This document provides an overview of types and characteristics of field trials for evaluating crop varieties. It discusses the main types of variety trials, including progeny trials, observation trials, national/regional trials, on-farm trials, and demonstrations. For each type of trial, the document outlines their objectives, design considerations, and management practices. It also covers best practices for conducting variety trials, such as selecting trial sites, layout, data collection, and analysis. The overall purpose is to help researchers and technicians properly design and implement variety trials to effectively evaluate new crop varieties.

1. Types and Characteristics of Field
Trials
B. Badu-Apraku
Training course on Increasing the Capacity of Research
Technicians in Breeding.
July 27 to August 14, 2015, IITA-Ibadan, Nigeria

2. Outline of presentation
• Types of variety trials
• Conducting variety trials
Criteria for selecting an experimental field
Land preparation and fertilizer application
Demarcation and layout of field trials
Scheduling of the trial
Choosing appropriate checks
Border rows
• Management of Maize Variety Trials
• Data Collection in Maize Variety Trials
• Harvesting, shelling and trial packaging

3. Types of variety trials
There are five types of variety trials:
Progeny trials
Observation/preliminary trials
National, Regional or International Variety Trials
On-farm trials
Demonstrations

4. Progeny Trials
• Progeny trials involve large numbers of
progenies of a family type, such as:
– full-sib,
– half-sib,
– S1 lines.
• The progenies evaluated to identify those
that may be used to generate :
– synthetics
– experimental varieties,
– recombined to form an improved population in a
recurrent selection program.

5. Progeny Trials (Cont’d)
• Data obtained from progeny trials may be
used to estimate genetic variances and
covariances from which:
– heritability estimates,
– predicted responses to selection,
– genetic correlation coefficients,
– correlated responses to selection
• Progeny trials are normally researcher-
managed.

6. Observation/Preliminary trials
Observation or preliminary trials are used to
evaluate previously untested technologies in a
simple comparative manner with existing
technologies, usually on experimental stations
under close supervision to determine whether
they have any merit.
A newly developed variety may be tested in observation or
preliminary trial to compare it with existing varieties in a
limited number of locations to see if it is promising before
more extensive testing.

7. National, Regional or International Variety Trials
 These are traditionally conducted on research stations but in recent
decades more and more of these trials are conducted in farmers’
fields.
 Usually these are multi-location experiments and involve
experimental varieties.
 Usually the trials have a check treatment which is commonly known
and used in crop production, against which the other treatments
may be compared.
 Variety checks should be of similar type, maturity and vigour to the
experimental varieties.
 Progeny trials involve complex field designs, such as balanced
incomplete block, lattice, and alpha-lattice

8. On-farm trials
 Enable farmers to participate in the evaluation of treatments under
situations very similar to those of the farmers.
 Mother-Baby Trial (MBT) is a popular method of evaluating new
varieties under farmer conditions.
 MBT consists of two types of experiments:
 Researcher managed mother trial
 Farmer managed baby trials
 Mother trial may consist of two experiments:
 One conducted under the farmer’s typical management practices
 Second conducted with research-specified inputs

9.  The baby trials comprise sub-sets of the mother trial
and are located on many farmers’ fields
 The varieties are therefore evaluated under real
farmer’s conditions and create opportunities for
communication and interaction between all
stakeholders (farmers, breeders, extentionists and
seed companies)
On-farm trials (Cont’d)

10. Demonstrations
 Used to illustrate previously tested and approved technologies to
farmers
 Only few technologies are demonstrated in comparison with known
and commonly used technologies on relatively large, unreplicated
plots in farmers fields
 Demonstrations of the same set of technologies may be conducted
at many locations
 Farmers are invited to visit and evaluate the technologies so that
they may become familiar with them and be encouraged to adopt
appropriate options into their own farming practices

11.  The treatments, design, management, and data collected should be consistent
with the objectives.
 The experiment should be planned and conducted so that there will be a high
probability of measuring differences between treatments with an acceptable
degree of precision
 The experiment must be planned and executed to ensure that treatments effects
are estimated in an unbiased way.
 If an experiment is replicated in time and space, and if it is conducted in
environments similar to where the results will be applicable, then there is a
greater validity of the conclusions.
 There is always a degree of uncertainty as to the validity of the conclusions.
The experiment should give an estimate of the probability that the observed
results were obtained by chance alone.
Some important characteristics of a well-planned
experiment

12. Conducting variety trials
Criteria for selecting an experimental field
 In selecting an experimental field it is important to consider
the following:
Nature of the crop,
Nature of the soil
Cultural practices,
Accessibility of the site
History of the site
The slope of the land
Management of the land

13. Land preparation and fertilizer application
Conducting variety trials (cont’d)
 Land preparation involves land clearing, ploughing, harrowing,
fertilizer application and ridging.
 The field may be subdivided into smaller and manageable
units to facilitate the application of the needed quantity of
fertilizer per unit area.

14. Demarcation and layout of field
Conducting variety trials (cont’d)
Assemble all the necessary demarcation materials such as rope, tape,
ranging pole and pegs before the demarcation day.
Establish a base line using the Pythagoras theorem and make sure that
the four corners of the trial have right angles.
Ensure that ridges are uniformly spaced at the right distance apart; e.g. 75
cm apart, i.e. from the middle top of one ridge to the middle top of the next
should be 75 cm and so on.
Label all plots in the serpentive fashion and distribute planting material
accordingly.
Provide guard/border rows for the trial.
For proper demarcation and layout, the following operations
should be done:

15. 10 m
8 m
6 m
Method of establishing a right angle in the field by measuring
three sides of a triangle with the dimensions indicated
Conducting variety trials (cont’d)

16. Scheduling of the trial
Conducting variety trials (cont’d)
 Trials are designed and conducted in a particular way to meet
specific research objectives
 Ensure that all materials needed for the trial package have
been provided and orderly arranged.
 All operations should be planned and carried out at the
scheduled time to meet the objectives of the trial.
 Laying out of variety trials in the field will depend on the
plans made for the trial. For example, the person laying out
the trial must know the following:
Trial design and plot sequence (Serpentine or Cartesian)
Plot size (number of rows, number of planting holes/row, spacings)
Fertiliser application required

17. Serpentine plot numbering
20 19
11
10
1 2 3 4 5
9 8 7 6
12 13 14 15
18 17 16
Cartesian plot numbering
16 17
11
6
1 2 3 4 5
7 8 9 10
12 13 14 15
18 19 20
Trial design and plot sequence

18. Scheduling of the trial (cont’d)
The normal step-by-step procedure for laying out and
planting a variety trial is as follows (assuming the trial has
been designed and the seed packed into packets for each
plot):
Choose the most uniform area in the field
Establish a base-line (using the Pythagoras theorem)
and from this mark the corner points of the trial in a
square of rectangle fashion, taking into account the
need for border rows and the optimum layout of plots
and blocks.
Make the planting holes at the optimum plant
population using twine marked at the required spacing.

19.  The number of rows, plot length, alley ways and borders
should be established according to the design.
 Apply the basal fertiliser into the planting holes on one
side of each hole using an appropriate fertiliser cup to
give the required amount of fertiliser per hole.
 Label the plots with plot markers, if necessary. At least
mark the first plot.
 Lay out the seed packets according to the design and
field map. Note whether this is in a Serpentine or
Cartesian arrangement.
Scheduling of the trial (cont’d)

20. Conducting variety trials (cont’d)
Border rows
Each variety trial should have a number of border rows
surrounding the experiment, so that the varieties on the
edge of the experiment do not have any advantage over
the varieties in the centre of the experiment.
A minimum of two rows is required as a border
Choosing appropriate checks
Each trial should have at least one appropriate local check.
The local check is the best available variety nominated by each
trial collaborator.

21. Management of Maize Variety Trials
It is common to over-plant maize variety trials to ensure a
good stand, and then to thin the emerged plants to the
desired plant density at the 2-4 leaf stage.
Over-planting of experiments on farmers’ fields is not
advisable if it will be difficult to get to the field at the right time
for thinning.
Thinning of Maize Variety Trials
Top Dressing
Top dressing is usually done with N-fertilizers
about a week to flowering.

22. Data Collection in Maize Variety Trials
The usefulness of a maize variety trial is dependent on the type,
accuracy and precision of data collection.
The objectives of each experiment will determine the type of data
to be collected.
The most common traits used in maize are:
Grain yield
Plant and ear heights
Days to silking and anthesis
Root and stalk lodging
Disease and pest damage scores

23. Data Collection in Maize Variety Trials (cont’d)
Timing of Data Collection
 The time of collecting data depends on the kind of trait.
Flowering Data
 Observations must begin when the earliest varieties begin to shed
pollen or extrude silks, and must be conducted daily so as to make the
most accurate estimate of when each plot reaches 50% silking or
anthesis. Observations must continue until the latest flowering varieties
have been recorded.
Leaf Disease Scoring
 Observations must be timed to the epidemiology of the disease.
 If observations are made too early, records may give a false indication
of disease resistance.
 If observations are made too late, it may be difficult to differentiate
between normal leaf senescence and disease incidence.
 For most leaf diseases, scoring at mid-grain filling period is appropriate.

24. Timing of Data Collection (cont’d)
Plant Stand Counts
 These may be recorded any time after thinning, from about
the six leaf stage to harvesting.
Striga emergence counts and damage rating
 Observations are made at 8 and 10 weeks after planting.
Plant aspect
 Observations are made 2-3 weeks after mid-silking

25. Timing of Data Collection (cont’d)
Plant and Ear Heights
These are recorded 2-3 weeks after flowering
and before physiological maturity.
Lodging
 Lodged plants are recorded immediately prior to
harvest.

26. Data Collection in Maize Variety Trials (cont’d)
Other Important Trial Management Data to be Recorded
 Location (Latitude, longitude, altitude)
 Type of trial management applied (e.g., low N, optimal,
etc)
 Soil type and fertilizer applied
 Plot size (number of rows, row width, number of hills, hill
spacing and plants per hill).
 Planting date
 Weed, pest, and disease control measures applied
 Rainfall received and irrigation applied (dates and
amounts)
 Harvest date

27. Data Collection in Maize Variety Trials (cont’d)
Recording data in Field Books
 It is best to record the data directly into the field
books at time of collection.
 Avoid the practice of collecting data on rough
sheets of paper and then transferring these into
the field book at a later time.
 Any copying of data records increases the
chance of errors.
 Be on the look out for out-of line data.

28. Harvesting, shelling and trial packaging
Harvesting of trials
 The following harvest data are expected to be collected during
harvesting:
Number of plants at harvest
Number of ears harvested in each plot
The shelling percentage and the grain weight
Number of ears rotten
Cob aspect
 Conversion of grain yield to grain moisture-standardised yield is
as follows:
Yield (“12.5% grain moisture) = Yield x (100 – actual grain moisture
%) / 87.5

29. Evaluating the data
Once the data from all the trials have been collated, the
organizers analyze the data and publish the results through the
media or even at the local agricultural shows.
Participating farmers should expect to receive copies of the trial
report to learn which varieties performed best and were most
appealing to farmers.
Seed Companies and national maize programs use the results to
apply for release of varieties, and to know where to target the
sales of the varieties they produce.

30. Thank you