Participatory approaches

Participatory Variety Trials For Rainfed Rice Cultivar Evaluation

To describe participatory varietal selection (mother trial and baby trial) and understand its need.

1. What is participatory varietal selection (PVS), and why is it needed?

Breeding and cultivar introduction programs produce and evaluate many varieties. These varieties may produce high yield in trials on the research station, but sometimes do not perform well in farmers fields, or may lack a quality trait that is important to farmers.

PVS is a simple way for breeders and agronomists to learn which varieties perform well on-farm and are preferred by farmers.

Introducing PVS into a variety development program can increase the chances that its products will be adopted. IRRI recommends that PVS procedures be included as a standard part of all rainfed rice breeding programs.

There are two main steps in the IRRI-recommended PVS system:

The “mother” trial.

The mother trial is an on-farm trial in which a set of new lines or introduced varieties is compared with local checks using farmers’ crop management practices. In this step, agronomists measure yield and other important traits. Groups of farmers are invited to visit the trial and rate the varieties using a simple technique called preference analysis (PS). The “mother” trial does not have to be a separate trial given that name. If the breeding program already conducts researcher-managed on-farm trials, demonstration trials in which data are collected, or even advanced on-station multi-location trials at several research centers, farmers can be invited to visit the trial site and perform PA.

The “baby” trial

Varieties that perform well and are preferred by farmers in the mother trial are evaluated by farmers on their own farms in baby trials. Baby trials are small trials of 2 to 5 varieties that are given directly to farmers. Researcher do not lay out these trials. They are planted and harvested by farmers. Researchers may take crop cuts to measure yield if resources permit, but farmer ratings, comments, and yield reports have been shown to be highly reliable and are the main output of the baby trial. Farmers rate the varieties in comparison to their own.

Model of Mother-baby trial

What is the difference with conventional on-farm variety testing?

In conventional breeding and testing programs, on-farm trials are conducted as the final step in a long selection process that may involve many replicated trials conducted on research stations. Researchers usually manage conventional on-farm trials. These trials are good for measuring agronomic traits, but they often do not include a step where farmers are asked their opinion about the varieties in the test.

PVS trials are managed by farmers or use the same management techniques used by farmers, and they always include a step in which farmers’ opinions are collected in a way that allows the information to be summarized as numbers or ratings, as well as in lists of farmers’ comments about the varieties. In this step, the opinions of women farmers, poor farmers, and farmers from minority ethnic and social groups are specifically sought.

Attention must be given to collect the opinion of the women farmers

2. What are the main barriers to adoption of improved rainfed rice varieties, and how does PVS overcome these barriers?

Adoption of improved rainfed rice cultivars has been limited in some systems.

Three main reasons are often suggested for this poor rate of adoption:

A. Varieties selected on research stations may not perform well under farmer management.

The problem

How does PVS help?

Variety trials conducted on the research station are often managed very differently from farmer practice. For example, researchers apply more fertilizer, achieve more complete weed and pest control, and irrigate more frequently than farmers can. High-yield varieties that perform well under these “high-input” conditions may not perform well under more stressful conditions faced by poor farmers who cannot spend much on purchased inputs or who lack the labor to completely control weeds.

PVS trials, which are conducted on-farm and under the complete management of farmers, provide information about the performance of new varieties under the real conditions faced by farmers. Traits like weed competitiveness and yield under low-fertility conditions can be assessed in PVS trials.

B. Breeders may not be aware of some of the important traits that are needed or preferred by farmers

The problem

How does PVS help?

Conventional varietal testing focuses on agronomic performance (traits like yield, duration, and disease resistance), but farmers consider many other features of a new variety when deciding whether or not to adopt it. Cooking and eating quality is a critical factor in the adoption of new varieties. Farmers may also be concerned with straw quantity, weed competitiveness, harvestability, and storability. These factors are very hard to evaluate in conventional variety testing programs, but may be strongly related to farmers’ decisions on adoption.

PVS trials include formal steps in which farmers express their opinions and preferences about varieties under evaluation. Farmer input is sought on both production and end-use traits, using tools that ensure that traits important to farmers are emphasized. This input is very useful in predicting whether or not farmers are likely to adopt a variety.

C. Farmers may not have access to information about or seed of new varieties

The problem

How does PVS help?

Many farmers in rainfed rice environments rely almost entirely on their own seed supply for planting material, and on their relatives, friends, and neighbors for new germplasm. They may be unaware of or have no access to improved varieties.

PVS trials are an inexpensive and effective way to expose farmers to new germplasm. Farmers often spontaneously adopt varieties they observe or grow on their own farms in PVS trials. In some situations, dissemination of varieties is one of the goals of PVS trials. However, the main purpose of PVS is to provide information about variety performance and acceptability. Other mechanisms, notably large-scale seed distribution schemes, are likely to lead to more rapid dissemination of farmer-preferred varieties.

3. What are "Mother trials" and how to execute them?

These are on-farm trials laid out, planted, and harvested by researchers. The Mother trial is the step after the replicated on-station trial (RYT). Mother trials are conducted using crop management typically used by farmers in the area. If farmers apply only a small amount of fertilizer, the Mother trial should receive the same amount of fertilizer.

3.1 Experimental design and number of varieties in the Mother trial

Mother trials are usually planted as unreplicated trials on at least 5 different farms. If resources permit, the trials can be replicated within each farm using a randomized complete-block design (RCBD). Mother trials can accommodate many varieties. IRRI and its collaborators have successfully managed Mother trials with as many as 50 varieties, but usually 10 to 20 varieties are included. Plot sizes of at least 1.5 m x 6 m should be used. Farmers often find it easier and more realistic if slightly larger plots are used than are normally used in on-station trials, but it is not necessary to use very large plots.

3.2 Replication within and across farms

It is very important to replicate Mother trials over several farms. Replication over farms increases the accuracy of variety means estimated from the Mother trials, and ensures that varieties are tested under a range of conditions. A minimum of 3 or 4 Mother trials is needed for reliable results, but more are desirable. If some farmers use high levels of inputs while others use low levels, then some Mother trials should be conducted under each input level.

3.3 Agronomic data collection

Researchers should collect important agronomic data from Mother trials on economically important traits and characteristics of importance to farmers. These traits should include:

Seedling vigor (for direct-seeded trials)
Flowering date
Height at maturity
Lodging rating (if any lodging occurs)
Ratings for damage by important pests or diseases (if they occur)
Maturity date
Grain yield
Straw yield

Other data on other traits may be collected if they are important to farmers or will be used in selection decisions, but researchers should avoid collecting data that will not be used. Collecting unusable data wastes time and money.

A note on measuring yield: Click here

3.4 Recording information about trial conditions and problems

It is important to collect some data about the conditions under which the trial was conducted. Information about soil conditions, water availability, previous crops, and pest and disease outbreaks can be very useful in interpreting the results of the trial.

The following information should be collected for each Mother trial:

Soil texture
Previous crop
Toposequence position (upper, middle, or lower field)
Slope (for upland trials)
Length of fallow (for upland trials)
Number of years previously cropped by rice since last burning (for upland trials)
Sowing date
Transplanting date (for lowland trials)
Amount and type of fertilizer used
Water depth and proportion of field covered by water at several times during the season
Periods of drought
Any damage to the trial by rats, birds, buffaloes, children, dogs, etc.
Serious outbreaks of pests or diseases that affected many plots in the trials

3.5 How to handle missing yield data

Sometimes a whole plot produces no yield. If the plot is lost due to animal grazing, a mistake by the researcher, premature harvest by the farmer, or other similar reason, it should be recorded as missing data. However, if it failed to produce any yield due to drought stress, poor adaptation, or other reasons related directly to varietal performance, the yield should be recorded as zero. Failure to record yields of zero can seriously bias upwards the yields of poorly-adapted varieties, leading to mistaken varietal recommendations and harm to farmers.

3.6 Preference analysis

Preference analysis (PA) is a fast and efficient way of collecting information about which varieties farmers prefer in a mother trial. The objective of a preference analysis is to rapidly and simply assess the opinions of a group of farmers regarding a set of varieties in a trial. This is done by allowing a group of farmers to “vote” for their preferred varieties during a field day by depositing paper ballots in a bag or envelope in front of the plot. After votes are tallied, the farmers are asked to discuss why they preferred the varieties receiving the most votes.

The preference analysis thus generates 2 kinds of data:

A quantitative preference score for each variety, expressed as the number of votes it received divided by the total number of votes cast
A list of characteristics farmers like about the preferred varieties

Because the activity is conducted at a specific crop stage, usually just before harvest, it is a snapshot of preference at that stage, rather than a completely reliable estimate of what farmers think about the varieties. However, preference analysis can reveal important information about traits farmers value as well as their initial impressions of new varieties.

Farmers tend to enjoy this process, which can be described to them as an “election” or a “beauty contest”. It is very simple to use, requiring no survey forms, and produces a quantitative score for each variety that is easy to analyse statistically. Farmers are not asked to rate or rank all varieties, a process they find tedious. Very importantly, this method works well with illiterate farmers, since they do not have to be able to read or write to take part.

The main weakness of preference analysis is that it is done before harvest. Farmers do not have any post-harvest data on which to base their choices and comments. Thus, it is only a tool for preliminary identification of varieties for more extensive farmer-managed evaluation.

Please click on the arrow below to see the different steps in PA

The preference index

A preference index (PI) is generated for each variety by expressing the number of votes cast for that variety as a proportion of the total number of votes cast:

PI = (No. of votes for variety)/(total votes cast)

One problem with the preference index as described above is that many varieties often receive no votes, while a few receive many. This is good for varietal selection but it can be helpful in clarifying why farmers dislike certain varieties if the truly disliked varieties are clearly differentiated from varieties that are simply mediocre. Having many varieties that have an index value of 0 also causes problems for statistical analysis- the resulting data may not be suitable for analysis with standard ANOVA techniques. Some researchers therefore also ask farmers to vote for the worst varieties, using a separate ballot. Ballots for good varieties can have a “smiling face” (☺) drawn on them; ballots for bad varieties can have frowning face. Farmers find using these separate ballots for good and bad varieties quite easy. If separate ballots for good and bad varieties are used, the index for each variety is calculated as:

PI = (no. of positive votes – no. of negative votes)/Total no. of positive and negative votes cast

An analysis of variance can be conducted on these scores for trials that are replicated over locations. In this analysis, individual locations are usually considered replicates. LSD values for the scores are calculated from the variety x location (residual) variance.

Analysis of PA data

At a single site, a chi-square test of homogeneity can be used to determine whether the preference for a line under test is significantly different than for a check variety.

If preference analyses are conducted at several locations, a combined analysis of variance over locations can be performed on the scores. Data should be presented in a 2-way table, with varieties on one axis and locations on the other. Marginal means for varieties can be presented with an LSD for the difference between varieties over locations. The LSD can be derived from the error term for the analysis of variance over locations, using a 2-way analysis of variance, in which varieties and locations are the factors, and the error term is their interaction.

Useful tips for conducting PA

At least 2 researchers are needed, 1 to guide farmers, and one to tabulated and record.
Bags and ballots should be prepared in advance
If possible, grain samples should be placed in front of the plot, so that farmers can also judge on the basis of grain size and shape.
Although the voting procedure in PA is easily conducted with large numbers of farmers, the focus-group discussion to clarify the voting results is an important part of the exercise, and is best done with a group of no more than 10-12 farmers at a time. It is usually best to conduct separate discussions with women and men. If a large group of farmers participates in the voting procedure, they should be broken up into smaller groups for the focus group discussion.

Strengths and weaknesses of PA

The PA method can work with large groups of farmers.

Its advantages include the ease of doing it with illiterate farmers, its simplicity and speed (it can easily be completed by 2 researchers with a group of 10-20 farmers evaluating 20 varieties in an hour or so), and the fact that it generates both a numerical preference rating and a descriptive list of the advantages and disadvantages of the preferred varieties.

Its main disadvantage is that, because it is done before harvest, it cannot detect preferences for post-harvest traits. Cooking and eating quality traits are not usually conveniently assessed using PA, although some programs have used the method for this purpose. It is best to include only varieties known to be of good quality in PVS trials.

Click here for an example

4. Baby trials

Mother trials allow researchers to identify a small group of varieties (3-10) that yield well under farmer management, and are chosen by farmers as desirable in the PA process. More information on varietal performance, farmer preference, and potential adoption of these varieties can be obtained in a following step called the Baby trial.

In the Baby trials, farmers are given seed samples of 1 to 5 kg (usually, 2 kg is adequate) of each of two or three of the varieties selected in the Mother trials. Farmers plant these varieties on their own farms, without researcher assistance. Researchers then visit the farms twice during the season: once to ensure that the trial was established and the varieties can be identified, and once to ask farmers to rate the varieties relative to each other and to their own variety.

Baby trials are entirely managed by the farmers

4.1 Purpose of Baby trials

Baby trials can have two main purposes:

To assess performance of varieties on a large number of farms
To help disseminate new varieties.

In general, PVS is most useful as a data collection tool. Programs for giving small amounts of seed to large numbers of farmers, without trying to collect data, are likely to be more effective in variety dissemination.

4.2 Experimental design

In a Baby trial program, the individual farm is the block. No farm should receive more than three varieties, but the trial as a whole may include four or more varieties. In this case, each farm is an incomplete block. If there are more than three varieties in the trial, varieties should be randomly assigned to farms. The three varieties per farm are referred to as a kit.

Replication levels for Baby trials need to be high. Each variety should be tested on at least 10 farms. Researchers can expect to lose at least 25% of Baby trials due to animal damage, loss of stakes, failure to plant the seed, seed mixing, etc.

4.3 Seed for Baby trials

Baby trials should be replicated across many farms, so a large quantity of seed is needed. The production or acquisition of this seed needs to be carefully planned. Seedlot quality can have a big impact on seedlot performance, especially in direct-seeded systems. If farmers are asked to compare varieties grown from high quality seed provided by the project with varieties grown from their own seed, the comparison may be biased in favor of the new varieties.

Usually, seed for wet season trials should have been produced in the previous wet season, and stored as farmers would store it. If dry season seed is used, it may be necessary to break dormancy. Assuming dormancy is successfully broken, fresh dry-season-produced seed may have better germination and vigor than wet season seed, so care must be taken when comparing the performance of new varieties and farmers’ own varieties in Baby trials.

4.4 Recruiting and identifying villages and farmers

Villages should be chosen to be representative of the target region, production system, land types, ethnic group, etc. The support of local government and extension officials, farmer groups, and local NGOs should be obtained in a planning meeting before the wet season. It may be easiest to have Baby trials in the same villages as Mother trials.

Choosing farmers to participate in the trial is quite simple:

Participating farmers should be rice growers
They should have a strong interest in participating
They should include representatives of the main ethnic and social groups in the community.

4.5 Distributing the kits

Kits should be prepared before they are handed out to farmers. In each bag of seed, at least 2 stakes with the variety name should be included, to permit varieties to be identified easily after planting. The stakes can be color-coded for easier identification.

Farmers receive kits during an organizational meeting in which the objectives and procedures of the trial are explained. During this meeting, the stakes should be shown to farmers, and it should be carefully explained to them that correct placement of the stakes in the plots is critical to the success of the trial. A list of kit numbers and the names of the varieties in each kit should be taken to the organizational meeting. The name and address of the farmer receiving each kit should be recorded.

Other socioeconomic information (ethnic group, farm size, land type, etc.) can be recorded for each participating farmer. However, as with any data, it is important to have a plan for the use of this information. Data that will not be used should not be collected. In Baby trial programs including many farmers, these data can be used to determine if different groups of farmers need different types of varieties.

4.6 Planting the Baby Trials

Farmers plant the Baby trials themselves, without the help of researchers, at the same time as they plant the rest of their crop. No special layout or plot size of the Baby trial kit is needed, but the varieties should be planted near each other to facilitate comparison. Farmers should use their normal land preparation, fertilizer rate, and seeding rate for the Baby trial. Farmers must be sure to put the identifying stakes in the plots immediately after each one is planted.

4.7 Visiting the baby trials

The first visit

After the trials have been planted, each one should be visited by researchers to ensure that it has been planted and properly staked.

The researcher should record details of the land type on which the trial is being grown, and any problems that can be foreseen (e.g., one of the varieties may be planted in an area shaded by a tree). A simple map showing the relative positions of the plots of the 3 varieties should be drawn. This can be very useful if the stakes are lost.

Click on the icon to see a sample form that can be used to conduct the baby trial 1st visit

in Word

in PDF

The second visit

Each Baby trial is visited between flowering and harvest (preferably close to harvest). The researcher should record the condition of the trial and any problems (e.g. animal damage) that can be seen. Farmers are asked to rate each variety for yield, and for their overall opinion of the variety.

The following rating scale is convenient::

1 = Much better than their current variety

2 = A little better than their current variety

3 = The same as their current variety

4 = A little worse than their current variety

5 = Much worse than their current variety

Such ratings are easily converted to numbers, and can be statistically analyzed.

For each variety, farmers are also asked if they plan to grow the variety next year. These ratings and information about the condition of the trial should be recorded on a form that clearly identifies both the farmer and the kit he or she received.

Click on the icon to see a sample form that can be used to conduct the baby trial 2nd visit

in Word

in PDF

The third visit or post-harvest meeting

After harvest, a meeting of participating farmers should be held in the community. Farmers can be asked to rate the varieties again for yield and overall preference. Ratings for eating quality can also be obtained if farmers have started to cook the rice.

A group discussion on the performance of the varieties should be held, and farmers should be asked to talk about the good and bad features of the varieties.

Click on the icon to see a sample form that can be used to conduct the baby trial 3rd visit.

in Word

in PDF

4.10 Data analysis

Analysis when all varieties are included in each baby trial

The statistical analysis of quantitative data from baby trials is very simple if all varieties are included on each farm. Variety means over trials can be calculated and presented with no adjustment. The LSD for differences among cultivars can be calculated from a standard 2-way ANOVA, with cultivars and farms as factors.

Analysis when there are more varieties than can be planted in a single baby trial

Baby trials should test no more than 3 varieties per farm. More than 3 varieties may be included in a baby trial program, but only 3 can be tested on any given farm. In this case, 3 varieties should be chosen at random for testing on each farm. This means that comparisons between varieties are partly confounded with differences in the mean yield levels among farms. If there are large yield differences among farms and replication is limited (4 replicates per variety or fewer), farm effects can obscure the value of genotypes, and least-squares means should be estimated.

However, if each variety is tested in many baby trials (10 or more), then a simple calculation of means over trials will give accurate results. In either case, the standard errors for variety means over trials, and a significance test for the effect of cultivars, can be estimated using a statistical software package that contains the restricted maximum likelihood (REML) algorithm, such as SAS, Genstat, or ASReml.. A two-factor analysis is performed, with varieties considered fixed factors and farms, random.

4.11 Village assistants

If resources permit, it is very helpful to hire a village assistant to help with farm visits and data collection. The assistant can help organize meetings and train farmers, once he or she has been trained.

The village assistant can be a literate farmer or a student who is the child of a participating farmer. A small salary (pay for one or two days work per week) should be provided to the village assistant.

4.12 Who owns the seed from the trials?

The participating farmers own the seed from the trials. They do not usually receive any other payment.

If researchers need seed for dissemination or further testing, they should purchase it from the farmer at a fair price.

Next lesson

In the last lesson of the course, we will focus on farmer participation.