General enquiries on this form should be made to:
Defra, Science Directorate, Management Support and Finance Team,
Telephone No. 020 7238 1612
E-mail:
[email protected]
SID 4


Annual/Interim Project
Report for Period 2006/2007
ACCESS TO INFORMATION
The information collected on
this form will be stored
electronically and will be
required mainly for research
monitoring purposes.
However, the contents may be
used for the purpose of
notifying other bodies or the
general public of progress on
the project. Defra may also
disclose the information to any
outside organisation acting as
an agent authorised by Defra
to process research reports on
its behalf.
Defra may be required to
release information, including
personal data and commercial
information, on request under
the Environmental Information
Regulations or the Freedom of
Information Act 2000.
However, Defra will not permit
any unwarranted breach of
confidentiality or act in
contravention of its obligations
under the Data Protection Act
1998. Defra or its appointed
agents may use the name,
address or other details on
your form to contact you in
connection with occasional
customer research aimed at
improving the processes
through which Defra works
with its contractors.
Project details
1. Defra Project code
2. Project title
Sustainable Phosphorus Fertilisation of Potatoes
3. Defra Project Manager
4. Name and
address of
contractor
5. Contractor’s Project Manager
6. Project:
Laura Pleasents
University of Warwick
WarwickHRI
Wellesbourne
Warwick
Warwickshire
Postcode CV35 9EF
Dr John P. Hammond
start date .................
01 April 2004
end date ..................
31 March 2008
This form is in Word format
and boxes may be expanded
or reduced, as appropriate.
SID 4 (Rev. 3/06)
HH3504SPO
Page 1 of 9
Scientific objectives
7.
Please list the scientific objectives as set out in the contract. If necessary these can be expressed in an
abbreviated form. Indicate where amendments have been agreed with the Defra Project Manager, giving the
date of amendment.
01. To perform three field trials to assess the potential of struvite as an alternative to chemical P fertilisers
(within 40 months)
02. To shortlist P-responsive genes in leaves of Arabidopsis thaliana (within 8 months)
03. To shortlist sequenced transcripts of between 20 and 50 P-responsive genes expressed in potato
leaves (within 23 months)
04. To design, manufacture and test a prototype Potato Chip (within 30 months)
05. To produce and test an alpha-design Potato Chip (within 48 months)
Summary of Progress
8.
Please summarise, in layperson’s terms, scientific progress since the last report/start of the project and
how this relates to the objectives. Please provide information on actual results where possible rather
than merely a description of activities.
Aims
The UK horticultural and agricultural industries rely on large inputs of phosphate (P) fertilisers to maintain
crop yields and quality. However, the use of non-renewable, chemical P fertilisers is unsustainable, and
the alternatives to chemical P-fertilisers must be identified as an immediate priority. Preliminary
observations indicate that a natural waste-product, struvite [(NH4)Mg(PO4)·6(H2O)], could provide an
alternative to chemical P fertilisers for crop production. Struvite precipitates out of sewerage sludge and
can be reclaimed from animal wastes. Its disposal to landfill is expensive, and raises the risk of local
pollution. Thus, the use of struvite as a fertiliser is an attractive proposition. The first aim of this project is
to assess the potential of struvite as a P fertiliser for potatoes and to compare the effectiveness of struvite
with a chemical P fertiliser, triple super phosphate (TSP), in field trials on P gradients (Defra soil P indices
between 2 and 9) established at HRI-Wellesbourne.
Excessive P fertiliser applications are also costly, and can lead to unnecessary pollution. Inefficient P
fertilisation is a particular problem for the potato crop, which utilises little of the P fertiliser applied (RB209:
Defra Fertiliser Recommendations). Often more P is applied than is required because chemical assays of
soil and plant P are unreliable. Novel biosensor technologies, exploiting knowledge of the changes in plant
gene expression that occur under P starvation, could better inform P fertiliser applications. These
technologies provide an insight into the immediate physiological P requirement of the crop. The second
aim of this project is to develop an oligonucleotide microarray ("Potato Chip") to monitor the expression of
diagnostic genes in the youngest fully expanded leaves of potatoes and, thereby, deduce the P status of
the potato crop. In practice, these Potato Chips may become a management tool for precision agriculture.
They will allow farmers to monitor the immediate physiological P status of their crops in order to optimise
the application of P fertilisers.
Scientific Progress since April 2006.
Assessing the suitability of struvite as a source of phosphorus for agriculture
As part of Objective 01, the third and final year’s field trial investigating the suitability of struvite (a
renewable source of phosphorus) as an alternative to chemical phosphate (P) fertilisers was completed.
Potatoes were grown on P gradients (Defra soil P indices 3 to 9) established using either struvite or triple
super phosphate (TSP) as the source of P. Seed tubers were sampled pre-planting, and potato plants
(shoots, roots, seeds and tubers) were harvested at tuber initiation. Potato tubers were then harvested at
commercial maturity. All samples were analysed for fresh and dry weight and mineral concentrations (N,
P, K, Mg, Ca, B, Cu, Mn, Fe, Zn, S, and Na).
The fresh and dry weights of shoots from potato plants harvested at tuber initiation increased significantly
with increasing P supply when P was supplied as struvite, but not when P was supplied as TSP. This is in
contrast to the previous two years field trials (Figure 1A). However, there was no effect of the source or
SID 4 (Rev. 3/06)
Page 2 of 9
level of P supplied on the dry weights of potato roots or tubers. The amount of P supplied had a significant
(P<0.05) effect on the shoot concentrations of N, P, K, Mg, Ca, Cu, Zn, B and S, with the concentration of
N (struvite treatment only), P and Mg increasing with increasing soil P index and the shoot concentrations
of K and Ca decreasing with increasing soil P index on struvite treated plots (Figure 1B, C, D, E, F). The
increase in N with increasing amounts of struvite supplied, in contrast to the TSP treatment, is probably
due to the fresh application of struvite prior to planting, to maintain the levels of P, consequently supplying
N in the process. The source of P had a significant effect on shoot P, K, Ca, Mg and Mn concentrations,
with shoot K concentrations declining with P level for potato plants supplied with struvite, but remaining
relatively constant for potato plants supplied with TSP (Figure 1D). These are similar to observations
made in the first and second year’s field trial.
Figure 1. Potato shoot dry weights (A), shoot P concentration (B), shoot Mg concentration (C), shoot K
concentration (D), shoot Ca concentration (E), and shoot N concentration (F), at tuber initiation for plants
supplied with either struvite (black bars) or TSP (white bars) as the source of phosphorus. Potatoes were
grown under field conditions at Warwick HRI, Wellesbourne UK in 2006.
On average the shoot concentrations of N, P, Mg, Ca, B, Cu Fe and S were higher in the shoots of plants
supplied with struvite, compared to the shoots of plants supplied with an equivalent amount of TSP. The
shoot concentrations of K were significantly (P<0.05) higher in the shoots of potato plants supplied with
TSP compared to the shoots of potato plants supplied with struvite (Figure 1D). This is consistent with the
first and second year’s field trial, despite additional K being supplied to the struvite treated plots. This
SID 4 (Rev. 3/06)
Page 3 of 9
suggests struvite may affect either the availability of K in the soil solution or the ability of plants to take up
K from the soil solution. Further work is required to investigate this phenomenon. Interestingly, the shoot
concentrations of Mn were significantly (P<0.05) higher in the shoots of potato plants supplied with TSP
compared to the shoots of potato plants supplied with struvite.
Figure 2. Commercial yield of potato tubers (A), tuber P concentration (B), tuber Mg concentration (C),
tuber K concentration (D), tuber N concentration (E), and tuber Ca concentration (F) at commercial
maturity for plants supplied with either struvite (black bars) or TSP (white bars) as the source of
phosphorus. Potatoes were grown under field conditions at Warwick HRI, Wellesbourne UK in 2006.
When assayed at commercial maturity, there was no significant (P<0.05) difference in the commercial
yield between plots supplied with TSP and plots supplied with struvite. In the first year’s field trial, potatoes
supplied with TSP had significantly higher commercial yields at all levels of P supply and in the second
year’s field trial there was no significant (P>0.05) difference between the treatments. It should be noted
that in the first year the struvite and TSP had only recently been applied, potentially make some nutrients
more available. Both sources of phosphorus elicited a significant (P<0.05) response in commercial yield in
response to the amount of P supplied. Tuber yields from potatoes supplied with struvite increased from a
minimum of 35.1 t ha-1 at a soil P index of 3 to 45.9 t ha-1 at a soil P index of 9. Tuber yields from potatoes
supplied with TSP increased from a minimum of 34.9 t ha-1 at a soil P index of 3 to 47.2 t ha-1 at a soil P
index of 9 (Figure 2A). There was no significant difference in the yield of ware grade tubers and the yield
of tubers smaller than ware grade between potato plants supplied with TSP or struvite. However, potato
SID 4 (Rev. 3/06)
Page 4 of 9
plants supplied with struvite produced significantly (P<0.05) more tubers larger than ware grade than
potato plants supplied with TSP (data not shown).
The effect of soil P index had a significant effect (P<0.05) on tuber P concentration with tuber P
concentration increasing with soil P index (Figure 2B). There was a significant effect of soil P index
(P<0.05) on tuber Mg, N, Ca, Cu, Zn, S and Na concentrations (Figure 2C, D, E, F). Consistent with the
first two field trials, there was a significant difference (P<0.05) in tuber K concentration between
treatments, with potato plants supplied with TSP producing tubers with higher concentrations of K than
potato plants supplied with struvite (Figure 2D). There was also a significant effect of P source on tuber N
and Ca concentrations. Tuber Ca concentrations decreased with increasing soil P index for plants
supplied with struvite, but increased slightly in plants supplied with TSP (Figure 2F).
Figure 3. Average potato shoot dry weights (A), shoot P concentration (B), shoot Mg concentration (C),
shoot K concentration (D), shoot Ca concentration (E), and shoot N concentration (F), at tuber initiation for
plants supplied with either struvite (black bars) or TSP (white bars) as the source of phosphorus. Potatoes
were grown under field conditions at Warwick HRI, Wellesbourne UK over three years (2004-2006). Error
bar represents least significant differences of means (5% level) with n = 9 (3 plots per treatment x data
from 3 experiments performed over 3 years).
SID 4 (Rev. 3/06)
Page 5 of 9
Following the completion of the third and final field trial to compare the suitability of the struvite as a
source of phosphorus for agriculture, the data were analysed collectively. Data from samples collected at
tuber initiation were analysed using an ANOVA. With the exception of boron, there was a significant
(P<0.05) effect of trial year on all traits measured at tuber initiation. This highlights the significant influence
of environmental factors on the availability of nutrients to potato plants and their subsequent growth. At
tuber initiation, there was a significant effect of soil P index on shoot dry weight, with shoot dry weights
increasing with increasing soil P index for plants supplied with TSP or struvite, however there was no
significant difference between the two treatments (Figure 3A). The soil P index had a significant effect on
the shoot concentrations of N, P, K, S, Ca, Mg, B, Cu, Mn and Zn. Shoot P concentrations increased
significantly with increasing soil P index for plants supplied with either struvite or TSP (Figure 3B). Both
shoot N and Mg concentration increased significantly with increasing soil P index in plants supplied with
struvite, but not in plants supplied with TSP, as a consequence of the additional Mg and N in struvite
(Figure 3C, F). The shoot K and Ca concentrations both decrease significantly with increasing soil P index
in plants supplied with struvite, but not in plants supplied with TSP. This might be a consequence of the
additional Mg supplied with the struvite, which may act to reduce the availability of these cations in the soil
or reduce the ability of the plant roots to take them up. Further research into this phenomenon is required
with additional investigation on different soil types.
Figure 4. Average commercial yield of potato tubers (A), tuber P concentration (B), tuber Mg
concentration (C), tuber K concentration (D), tuber N concentration (E), and tuber Ca concentration (F) at
commercial maturity for plants supplied with either struvite (black bars) or TSP (white bars) as the source
of phosphorus. Potatoes were grown under field conditions at Warwick HRI, Wellesbourne UK over three
years (2004-2006). Error bar represents least significant differences of means (5% level) with n = 9 (3
plots per treatment x data from 3 experiments performed over 3 years).
SID 4 (Rev. 3/06)
Page 6 of 9
Data collected from samples taken at commercial maturity from the three trial years show there was no
significant (P<0.05) difference in the commercial yield between plots supplied with TSP and plots supplied
with struvite as their source of P (Figure 4A). This suggests that struvite is capable of supplying
phosphorus to the potato crop under agronomic conditions and enables the potato crop to produce
commercial yields similar to plants supplied with a commercial inorganic phosphate fertiliser. However,
these data should be treated with caution, given that 1) the occasion to occasion variation was significant
and commercials yields from struvite treated plots were not comparable to TSP treated plots in all years
and 2) these data are restricted to one field trial site, and it is likely that soil type and irrigation practices
could have a significant impact on the availability of P supplied by struvite. Both sources of phosphorus
elicited a significant (P<0.05) response in commercial yield in response to the amount of P supplied. Tuber
yields from potatoes supplied with struvite increased from a minimum of 37.6 t ha-1 at a soil P index of 3 to
45.0 t ha-1 at a soil P index of 8. Tuber yields from potatoes supplied with TSP increased from a minimum
of 37.4 t ha-1 at a soil P index of 3 to 47.3 t ha-1 at a soil P index of 8 (Figure 4A).
The effect of soil P index had a significant effect (P<0.05) on tuber P concentration with tuber P
concentration increasing with soil P index for both treatments (Figure 4B). There was a significant effect of
soil P index (P<0.05) on tuber Mg and N concentrations for plants supplied with struvite (Figure 4C, F).
Tuber K concentration was consistently significantly higher in tubers from potato plants supplied with TSP
compared to potato plants supplied with struvite (Figure 4D). Tuber Ca concentrations decreased with
increasing soil P index for plants supplied with struvite, but did not change greatly with soil P index in
plants supplied with TSP (Figure 4E). Further analysis will be completed on this data set including
comparisons between nutrients before the end of the project.
Development of a diagnostic microarray to determine plant P status
To identify genes from potato, which respond specifically to P deficiency (Objective 03), a custom potato
microarray was designed and built (Objective 04). This enables the direct identification of potato genes
that respond to P deficiency and avoids the need for first identifying genes in Arabidopsis that respond
specifically to P deficiency and then identifying orthologous genes in potato with available clones, which
has a low success rate.
This work has now progressed with the hybridisation of samples harvested at different time points
following the withdrawal of P from potato plants growing hydroponically under glasshouse conditions. and
also from field grown potato plants grown at different soil P indices as part of the comparison between
struvite and TSP sources of P. These data are currently being analysed and the expression of candidate
genes verified using quantitative PCR. In line with future milestones on the project, there have been
discussions with microarray manufacturers to identify suitable platforms for the production of the final
diagnostic microarray. The likely design will enable the analysis of up to 20 samples for the expression of
at least 100 genes on one microarray. This will make the costs per sample comparable to the mineral
analysis of a soil or plant sample.
The Potato Oligo Chip Initiative (POCI) led by Wageningen University, have recently validated and
released the final design for their oligonucleotide array that represents approximately 40,000 potato
transcripts. We have now taken delivery of these new arrays and will shortly begin hybridising the same
RNA samples used on the Potato Chips to these larger arrays. This will generate data for an additional
20,000 genes and validate the expression data for genes represented on both arrays.
Amendments to project
9.
Are the current scientific objectives appropriate for the remainder of the project? ................. YES
NO
If NO, explain the reasons for any change giving the financial, staff and time implications.
Contractors cannot alter scientific objectives without the agreement of the Defra Project Manager.
SID 4 (Rev. 3/06)
Page 7 of 9
Progress in relation to targets
10. (a) List the agreed milestones for the year/period under report as set out in the contract or any agreed
contract variation.
It is the responsibility of the contractor to check fully that all milestones have been met and to
provide a detailed explanation when they have not been achieved.
Milestone
Number
Milestones met
Target date
Title
In full
On time
01.04
Plant samples from second field
experiment analysed
01/08/06
Yes
Yes
01.05
Potatoes from third field experiment
harvested
01/10/06
Yes
Yes
03.04
Induction of short-listed potato genes
under P stress confirmed
01/05/06
Yes
Yes
04.01
Prototype potato chip designed
01/09/06
Yes
Yes
04.02
Prototype potato chip tested with fieldgrown material
01/10/06
Yes
Yes
(b) Do the remaining milestones look realistic? ..................................................................... YES
If you have answered NO, please provide an explanation.
NO
Publications and other outputs
11. (a) Please give details of any outputs, e.g. published papers/presentations, meetings attended during this
reporting period.
Publications and other outputs produced during reporting period (2006/2007) that contain data,
methodologies, or concepts developed, in part or in whole, in HH3504SFV.
Referred publications
Hermans C, Hammond JP, White PJ, Verbruggen N (2006). How do plants respond to nutrient
shortage by biomass allocation? Trends in Plant Science, 11, 610-617.
Hammond JP, Bowen HC, White PJ, Mills V, Pyke KA, Baker AJM, Whiting SN, May ST, Broadley MR
(2006). A comparison of the Thlaspi caerulescens and T. arvense transcriptomes. New
Phytologist, 170, 239-260.
Amtmann A, Hammond JP, Armengaud P, White PJ (2006). Nutrient sensing and signalling in plants:
potassium and phosphorus. Advances in Botanical Research, 43, 209-256.
Other Publications
White PJ, Wheatley RE, Hammond JP, Zhang K: Minerals, Soils and Roots. In: Potato biology and
biotechnology: advances and perspectives. Vreugdenhil D, et al., eds. Accepted for publication.
SID 4 (Rev. 3/06)
Page 8 of 9
Presentations and abstracts at scientific meetings
Hammond JP, White PJ, HC Bowen, RM Hayden, WP Spracklen (2007) Preparing and analysing
Agilent array data. Potato Oligo Chip (POCI) Workshop, Wageningen, Netherlands, 27th - 28th
March 2007.
Hammond JP, White PJ (2007) Phloem sucrose: Integrating phosphorus starvation responses.
Annual Main Meeting of the Society for Experimental Biology, Glasgow, April 2007.
MR Broadley, HC Bowen, JP Hammond, GJ King, MC Meacham, A Mead, G Teakle, PJ White (2007)
Natural genetic variation in the nutritional composition of Brassica oleracea. Annual Main
Meeting of the Society for Experimental Biology, Glasgow, April 2007.
S Ó Lochlainn, HC Bowen, R Fray, JP Hammond, GJ King, V Mills, PJ White, MR Broadley (2007)
Natural genetic variation in zinc (Zn) accumulation in Brassicaceae species. Annual Main
Meeting of the Society for Experimental Biology, Glasgow, April 2007.
Hammond JP, Broadley MR, White PJ (2006). Diagnosing phosphorus deficiency in crop plants by
monitoring changes in gene expression. In: Proceedings of the 3rd International Symposium
on Phosphorus Dynamics in the Soil-Plant Continuum, Uberlandia, MG, Brazil, 14th-19th May
2006, pp. 125-126.
Hammond JP, White PJ, Broadley MR (2006). P6.26 Developing transcriptional platforms for nonmodel plant species. In: Abstracts of the Annual Main Meeting of the Society for Experimental
Biology, April 2006. Comparative Biochemistry and Physiology, 143A (4 Supplement 1), S179.
HC Bowen, RM Hayden, WP Spracklen, PJ White, Hammond JP (2007) Targeting phosphorus
fertiliser applications to roots of wide row crops. Crop Science Seminar Series, Warwick HRI,
16th April 2007.
Hammond JP, White PJ (2007) Phloem sucrose: Integrating phosphorus starvation responses.
Departmental Seminar Series, Warwick HRI, 5th March 2007.
(b) Have opportunities for exploiting Intellectual
Property arising out of this work been identified? ............................................................ YES
If YES, please give details.
NO
(c) Has any other action been taken to initiate Knowledge Transfer?................................... YES
NO
If YES, please give details.
In addition to the scientific publications and presentations relating to this project, in 2006/2007 this
work was discussed at meetings with the British Potato Council at Warwick, the Defra Phosphorus
co-ordination meeting at Leicester and the Second Annual Meeting of the Solanaceae Research
Community in the UK. Aspects of this project were also discussed, including the diagnostic
techniques being developed and the transcriptional profiling work, in lecture courses at Nottingham
University (MR Broadley, JP Hammond, PJ White) and at the Comenius University, Bratislava (PJ
White) and in a departmental seminar at the University of Warwick (JP Hammond).
Future work
12. Please comment briefly on any new scientific opportunities which may arise from the project.
Declaration
13. I declare that the information I have given is correct to the best of my knowledge and belief.
Name
Position held
SID 4 (Rev. 3/06)
Professor S Bright
Director and Head of Department
Page 9 of 9
Date