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Pro Biodiversidad de los Andes |
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Technology
available to reinforce on-farm conservation of traditional Andean potato
cultivars
Zósimo Huamán
Abstract There is an on going process
of genetic erosion of Andean potato cultivars. Therefore, it is important
to establish ways to reinforce the on-farm conservation of these genetic
resources with genetic materials and technological packages to increase
productivity that are available at CIP.
Among the most important options are first, virus eradication of
traditional potato cultivars as there is a very high incidence of virus
infection in potato fields in the Andes, which cause high yield losses.
Second, the repatriation of virus free clonal materials that are available
in the genebank at CIP back to farmers. Most of this germplasm was
collected throughout Latin America several decades ago and could be used
to restore the diversity lost in situ. Third, the transfer of costless technologies to increase
potato productivity to farmers who are conserving traditional potato
cultivars. Among these technologies are the integrated pest management for
factors that cause extensive tuber damage in Andean farmer’s fields; the
use of simple and cheap diffuse light stores for tuber-seed, and the
storage of ware potatoes in rustic storage boxes that reduce losses caused
by tuber sprouting and rotting, and extend the period of time for selling
or consuming stored potatoes. Fourth, the promotion of Andean potatoes in
new markets, especially in industrialized countries whose people are used
to pay higher prices for organically produced food with exotic appearance
used in gourmet cooking. Farmers will continue growing ancient potato
cultivars if there is a market for them. Fifth, making more widely
available to Andean farmers the knowledge gained at CIP
on the identification of desirable traits in traditional potato
cultivars.
It
is widely accepted that there is an ongoing process of genetic erosion of
the diversity of potato cultivars selected by Andean farmers (Brush, 1986;
Hobbelink, 1984; Huamán, 1988; Ochoa, 1975; Zimmerer K. S. 1992). The
main factors for this loss of genetic diversity are:
a.
The replacement of ancient traditional cultivars by modern bred
varieties with higher yield potential and wider commercialization in the
urban markets.
b.
The gradual extinction of traditional cultivars due to heavy
infection with viruses and the increasing pressure caused by pests and
diseases of nearby commercial fields with potato varieties of relative
genetic uniformity.
c.
The increasing reduction of the area cultivated with traditional
potato cultivars due to the lack of opportunities in urban markets and the
migration of rural population to the large cities. Traditional potato
cultivars are increasingly isolated to small plots in micro-centers of
genetic diversity, and their production is generally restricted to home
consumption.
d.
The losses caused by frost, drought and hailstorms that are
becoming more frequent because of the global warming. Therefore, it is important to
establish ways to reinforce the on-farm conservation of ancient potato
cultivars with genetic materials that are available in the ex situ genebank conserved in trust at the International Potato Center (CIP) and modern
technological packages to increase productivity (Huaman, 1994). This
complementation between in situ and
ex situ conservation will undoubtedly contribute to the long term
and sustainable conservation of these valuable genetic resources. Among
the most important technology available at CIP to reinforce on-farm
conservation of traditional potato cultivars are the following: 1.
Virus
eradication of traditional Andean
potato cultivars. There
is a very high incidence of the potato viruses PVX, PVS, APMV, APLV, PLRV,
and PVY in potato fields with traditional potato cultivars in the
highlands of Peru (Bertschinger et al., 1990). Virus diseases have been
documented to cause up to 80% loss in yield (International Potato Center,
1984). Serological tests for the six most common potato viruses made at
CIP on tuber sprouts of 2905 traditional potato cultivars showed that
about 95% of them were infected with one to six viruses (International
Potato Center, 1995). Similarly high levels of virus infection were
reported in the Chilean potato collection held at the Universidad Austral
de Chile (Theoduloz et al., 1992). This shows quite clearly that virus
infection is one of the most serious factors for genetic erosion in
traditional potato cultivars conserved both in
situ and ex situ. Therefore,
the greatest contribution towards the survival of cultivated potato
genetic resources is the eradication of viruses from traditional
cultivars. CIP has reported the availability of the technology to clean of
viruses from about 600 cultivars per year and the initiation of a
systematic program of virus eradication from the cultivars held in trust
(International Potato Center, 1995; Huaman, 1998). At this time, CIP has
available virus free materials of almost half of the collection of
traditional potato cultivars from Latin America. 2.
Restoration
of genetic materials lost in farmers’ fields. It
is rather fortunate that the ex
situ genebank conserved
at CIP, still maintain, by vegetative propagation, thousands of ancient
potato cultivars that were collected throughout Latin America several
decades ago (Huaman et al., 1997). Although this collection has been used
in very few cases to restore some potato cultivars lost in farmer fields
(Huaman and Schmiediche, 1991), more systematic ways to repatriate these
genetic materials back to the farmers who have been conserving them in
situ for generations should be implemented. A
pilot project to find ways to repatriate in a large scale virus free
stocks of traditional potato cultivars back to farmers’ fields was
initiated in 1998. The approach tried was to multiply virus free plantlets
of Peruvian traditional potato cultivars, conserved as in vitro cultures
at CIP, in a quarantine screenhouse at the experiment station located in
Huancayo, Peru (3,200 m elevation). The tubers obtained were further
multiplied in a plot rented in an Andean community, located in a
micro-center of potato diversity. Because of the limited number of tubers
of each cultivar is available in the ex
situ genebank, there was a need to establish an efficient way to
transfer a few tubers to farmers in different communities for further
multiplication and distribution. Tubers of potato cultivars collected in
the Department of Huancavelica were provided to farmers participating in
communal activities in San Jose de Aymara (District of Pazos, Province
Tayacaja, Department Huancavelica, Peru), located at 3,900 m a.s.l., to
initiate a pilot project for the development of a Community Seed Bank (CSB).
Aymara is located in a micro-center of genetic diversity of Andean potato
cultivars, where many farmers plant parcels with mixtures of traditional
cultivars and are organized in groups that participate in the “Seed
Fairs” in Central Peru. This community is also a source of tuber-seed
supply. The
experience obtained showed clearly that farmers are very grateful for
getting back virus free
tuber-seeds of their traditional cultivars. Farmers indicated that several
of the cultivars returned were considered lost in farmer fields because
they could no longer find them in other nearby or distant communities
where they traditionally go to recuperate or increase their potato
diversity. Another well noticed fact by farmers is that the tuber-seed
received from the ex situ
genebank produce plants that grow very well, look very healthy and yield
considerably more than their own virus infected plants. This is true not
only for the number of tubers produced but also for their size. We
observed at least 20% in yield increase when healthy tuber seed is
compared with those from
virus infected plants. In
Peru, eleven CSB’s have already been organized in the Departments of
Huancavelica, Junin, Huanuco, Apurimac and Lima. Non Governmental
Organizations could continue this effort at relatively low cost. The goal
should be to have a network of CSB’s with at least two supervised
CSB’s per Department. Experience has shown that once a CSB is
established, farmers are willing to share sets of the materials they have
increased with other neighboring communities. 3.
Transfer
of technology to increase potato productivity in the field of subsistence
farmers CIP
and other research institutions have developed a number of technologies to
increase potato productivity in developing countries. Among those that
should be transferred to farmers conserving traditional potato cultivars
are the low cost technology for integrated pest management, tuber-seed
storage, and ware potato storage. Alcazar
and Cisneros (2000) indicated that Andean potato weevils (Premnotrypes spp) are the most serious potato pests at high
altitudes in the Andes. The damage of tubers at harvest can be more than
50% on subsistence farms where normally no control measures are taken. In
the past, the damage of this insect was more or less negligible when
Andean farmers widely followed the practice of growing potatoes in the
same field at intervals of 5-7 years, when they maintained considerable
distances between their potato fields, and more importantly, when they
grew many different potato cultivars in the same field. The increased
predominance of potato plots with very few commercial varieties in most of
the potato growing areas, including the most remote villages, has
drastically increased the levels of tuber damage caused by pests and
diseases . Although, the use of highly toxic insecticides in commercial
fields reduces tuber damage caused by the Andean weevil up to 15-30%, this
treatment is unaffordable by poor farmers and undesirable in small plots
where traditional potato cultivars are cultivated. Alcazar and Cisneros
(1997) reported that the integrated control of this insect in Aymara
reduced tuber damage from about 40% to 15%. However, in the Communal Seed
Bank, the average tuber damage was below 5% in the most susceptible
cultivars because it was planted in a community plot, in which no potatoes
had been grown for 5 years and where integrated weevil control measures
were applied. In general, farmers that participated in the CSB’s got
on-the-job-training in integrated pest management practices. CIP should
continue the dissemination of this technology to Andean farmers as well as
the one to control potato tuber moth Phthorimaea
operculella and Symmestrichema
tangolias (Palacios
and Cisneros, 1997) in areas where these insects cause great losses in
Andean farmers’ fields. Other
simple and cheap technologies developed at CIP that have shown good
results are the use of diffuse light stores for tuber-seeds (Booth, 1984)
and the conservation of ware potatoes in rustic storage boxes (Túpac
Yupanqui, 1997) that reduce yield losses due to tuber sprouting and
rotting, and extend the period of time to sell or consume stored potatoes
of traditional cultivars. McGee et al. (1988) reported that prototype
rustic diffuse daylight stores for tuber seed developed at Huancayo, Peru
resulted in an increase in yield of the subsequent crop by about 20% and
in more rapid emergence as compared with seed stored in darkness. Andean
farmers traditionally store potato seeds in the dark, which produces very
long sprouts that have to be removed at planting. Desprouting delays
emergence and senescence of the crop, and in most cases reduces yield
(McGee et al., 1988). During the development of the CSB’s, opening a
space in the roof and covering it with a transparent fiberglass sheet in
the room designated by the community for seed storage implemented this
technology. At planting time, farmers noticed that there was no need to
desprout their tubers before planting, which saved some labor. They also
noticed the increased yield of tuber seed stored in diffused light when
compared with those stored in the dark. Most
subsistence farmers store native and commercial potatoes for their
home-consumption and as a cash crop after harvest. The relative low
temperatures in the Andes during the months after harvest are an important
factor for good storage. Total losses of Andean tubers during storage
ranges between 25% and 58%, depending on the crop and on the quality of
the tubers at the time of storage. The most important factors causing
these losses are the infection with rot producing pathogens, insect
infestation, mechanical damage and the sprouting of the tubers. Túpac
Yupanqui (1997) reported reduction of these losses to about half by a
careful selection of the tubers to be stored; the use of rustic store
boxes designed to provide good ventilation, and the application of a
sprout inhibitor. The introduction of this technology in the Community
Seed Bank at Aymara has created great interest among farmers. In 2000,
they built the store facility for ware potatoes, following the design
recommended by Tupac Yupanqui and stored about 1,000 kg each of
traditional and improved potatoes. They monitored the tuber appearance as
well as the market prices. After six months in storage, the tubers were in
good condition, without sprouts and weight losses averaged 3 % of the
initial weight. Most important, at harvest time, the market prices were
very low, and after six months farmers got in between three and four times
of those prices. The extra cash received, allowed the farmers to buy basic
supplies for their next planting. 4.
Promoting
a wider consumption of traditional Andean potato cultivars The
best way to secure sustainability in on-farm conservation of traditional
potato cultivars is by means of promoting a wider consumption of these
potatoes in urban markets. In Peru, the cultivars “Papa Amarilla” and
“Puca Huayro” are widely recognized as potatoes of great culinary
quality, and their prices are generally three to four times of those of
any bred commercial variety. In recent years the traditional cultivars
“Puca Camotillo”, “Peruanita”, “Ishcopuro” and
“Huamantanga” have been successfully introduced in the Lima market.
Therefore, we conducted an evaluation of the culinary quality of 133
cultivars of samples obtained from the CSB’s at Aymara and Collpatambo (Huancavelica,
Peru). Their dry matter content ranged from 19 to 32%, and 31 cultivars
were selected with culinary quality (texture and flavour) similar or
better than those of “Papa Amarilla” and “Puca Huayro”. These 31
cultivars are being multiplied at the CSB to start an effort to promote
them in the urban markets. In addition, since the Peruvian government has
invested in studies to export “Papa Amarilla” to the markets in the
USA and Japan (Fano et al., 1998), an effort was made to determine the
feasibility of pre-cooking and freezing tubers of all traditional potato
cultivars accepted in the Lima market to be used for fast microwave
cooking. Frozen potatoes could overcome the customs barrier to the export
of traditional potato cultivars from the Andes. We found no significant
differences in the texture, flavor, flesh color, and tuber appearance of
all cultivars tested after cooking them fresh or as frozen tubers. These
tests were conducted monthly for up to six months. Most cultivars are
cooked after 6-8 minutes in the microwave oven after thawing for about 20
minutes. 5.
Use
of evaluation data obtained at the ex
situ genebank at CIP
The potato database at CIP comprises more than 46,000 evaluations
of reactions of traditional potato cultivars to biotic and abiotic
stresses as well as of other desirable traits (Huaman et al., 2000). This
database shows hundreds of traditional cultivars with resistance to one or
more diseases, pests, environmental stresses, or other desirable factors
(Huaman, 1987). Therefore, CIP should make more widely available those
potato cultivars with resistances to stresses that affect Andean farmers
to increase food supply and restore or increase genetic diversity lost
through the years. As indicated before, the Andean potato weevil is one of
the most important causes for genetic erosion of Andean tuber crops.
However, traditional potato cultivars have different levels of tolerance
to this pest. Alcázar
and Cisneros (1991) reported some traditional cultivars with antibiosis
resistance to Premnotrypes
suturicallus because they showed a reduced larvae survival rate in the
tubers. They also reported a negative correlation between the tuber damage
and the depth of tuberization. The CIP potato database also shows that
from 2728 accessions evaluated against
the Andean potato weevil 96 showed various levels of resistance to P. suturicallus, P.
vorax, or P. latithorax. Seven of these cultivars combine resistance to the
three weevil species. (Huaman et al., 1997). Because this potato pest is
not of global importance, CIP has not conducted any breeding effort to
develop varieties resistant to the Andean weevil. However, it is important
to use these known sources of resistance to Andean weevil in order to complement
other cultural practices of integrated control to reduce the tuber damage
caused by these insects. Five
traditional potato cultivars with resistance to Andean potato weevil were
selected from the evaluation potato database at CIP. Seedlings were
obtained from open pollinated and selfed seeds tested against seed
transmitted viruses and viroids and transplanted in a potato field at
Aymara where severe damage caused by Andean potato weevils had been
reported. These plants were harvested very late to favour insect damage.
Genotypes with severe weevil damage were discarded. Farmers selected a
total of 186 clones without visual damage in the tubers and planted them
in the next season in a highly
infested field, using 10 hill plots together with highly
susceptible cultivars. Twenty-five out of the 186 clones tested continued
showing some weevil tolerance and had good yield. The tuber damage ranged
from 25 to 50%. Other clones and traditional cultivars used as controls
had 100% of their tubers damaged. Farmers recommended using these weevil
tolerant clones as a protecting border of the Communal Seed Bank plots. Similar farmer participatory breeding efforts with
traditional potato cultivars could take place to reduce tuber damage in
areas where Spongospora powdery
scab, Synchytrium wart, etc. are
causing genetic erosion. There are many traditional potato cultivars in
the CIP database with resistance to these diseases. However, this
important information does not reach Andean farmers. Benefits to farmers and in situ conservation
The
experience obtained for using Communal Seed Banks as the link between ex
situ and in situ conservation of traditional Andean potato cultivars has been
quite encouraging. The initial farmer skepticism that outsiders always
take advantage of them had to be overcome by assuring them that all tubers
produced in the CSB were their property and were under their total
control. In addition, the strategy of initiating the formation of the CSB
with tuber samples free of viruses of hundreds of cultivars being donated
by the ex situ genebank normally
opens the door to very fruitful collaboration. This experience shows the
great benefit that CIP could contribute to on-farm conservation of potato
diversity by repatriating the about 1000 virus free potato cultivars from
16 Departments of Peru that are already available for distribution. We
found strong evidence that the genetic materials that have been stored ex
situ for decades comprise many cultivars that are now lost or very
difficult to recover in situ. In
addition, the repatriation at a wider scale of these virus free genetic
materials back to Andean farmers will benefit them directly because there
is a considerable increase in their yield potential, producing more food
to eat or to trade. In addition, the replacement of virus infected
tuber-seeds of ancient cultivars with virus free stocks will undoubtedly
extend their chances for survival in farmers’ fields.
Farmers
are eager to adopt new technologies such as integrated pest management,
rustic diffuse light storage and low cost ware potato storage that demand
very little economic investment and most important, increase potato
productivity. They are willing to contribute with all the labor needed to
apply these technologies because they are convinced that there will be an
increase in the availability of more food for home consumption and a
surplus that could be used to get a higher income when sold in the
markets. The
sustainability of long-term conservation of traditional potato cultivars
through a network of Communal Seed Banks or any other approach to promote
their on-farm conservation will undoubtedly depend on economic incentives.
These incentives should not depend on isolated gifts or short-term
economic donations but should be based on market opportunities. Farmers
will continue growing ancient potato cultivars if there is a market for
those potatoes. However, to prevent that this business is not taken over
by large farmers linked to transnational companies, there is a need to
create a system for a national certification of origin of this traditional
potato production. The requirement should be that these traditional
potatoes are grown at high elevations, under organic conditions, and by
farmers located in the micro-centers of potato diversity who maintain
collections of existing traditional cultivars in the area. The success of
this approach will largely depend on opening new markets for these
traditional potato cultivars, especially in industrialized countries whose
people are used to pay higher prices for food used in gourmet cooking,
organically produced, and with exotic appearance. The implementation of
this type of trade will be a clear example of the equitable sharing of the
benefits of using potato genetic resources. The poor farmers of the Andes
could continue conserving these valuable resources for all mankind with
the economic incentive created in the markets of the industrialized
countries. Acknowledgement To all farmers who participated in the development of 11 Communal Seed
Banks of traditional potato cultivars in five Departments in central Peru,
and to Ing. René Gomez, my
former research assistant at the International Potato Center. References
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