Nutrient Deficiencies in Tomatoes
by Robert Kosinski
You are testing 4 null hypotheses about plant biomass
4 null hypotheses about leaf blade SCC. In each case, these are that
dependent variable (biomass or SCC) is the same in control plants and
either nitrogen-, phosphorus-, iron-deficient plants
or plants grown in distilled water after 4 weeks of growth. It would be possible to reject some of the 8
and to fail to reject others. Several of the nutrient deficiencies are
supposed to cause stunting of the plant, but the information below
that not all of them are supposed to cause a decrease in SCC. In some
an increase in SCC is expected, at least in young leaves, because the
hurts leaf growth more than it hurts chlorophyll production. This gives
small, intensely green leaves. Therefore, read the background and make
intelligent predictions about the effect of nutrient deficiency on both
biomass and SCC.
General principles of plant
Tomatoes in nutrient
The 2013 plant appearance results
Problems in 2013
Some Remarks about Your Paper
This Web site does not present numerical results. These results are available in spreadsheet form at the bottom of this site, and it is up to you to do the statistical analysis using the chi-square median test (also downloadable from this site). There are several ways to present the data; you make
decision, but remember the guidelines you were given in Biology 110
which are also given in Appendix II of your lab manual).
Nutrient Deficiencies in
Nutrient deficiencies can produce several effects:
growth, chlorosis (yellowing), and necrosis (death) of certain plant
In lecture we talked about a general feature of nutrient deficiencies.
Plants can withdraw an element from older tissue and send it to newer
so if a mobile element is lacking, the symptoms will appear on older
foliage first (Salisbury and Ross, 1992, p. 129). That is, new leaves
look green and healthy while older leaves may be yellow and drooping,
even dead. On the other hand, if the
element is immobile, the effects will show up first in new
foliage. In our experiment, N and P were considered mobile elements
and Fe was considered immobile. Chlorosis of new foliage (but not old
on some of the -Fe plants was seen in 2010 and 2011, but not very often in 2012 or 2013.
Figure 1. A stunted, chlorotic, -Fe tomato on April 7,
2003. The old leaves are green and the new leaves are bright yellow.
Iron is an immobile element.
Tomatoes in Nutrient
Tomatoes (Lycopersicon esculentum) are a good
for nutrient deficiency experiments because they are easily grown in
lab and produce obvious symptoms of nutrient deficiency on their
Each growth stage of tomato has its own nutrient requirements; our
tomatoes (40-70 days old while we were growing them) were in the stage
called vegetative growth, prior to flowering and fruit set. During this
stage, tomato increase in mass is mainly in the leaves. In contrast, at
harvest, about 3/4 of tomato biomass is in the fruit (Wilcox, 1994).
are known as a "hungry" crop that requires large amounts of nutrients,
The remainder of this section will be background
on the specific nutrient deficiencies we used. I cite published
but more background on nutrient deficiencies in tomatoes can
Taiz and Zeiger, a recent plant physiology book.
University of Massachusetts at Amherst, which has a Web site for an
organic gardening course that shows pictures of some tomato nutrient
Although nitrogen gas is abundant in the atmosphere,
is the element that is most commonly deficient in soils because only fixed
nitrogen (nitrate or ammonium) is useable by plants. Nitrogen makes up
about 1-5% of plant dry weight (Bergmann, 1992, p. 86), and has so many
roles in proteins, nucleic acids, and many other macromolecules that
primary effect of nitrogen deficiency is stunted growth. Because
is necessary for chlorophyll formation but can be easily moved in the
another obvious symptom is yellowing of older leaves (Salisbury and
1992, p. 130; Bennett, 1994; ). Nitrogen deficiency tends to retard
growth and accelerate flowering, although yields of fruit are reduced
the case where nitrogen is adequate. One reason for this is that
deficiency also has hormonal effects on the plant, retarding cytokinin
synthesis and accelerating synthesis of abscisic acid, the "hormone of
stress and dormancy." This ages the plant rapidly and reduces its
(Bergmann, 1992, p. 88).
Tomatoes suffering from nitrogen deficiency tend to
rigidly upright, with hard, thin stems and small leaves. Leaves are
and then wither. Flowers fall prematurely (Bergmann, 1992, p. 90).
Figure 2. Early nitrogen deficiency in tomato. Note
that is more intense between the veins than along the veins (Bergmann,
1992, p. 392).
Figure 3. Left: the same interveinal chlorosis in our -N
on April 7, 2003. Right: Chlorotic -N leaves compared with a "Complete"
leaf, 12 April 2005.
Phosphorus is the second most common limiting nutrient
soils. It is both taken up and used as phosphate ion. Perhaps the most
important structural use of phosphorus is in phospholipids in
Phosphorus also has many other hereditary and metabolic roles (in DNA
RNA, ATP, NADP, etc.), and so lack of phosphorus hampers cell
inheritance, and normal metabolism. The result is general stunting
and Ross, 1992, p. 131; Bennett, 1994). Some plants without any
input can "recycle" phosphorus from organic molecules for amazingly
periods; Bergmann (1992, p. 98) cited an 1882 report that an oak tree
in phosphorus-free medium was able to survive for three years with no
but then finally died. Perhaps because of this recycling, respiration
tend to be higher in phosphorus-deficient plants. Phosphorus deficiency
retards leaf growth, but not chlorophyll synthesis, so leaves of
plants tend to be darker green than leaves of control plants, and this
may make them look healthier. Bergmann (1992, p. 98) remarked that
deficiency is nearly impossible to spot in the field unless control
without phosphorus deficiency are available for comparison. Phosphorus-deficient leaves can also have a deposition of purple anthocyanin pigment on their undersides.
Bergmann (1992, p. 103) reported that typical
of phosphorus deficiencies in tomatoes include stunting, dark green
leaves and yellowing older leaves, curled leaflets, thin stems with
coloring, and poor fruit production. Tomatoes are sensitive to lack of
Figure 4. Left: Tomato with phosphorus deficiency. About the
symptom apparent here is the thin stem that could not support the plant
(Roorda van Eysinga and Smilde, 1981, p. 12). Right: Deposition of purple pigment in -P leaves on 2 April 2010. We only saw this purple pigment in the distilled water plants this year.
Iron is our only micronutrient, and a largely immobile
Therefore, it must be taken up continuously. Iron is part of certain
and enzymes that participate in electron transport (especially the
Its role here is very important, because it is often iron itself that
and releases electrons, changing between the Fe+3
to Fe+2 states
it does so (Salisbury and Ross, 1992, p. 132). Iron is also necessary
chlorophyll synthesis and protein synthesis (Bennett, 1994).
Iron is an immobile element in plants because it is
in insoluble forms such as iron oxides and an iron-protein complex
phytoferritin, which is stored in chloroplasts. It is difficult for
insoluble molecules to enter the phloem for transport. Therefore, when
iron deficiency strikes, the newer leaves tend to suffer first,
becoming chlorotic. This starts in the areas between the veins, and
may involve the whole leaf as chlorophyll synthesis in the new leaf is
disabled (Salisbury and Ross, 1992, p. 132). Because of its role in
iron-deficient plants have lowered metabolic rates.
Figure 5. Iron-deficient tomato with characteristic
on newest leaves, especially between the veins (Bergmann, 1992, p. 552).
While we might think that plants grown in distilled water would have all the nutrient deficiency symptoms above, our results seem to show that distilled water mostly produces the symptoms of nitrogen deficiency, stunting and chlorosis of the leaves. This emphasizes the important role that nitrogen plays in plant growth. It also shows how nutrient deficiencies could interact. If the plant cannot grow without nitrogen, its need for the other nutrients is so reduced that it doesn't show their deficiency symptoms. The Distilled Water plants also had a tendency toward purple leaf veins, a phosphorus deficiency symptom. The -N plants did not have purple veins and were not quite as chlorotic as the Distilled Water plants.
Figure 6 shows a comparison of the Distilled Water and -N tanks in 2009. Figure 7 shows a comparison of the Complete and Distilled Water leaves, showing the purple veins in the latter.
Figure 6. The Distilled Water treatment (left) compared with the -N treatment (right) on 30 March 2009. The Distilled Water plants looked worse and had purple pigment deposited along their leaf veins.
Figure 7. A Complete leaf and a Distilled Water leaf on 8 April 2009. Note the intense chlorosis and purple veins of the Distilled Water leaf.
The 2013 Visual Results
The 2013 tomatoes were planted from 12-14 March 2013,
were harvested from 9-11 April. This is the second year we used the hydroponic recirculators. In the past we used aquaria with the plants in styrofoam floats. The recirculators worked OK, but they made photography difficult because you couldn't see just one treatment clearly (except the distilled water treatment, which was separate).
Figure 8. One group of Complete, -N, -P, and -Fe recirculators on 15 March
2013. All the treatments were visually similar, and looked healthy.
Figure 9. The distilled water recirculators on 16 March 2012. The distilled water plants at this early date had the same size and appearance as the other plants.
Figure 10. By March 23, all the plants still looked healthy, but the growth of the distilled water plants was lagging behind the others.
Figure 11. The distilled water plants on March 23. Compare with Figure 10.
Figure 12. Some leaves in the distilled water treatment were chlorotic by March 23.
Figure 13. By March 29, severe chlorosis was affecting the old leaves of some plants in the -N treatment.Note how the chlorosis affects areas farthest from veins first.
Figure 14. By April 5, some of the -Fe plants showed severe chlorosis of the new leaves. Note the contrast with a fragment of Complete plant leaf.
Figure 15. The non-distilled water recirculators on 8 April. Compare the size of the plants with the size in Figure 10.
Fig. 16. A distilled water plant on 8 April, showing the chlorosis of nitrogen deficiency and the purple leaf veins of phosphorus deficiency. No plants in any of the other nutrient treatments looked like this.
Fig. 17. The distilled water plants on April 8. Some did grow, but they were all stunted and chlorotic compared to the other treatments.
Problems in 2013
The experiment in 2013 had mixed results. The effects of lack of N (seen in the -N and Distilled Water treatments) on growth were very marked. There were not such marked effects of P and Fe deficiency (although the results might still be statistically significant). The effects on SCC were more subtle, although the means seemed to vary in the expected way, with Completes highest and -N and Distilled water low. Some SCC results might be significant.
Another problem that has bedeviled this experiment for years is variability between the plants
the same treatment. The picture below shows two contrasting Complete
plants in 2003.
Fig. 18. Control plants if very different sizes held by
Jennifer Zurosky and Omar Ladhani in 2003. Note the root mass of the
held by Omar.
This variability can cause a
chi-square test to declare a non-significant result. For example, say that the -N treatment is obviously smaller than the Complete treatment, but both treatments have a few
big plants and lots of small ones. The reason the Complete treatment looks more impressive is because its "big" plants dwarf the bigger plants in the -N treatment. However, the chi-square
median test makes its decisions based on the numbers of plants in each
above and below the median of the combined data set. If the median of that data set (Completes plus -N here) is 15 g, a plant that is
in -N and a plant that is 160 g in the Complete treatment are considered to be the same--they are both above the
median, and that's all. How far above the median those big Complete
plants are would not matter.
This brings up a general principle of statistics. In order to declare a significant difference, we must have a difference
between the means, but we also must have small variability within each
treatment. The variability within each treatment often prevented a
significant difference from being declared in the past. You will have to determine whether that is true this year as well.
The 2013 Data
...is on a results spreadsheet that must be downloaded. The chi-square median test spreadsheet and a spreadsheet of test data can also be downloaded. The test data will allow you to be assured that you are using the median test correctly. Finally, there is a set of directions on how to use the median test spreadsheet.
Good luck with your plant nutrient report. It must be uploaded by11:59 PM on 25 April 2013.
Bennett, W. F. 1994.
Plant nutrient utilization and
plant symptoms. Pp. 1-7 in W. F. Bennett (Ed.), Nutrient
and Toxicities in Crop Plants. APS Press, St. Paul, MN.
Bergmann, W. 1992. Nutritional
Development, Visual and Analytical Diagnosis. Gustav Fischer
Roorda van Eysinga, J.
P. and K. W. Smilde. 1981. Nutritonal
Disorders in Glasshouse Tomatoes, Cucumbers and Lettuce. Centre
Agricultural Publishing and Documentation, Wageningen, the Netherlands.
Salisbury, F. B. and C.
W. Ross. 1992. Plant
4th Ed. Wadsworth Pub. Co., Belmont, CA.
Wilcox, G. E. 1994.
Tomato. Pp. 137-141 in
W. F. Nutrient Deficiencies and Toxicities in Crop Plants. APS
St. Paul, MN.