Participatory Variety Selection on Sweet Potato in Sandingan and
Panglao, Bohol, Philippines
Year: 2001
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Sweet potato varieties were distributed to
farmers in Panglao and Sandingan to increase available plant
genetic resources for farmers’ evaluation and selection.
Thirty-five varieties were collected from a research institution
and distributed to farmer-partners along with descriptors’
lists. Results showed that 29 varieties survived under Sandingan
and Panglao conditions. A total of 25 varieties produced tubers.
However, these tubers were mostly small. Ten varieties had tubers
infested by weevils. Several problems were encountered during the
study that could be attributed to limited involvement of farmers
in the research and non-inclusion of local knowledge in the
research design.
A sensory evaluation was conducted after
harvesting to determine the gastronomic characteristics of eight
varieties. Four varieties were found to have good eating
qualities. Results showed that farmers have selection criteria
when evaluating gastronomic characteristics of varieties. These
were sweetness, flesh texture, water content, color and aroma.
Moreover, there are differences between farmers in terms of
selection criteria, priorities and perceptions of varieties.
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Sweet potato (Ipomea batatas) is a major crop in
non-rice and marginal areas such as Sandingan and Panglao, Bohol. It has
become the choice of many poor Filipino farmers due to its short maturity,
high-yielding capacity, adaptability to wide ecological conditions, low
input requirement, high carbohydrate content of roots and versatility
(Bernardo 1984; Bernardo 1986 and Mariscal 1987).
Studies on the sweet potato diversity in Sandingan and
Panglao made by CBDC-Bohol showed that there were few varieties grown in
these areas. Majority of the farmers in four barangays in Sandingan grow
only two varieties while farmers in three barangays in Panglao grow 10
varieties. Farmers in these areas continuously search for new varieties
with good qualities to improve production. However, very few varieties can
adapt to the marginal conditions of Sandingan and Panglao. Moreover,
farmers can not evaluate and select new varieties due to limited access to
sweet potato diversity.
This study was conducted to provide farmers with
different varieties for evaluation and selection and to facilitate farmers’
access to sweet potato diversity. Distributing new genetic materials
increases farmers' choices and increases the chance for farmers to select
new varieties (Witcombe and Joshi 1996; Witcombe et al 1996 and Joshi and
Witcombe 1996).
Description of study areas
Sandingan and Panglao are peninsulas on the west and
southwest coasts of Bohol, respectively. Sandingan is 32 km from
Tagbilaran City, the capital of Bohol while Panglao is 18 km away.
Sandingan is composed of eight barangays while Panglao is composed of 10
barangays. According to the 1990 data, Sandingan has 873 households with a
population of 4350 while Panglao has 3056 households with a population of
17004. These areas are characterized by severe heat, lack of water,
limited rain and unfavorable soil conditions, i.e. arable land is composed
of rock and soil. Despite these marginal conditions, farming is still a
major source of food and income. Farmers grow corn, yam, cassava, sweet
potato, coconut and banana.
Field performance evaluation
Thirty-five varieties were collected from the field
genebank of the Philippine Rootcrops Research Training Center (PRCRTC), a
research institution in Leyte working on development and conservation of
rootcrops. These varieties were mostly collections from different
provinces in the Philippines while some were advanced lines (or elite
lines) and recommended varieties. They were selected based on their
abundance and availability in the genebank. Passport and characterization
data were not available during collection.
The varieties were distributed to selected farmers in
two barangays in Panglao (Tawala and Bolod) and four barangays in
Sandingan (Mocpoc Sur, Calayugan Norte, Basdio and Caniga-an) on September
1996. These barangays were selected for the study since CBDC-Bohol has
established several farmer-partners in the areas. Distribution was limited
to selected farmers and selected barangays for monitoring purposes. The
distributed varieties will disseminate to neighboring farmers and
barangays through the local seed supply supply system since farmers
usually exchange and share varieties as also noted by Sperling and
Loevinsohn 1993 and Almekinders et al 1994.
Different sets of varieties were given to different
farmers. Descriptors' lists were also distributed. These forms are used in
gathering information on agronomic characteristics and field performance
of varieties (Querol 1992). Field performance evaluation was conducted
from October 1996 to January 1997. Results were as follows.
Percentage survival of sweet potato varieties
distributed in Sandingan and Panglao
|
Municipality |
Barangay |
Number of distributed varieties |
Number of varieties that survived |
% Survival |
|
Sandingan |
Mocpoc Sur |
8 |
7 |
88 |
| |
Basdio |
8 |
4 |
50 |
| |
Canigaan |
8 |
6 |
75 |
| |
Calayugan Norte |
14 |
13 |
93 |
|
Panglao |
Tawala |
11 |
10 |
91 |
| |
Bolod |
24 |
7 |
29 |
Percentage tuber production of sweet
potato varieties distributed in Sandingan and Panglao
|
Municipality |
Barangay |
Number of varieties that survived |
Number of varieties that bore tubers* |
% Tuber Production |
|
Sandingan |
Mocpoc Sur |
7 |
0 |
- |
| |
Basdio |
4 |
3 |
75 |
| |
Canigaan |
6 |
4 |
67 |
| |
Calayugan Norte |
13 |
11 |
85 |
|
Panglao |
Tawala |
10 |
8 |
80 |
| |
Bolod |
7 |
5 |
71 |
*Some of the varieties had tubers infested with weevils
(Cylas formicarius)
- Among the 35 distributed varieties, 24 survived under Sandingan
conditions while 15 survived under Panglao conditions.
- Other varieties did not survive due to severe heat and lack of rain.
These varieties may not be adapted to extremely hot and dry conditions
(as experienced by farmers in Sandingan and Panglao). However, it
could also be attributed to the quality of planting materials. The
vines were already wilted and dried up when they were distributed to
farmers.
- Majority of the varieties grown were not replicated. Thus, when a
variety dried up or wilted, samples of the same variety were no longer
available for evaluation.
- Several varieties produced tubers. However, these tubers were mostly
small. These varieties may naturally bear small tubers or may not be
adapted to farmers’ field conditions. Ten varieties had tubers
infested with weevils (Cylas formicarius) while the rest were
not infested. Those varieties that were infested were probably
late-maturing varieties (with maturity of more than the usual 3
months) or were planted much later than the normal planting time (i.e.
the farmers may have planted the vines in October since they were
distributed in late September). Either way, the varieties were left in
the field until the onset of the hot and dry season. Farmers observed
that weevils become active during this time. Those varieties that were
still in the field were eventually attacked. This was also observed by
Villamayor (n.d.) and Mariscal (1987).
- Other varieties did not produce tubers, which could be due to
non-adaptability to farmers’ field conditions. This could also be
attributed to the extreme environmental condition the sweet potatoes
were exposed to. The extreme heat and dryness prevented vegetative
growth of the sweet potato vines thus, there is limited source for the
sink.
- Stray animals ate several varieties thus, the full potentials of
these varieties were not evaluated. Since majority of the varieties
grown was not replicated, samples of the same variety were no longer
available for evaluation.
- Several varieties were not monitored during the season thus, these
varieties have no data on field survival and tuber production. This is
due to the lack of time since monitoring visits were limited to one
day only. This could also be due to non-availability of farmers during
monitoring visits. Availability of farmers was not determined and
visits were not scheduled.
- Farmers monitor new varieties. This is a normal process where
farmers observe plant growth and reactions to the environment and
compare new varieties with commonly grown varieties, as also observed
by Bellon (1996). This was not maximized and fully understood.
Monitoring and reporting schemes were not devised and planned with the
farmers. Moreover, there was a lack of venue for sharing of monitoring
observations.
- Some varieties were planted without labels and tags hence the
varieties could not be distinguished. Farmers may not be accustomed to
using labels and tags. They may have their own methods for recognizing
varieties that were not investigated. Moreover, farmers were not
consulted regarding the number of varieties they evaluate per planting
season. They were given two to four varieties for evaluation. However,
they may not be accustomed to evaluating a number of new varieties
simultaneously.
- Very little data on field performance and agronomic characteristics
were gathered during the study. Data were limited to field survival
and tuber production. This is because parameters to be gathered were
not identified prior to distribution. Moreover, farmers' parameters
and methods for evaluating new varieties were not investigated and
maximized. Data gathering schemes by farmers and staff were not
devised. Field performance could also be obtained from farmers through
interviews and discussions during monitoring visits.
- The farmer-partners did not fill-up the descriptors’ lists.
Farmers have their own methods, parameters and criteria in
characterizing varieties, which were not investigated prior to the
study.
The aforementioned problems encountered during the
study could be attributed to limited involvement of farmers in the
research. Since farmers were not involved in the planning and designing
stage, local knowledge, methods and practices were not investigated and
included in the research design. Moreover, problems in the farming systems
and resource constraints were not identified, thus, possible solutions
were not considered.
Involvement and participation of farmers in all aspects
of the research (i.e., problem identification, planning, designing,
implementation, monitoring and evaluation) ensure an even work flow and
success of the research (AGROTEC 1995; Mollel 1995; Natpracha and Stephens
1990; Reijntjes et al 1992; Simalenga 1995; Singogo 1995 and Stroud 1995).
If the components of the research design are familiar to farmers, the
study will be more manageable. Time and resources will be saved and
adoption and sustainability of the technology will be ensured. Moreover,
farmers will feel that they are part of the research, thus they will value
the study.
Sensory Evaluation
After the field performance evaluation, farmers
indicated their interest in further evaluation of the varieties that
survived and produced tubers. However, some of these varieties may have
inferior eating qualities. Farmers’ time and resources would only be
wasted if they re-evaluated such varieties in the field. Thus, a sensory
evaluation was conducted to determine the eating quality as assessed by
farmers. Gastronomic preferences differ from individual to individual and
from place to place, hence the evaluation.
Varieties that performed well in the field performance
evaluation were tested for gastronomic characteristics. This evaluation
was divided into two parts namely: preliminary and final evaluation.
Preliminary evaluation was conducted to determine varieties with good and
poor eating qualities. Those with good eating qualities were compared in
the final evaluation. Sensory evaluation was conducted in February 1997.
Preliminary Evaluation
Eight varieties and a check variety (Hinogabang, a
local variety) were prepared for the preliminary evaluation. The varieties
were divided into four sets, with each set having two test varieties and
the check variety. This is to ensure that farmers will not have difficulty
in evaluating and comparing too many varieties.
Twelve farmers participated in the activity. They were
divided into four groups wherein each group was given a set of varieties
for evaluation. Farmers tried the varieties one at a time. They were given
water to drink after tasting each variety to reduce error. After tasting
all samples, farmers determined their preferred and non-preferred
varieties.
Results showed that four varieties (namely VSP 7, PRS
408, VSP 4 and PRS 409) were preferred by farmers. These varieties were
sweet and had fine flesh texture. On the other hand, UPL SP 5, VSP 2, BPI
SP 2 and PRS 414 were not preferred since these varieties were watery and
too fibrous. These showed that farmers prefer varieties that are sweet and
have fine flesh texture.
Summary of farmers’ sensory evaluation
|
Group |
Varieties |
Characteristics |
Individual Scores1 |
Total Score2 |
Rank3 |
|
Texture |
Water Content |
Sweetness |
f
|
f
|
f
|
|
1 |
UPL SP 5 |
Too much fiber |
f
|
f
|
3+3+3 |
9 |
3 |
|
Hinogabang* |
Fine flesh texture |
f
|
Sweet |
2+1+2 |
5 |
2 |
|
VSP 7 |
|
f
|
Sweet |
1+2+1 |
4 |
1 |
|
2 |
Hinogabang* |
Fine flesh texture |
f
|
f
|
2+1+1 |
4 |
1 |
|
VSP 2 |
Too much fiber |
Watery |
f
|
3+3+3 |
9 |
3 |
|
PRS 408 |
Soft |
f
|
Sweet |
1+2+2 |
5 |
2 |
|
3 |
Hinogabang* |
f
|
f
|
f
|
2+2+2 |
6 |
2 |
|
VSP 4 |
Fine flesh texture |
f
|
Sweet |
1+1+1 |
3 |
1 |
|
BPI SP 2 |
Too much fiber |
Watery |
f
|
3+3+3 |
9 |
3 |
|
4 |
PRS 414 |
Too much fiber |
f
|
f
|
3+3+3 |
9 |
3 |
|
PRS 409 |
f
|
f
|
Sweet |
1+1+2 |
4 |
1 |
|
Hinogabang* |
Fine flesh texture |
f
|
f
|
2+2+1 |
5 |
2 |
*Locally-grown variety as check variety
1Score given by each member of the group on the variety
2Sum of individual scores
3Rank of each variety per group (based on total scores)
Varieties in bold italics were the best varieties
Final Evaluation
The best varieties in the preliminary evaluation i.e.
varieties most preferred by the participants, were tested in the final
evaluation. Four farmers participated. As in the preliminary evaluation,
each sample was tried and evaluated. Farmers also determined their most
preferred variety.
Results showed that farmers have added two selection
criteria during the final evaluation. Aside from taste, flesh texture and
water content, farmers evaluated sweet potato varieties based on color and
aroma. This suggests that when equally good varieties are compared,
farmers look for more desired characteristics to determine the best
variety. Thus, selection becomes more stringent.
Results of finalse nsory evaluation
|
Variety |
Individual Scores1 |
Total Score2 |
Rank3 |
|
Farmer 1 |
Farmer 2 |
Farmer 3 |
Farmer 4 |
|
|
VSP 7
|
2 |
4
(very little aroma) |
1
(sweet, fine flesh texture) |
4
(very little taste) |
11 |
3 |
Hinogabang
|
3 |
1
(fine flesh texture, aromatic, sweet) |
3 |
3 |
10 |
2 |
VSP 4
|
1
(color) |
2 |
2 |
2 |
7 |
1 |
PRS 409
|
4
(watery) |
3 |
4
(very little taste) |
1
(sweet) |
12 |
4 |
1Score given by each farmer on the variety
2Sum of individual scores
3Rank of each variety (based on total scores)
Variety in bold italics was the best variety
The study also showed differences between farmers when
evaluating varieties. Farmers differed in their criteria and priorities in
determining the best variety among equally good varieties. One farmer
chose VSP 4 based on its color; another chose Hinogabang based on its
flesh texture, aroma and taste; another chose VSP 7 based on its taste and
flesh texture and another chose PRS 409 based on its taste. Farmers also
differed in their perception of the varieties. For instance, PRS 409 for
two farmers was watery and had very little taste while it was sweet for
another. These differences are important bases for accessing and
distributing different kinds/varieties of sweet potato. These differences
must be recognized especially in varietal improvement, development,
introduction and selection activities.
Farmers’ Preferred Characteristics
After the sensory evaluation, a workshop was held to
determine the agronomic and gastronomic characteristics most important to
farmers. Results showed that farmers prefer varieties that are
early-maturing and adapted to their marginal conditions, with fine flesh
texture, aromatic and yellow flesh. Yield is also important but it is only
secondary (yield is measured in terms of tuber size, tuber weight and
number of tubers per plant). Sweet potato is mainly for home consumption,
hence, taste and gastronomic appeal, early maturity and adaptability are
more important than high yield. In the past, farmers had varieties that
had good yield but did not taste good. These characteristics could be used
as basis for succeeding distribution of varieties or re-trials.
When performing participatory varietal selection, the
following may be considered:
- Ensure farmer participation and involvement at all stages of
varietal selection from diagnosis, to planning, designing,
implementation, monitoring up to evaluation.
- Investigate local knowledge in evaluating new varieties and local
knowledge of field conditions prior to the study. Incorporate local
knowledge in the research design.
- Ensure that the research is designed through the collaboration of
farmers and staff. Devise monitoring, characterization and reporting
schemes with farmers to systematize the activities. These schemes must
be based on farmers' local knowledge and practices.
- Ask farmers for their preferred characteristics prior to
distribution. Use these characteristics as basis for acquisition of
materials for distribution.
- Pre-screen varieties based on farmers’ preferred characteristics
and farmers’ field conditions. Pre-screening narrows down the
varieties to those that can adapt to farmers’ conditions and suit
their needs.
- Handle and transport planting materials (vines) properly to avoid
wilting and drying. There are several methods that can be used to
lengthen viability of the vines. Either soak the cut ends of the vines
in water, remove several leaves from the vines or wrap the cut ends in
moist newspaper.
- Characterize the different varieties prior to distribution. Take
photographs of the vines, leaves and tubers (if there are any). These
will be very useful references in the future.
- Replicate varieties between farmers’ fields.
- Extend monitoring visits to ensure that all farmers are visited.
Schedule monitoring visits depending on the availability of farmers.
- Ask farmers to draw the field lay-out so that it would be easier to
identify which varieties are included in the study.
- Include evaluation of field performance and agronomic
characteristics during sensory evaluation to facilitate sharing of
farmers’ observations. Evaluate using participatory methods to make
the activity more interesting and to ensure participation of all
farmers.
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