al, 2013, Table 29-2). In crop plants,
insufficient P leads to a low yield (Russell 1989). Phosphorus is taken up from the
soil by a plant’s roots, so the level of P in the soil has a large influence on plant
growth. Many Australian soils are very low in P, and so phosphorus is applied as
superphosphate fertilizer (CSBP, 2001). In sandy soils, such as those near Perth, this
is nearly always necessary.
This experiment examined the effect of adding P on the growth of corn (Zea
mays). This is a common market garden crop grown in the Metro area. Our prediction
was that adding P to the soil will increase the rate of growth and the harvest of corn
grown in a local soil.
Methods
Soil was obtained from a market garden in Wanneroo. It was steam- sterilised
and placed in 200mm pots, in which corn seeds were sown as described in Koenders
(2009). P was applied, and the corn was grown and harvested, as described in
Koenders (2009), with the exception that rates of fertiliser application in this
This is the format to use for an in-text citation. You need to cite the sources of information you use.
A lab report has required sections. The introduction includes background information as well as a statement of the aim or a prediction.
This makes a clear prediction for the experiment. Using it makes it easier to write a conclusion later
The scientific name should be in italics.
If you use methods that someone else devised, then cite their paper. Don’t re-write the whole lot.
The name of the author is clearly indicated in the header.
Josephine Bloggs 1234 56712 Lab group X
experiment have been converted to the standard format of kilograms per hectare
(kg.ha-1)
Results
Addition of a higher level of P had a large effect on plant growth (Table 1).
Plants with no P were very short, produced few or no cobs (Table1) and in general
had a low yield. Plants with applied P had the same mean number of cobs per plant,
but differed greatly in the yield of grain. The differences in yield levels between 0
and 26 kg.ha-1 was highly significant at (t=122.41, df = 18, p=0.05), as were those
between 0 and 39 kg.ha-1 (t=146.8) and 26 and 29 kg.ha-1 (t= 64.0).
Table 1. Effect of P application on plant size and yield of corn.
Level of Phosphorus
applied
(kg.ha-1)
Mean plant height
(cm)
No of cobs/plant Grain yield
(kg.ha-1)
0 55 0.375 1345
26 157 1.5 2921
39 176 1.5 3259
Discussion
It is very clear that addition of P to the soil increases plant growth and yield.
This result is consistent with the results of previous experiments that have shown
similar effects in many different species (Raven et al, 2013) and with the predictions
in this experiment.
This is a correct use of SI units…but there is a fullstop missing from the sentence!
Note how the table is referred to. It is not necessary to say “Table one shows that…”
The results are summarised in text, not just presented as a set of numbers.
The results of the statistical test are included – but not the calculations!
The table has a title that explains its contents.
Each column has a heading and gives the units in which the number are measured
Puts the results in context of the experiment’s aims and design, and other knowledge. See the list of specific items in the module’s description of this section.
The discussion does not repeat the results, but considers what they mean.
The results section does not include raw data, only summary statistics (mean, standard deviation etc)
Josephine Bloggs 1234 56713 Lab group X
Phosphorus has a number of important roles in the plant (Raven et al, 2013).
Plants that are deficient in P cannot grow properly, as they are unable to transport
energy in the form of ATP and ADP and so cellular metabolism is limited. they are
also less able to produce new cell membranes, as these also contain a large amount of
P in the form of phospholipids. In fact, it is quite possible that the mebranes degrade
over time and the cells die (Campbell et al, 2012).
P limited plants also lose their lower leaves, which is due to the translocation
of P from these leaves into the tissues where P is required. One of the major places
where P is needed is in the production of fruits and seeds, for new cell membrane and
DNA production as well as the production and transfer of energy. In the current
experiment the yield of corn seeds was much lower in plants with low P than where P
was provided, due to this effect. However it is not possible to comment on the levels
of P within the actual tissues as this was not measured.
It appears that there was not much difference between the production of corn
cobs between the two higher rates of P application. Corn plants only ever produce
two cobs at a maximum, so the biggest difference was in the production of none in
plants with no P added. It is also possible to say based on these results that the effect
of P was on the number of kernels and their weight within each cob in the 26 kg.ha-1
and 39 kg.ha-1 plants.
References
Campbell et al (2012). Biology: An Australian Focus 7ed. French’s Forest: Pearson
Education Australia
The student should have cited a reference for this information!
A shortcoming is identified and acknowledged, but not over- emphasised.
Only includes books and papers that you have referred to. Is not a bibliography!
This is not the correct format. All authors must be listed and in the order they are given on the paper/book cover. The title should be italicised.
Josephine Bloggs 1234 56714 Lab group X
Koenders, A. (2009) SCB1234 Biology Unit Handbook. Joondalup: Edith Cowan
University.
Raven, P.H., Evert, R.F., & Eichhorn, S.E. (2013). Biology of Plants. 8th ed. New
York, NY: W. H. Freeman & Assoc.
Appendix one: Calculation of t .
Example calculation of t values
Dataset 1: Yield and P rates of corn plants
P.rate Yield 0 1349.314 0 1375.269 0 1348.651 0 1361.168 0 1292.773 0 1278.519 0 1307.385 0 1290.501 0 1308.491 0 1392.21 26 2917.99 26 2927.51 26 2922.52 26 2933.661 26 2940.431 26 2911.618 26 2925.5 26 2904.873 26 2924.086 26 2936.097
Mean yield of group 1 (0 kg.ha) = 13304.281/10 = 1330
This reference is correct.
This is where to put raw data and calculations when required.
Notice how this is not a table- it’s just the listing of the raw data. The table created for the calculation of t are tables – they introduce new ideas to the raw data.
The student has shown how she worked out the mean.
There is a reference missing here. Can you find the other missing one?
Josephine Bloggs 1234 56715 Lab group X
Variance group 1
= ((1349 – 1330)2 + (1375 – 1330)2 + (1348 – 1330)2 + ….) / 9 = 1575.584
Mean group 2 (26 kg.ha) = 2917 + 2927 + …./ 10 = 2924
Variance group 2
= ((2917.99 – 2924)2 + (2927.51 – 2924)2 + (2922.52 – 2924)2 + ….) / 10-1
=119.984
Calculate value of t
= (|1330-2924|) / √ (1575.58/10 + 119.984/10)
= 1594/ √ 169.58 = 1594/13.02
= 122.42
The student has included the formula
While the student has calculated t she has missed something very important – she has not listed the critical value that she looked up on the statistical tables!
