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« on: March 26, 2008, 11:27:04 AM »

Tissue-cultured garlic: Value adding variety

by Ma. Eloisa Hernandez
 July-September 2006
Volume 8 No. 3 


Remember the belief that garlic can drive away evil spirits?  Does it?  These white cloves are often seen in the dry section of the market and in every kitchen.  We use them to sauté our dishes, they are fried with our peanuts and served as spices and seasoning.

In the Ilocos Region and in many parts of the country, the green tops are used for pinakbet, an Ilocano delicacy.  Aside from being used as a food ingredient, garlic is used to treat wounds and cure certain ailments like toothache, skin diseases, and epilepsy. Its compounds are also believed to help prevent heart attack by preventing blood platelets from forming into blood clots.  It is a good source of vitamins and minerals.  These include calcium, potassium, phosphorus, protein, and vitamins A and C.

Garlic or “bawang” is one of the most economically important crops in the country.  Here in the Philippines, the Ilocos Region is the largest producer.  The plant produces bulb which is surrounded by sheaths and composed of thin-shelled bulblets, cloves or set, all of which are capable of forming a new plant.

Local Varieties
Ilocos White is the most common variety of garlic planted for commercial production in the country. It has purple to white scales, moderately resistant to insect pests and diseases. It has a prolonged span of shelf life, matures in 90 to 110 days after planting.

The Tan Bolters, another garlic variety, has bigger cloves than that of the Ilocos White.  This variety is not yet officially recommended for commercial production because of unconfirmed yield performance. It has good keeping quality. It matures from 105 to 120 days after planting.

Other varieties include Batanes White, Batangas White, Ilocos Pink and Nueva Ecija Pink.  These are available in the country but are not yet officially recommended for commercial production.

Garlic is planted on 5,312 hectares with an average production of 14,999 metric tons (BAS, 2004).  Farmers in the country are still practicing the conventional method of propagation which is by cloves.  This resulted to low average yield (2.82 MT/ha) due to low quality planting materials compared to other countries like Thailand, which has an average production of 10.6 MT/ha.  Farmers traditionally use their previous crop's harvest as their material for their next planting.  This practice is at high risk of transmitting diseases from one generation to the next and consequently, losing the varieties.

The Institute of Plant Breeding (IPB) developed a technology for the production of a new variety of garlic to solve pressing problems.  The Crop Science Cluster (CSC) of IPB developed a technology to produce organic, virus-free, true-to-type planting materials of garlic for distribution to farmers.  The team that worked on this is composed of Lilian F. Pateña (project leader), Gloria S. Rodulfo, Lolita M. Dolores, Roberta N. Garcia, and Jonathan L. Juanillas, together with Dr. Ramon C. Barba, academician and scientist, National Academy of Science and Technology (NAST).

On Testing
The experiments that tested the viability of the technology were divided into four aspects:  improved tissue culture protocol; genetic fidelity testing; virus-free indexing; and garlic organic farming.

Tissue culture protocol
“Start with a bulb dividing it into cloves to undergo heat therapy,” the project leader said.  Heat therapy produces clean planting materials and removes the virus.  The normal heat therapy takes two hours but producing the bulb for commercialization would require more energy and time.  “We experimented to determine if we could shorten the period.  The result showed that 30 minutes would be fine without losing anything, getting about 78-81% survival rate.  For the market, it is good enough,” Ms. Pateña explained.

This result is important in the commercialization of the technology as this step will save time and energy.

Tissue-culture is useful in mass producing garlic.  “Besides producing clean, disease-free and virus-free varieties, we also produce more,” Ms. Pateña said.

At present, the team has a total of 1,078 cultures comprising of shoot cultures and in vitro bulblets, 131 from the old collection (7 varieties, 15 accessions) and 947 from the new collection (7 varieties, 9 accessions).

Genetic-fidelity testing
Fidelity means there is no variability and the variety can be considered true-to-type.  Six enzymes were tested. These included 6-phosphogluconic acid dehy-drogenase (6-PGA), isocitric acid dehy-drogenase (IDH), shikimate dehy-drogenase (SDH), malate dehy-drogenase (MDH), peroxidase (PX), and acid phosphatase (AP).  A variant, malate dehy-drogenase pattern, was observed in tissue-cultured Tan Bolter.

“If found to be the same as the parent, then mass production can be pushed through,” Ms. Pateña explained. “Generally what gets in, is what gets out,” she added.

Virus-free indexing
Tissue-cultured and non tissue-cultured garlic planting materials were indexed for viruses using the two potyvirus antisera namely, Onion Yellow Dwarf Virus (OYDV ) and Leek Yellow Streak Virus (LYSV) by indirect enzyme linked immunosorbent assay (ELISA).

A high percentage of cultures of the six local varieties (Cagayan, Batanes, Ilocos White, Mindoro, Nueva Ecija Pink and Tan Bolter) was found to be virus-free (74-93%) while the imported “Elephant Garlic” which is comparatively cheaper had the most virus infection (41%).

“These showed that we are importing not only cheap varieties but we are also importing the diseases and viruses in the garlic,” Ms. Pateña revealed.

According to her, the project was able to show that the imported varieties of garlic are indeed virus-infected. This should caution us in importing to prevent infection of our local cultivars.

Garlic organic farming
For the past 3 years (2003-2005), organic farming was practiced to produce tissue-cultured garlic bulbs.  Four of the local varieties (Cagayan, Ilocos White, Mindoro and Tan Bolter) were produced organically.

In October to November 2006, a demo farm was put up in Ilocos Norte in cooperation with the local farmers and the provincial government.

“The methods on this technology have their unique characteristics,” Dr. Barba proudly said.  “As we mentioned the main purpose of the study is to produce vegetative planting materials that are similar to the parent material” Dr. Barba added.  It should be able to produce varieties that are the exactly the same as the traditional ones except that they are certified and clean and can be used for 3 years generation.

The major issue in garlic production is the ability to produce clean varieties.  “Knowing the garlic farmers in Ilocos, the introduction of cultured varieties is no longer a problem as organic farming is now being introduced,” Dr. Barba revealed.  As organic farming is being practiced, the use of chemical fertilizers will be totally eliminated.

The technology does not only produce garlic organically, but also virus-free planting materials. Infected varieties can be cleaned, producing clean planting materials.  The propagation rate is more than that of the conventional way.

The other benefit of the technology is, it further increases relationship with rice production.  Water retained after rice harvest can still be utilized, saving time and resources in irrigation.  The water retained in the mulch will conserve water and protects the clove.

With the many benefits of garlic to farmers and consumers, the technology of producing clean, virus-free, true-type planting materials should be given proper attention.  “Government should provide funds to support this project as it reaches a large number of beneficiaries,” echoed by the group.
This study was initially funded by Bureau of Agricultural Research for the period 1 October 2001 to 30 September 2002 and recently for 1 July 2005 to 30 June 2006.



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