BAR TODAY || Official Quarterly Publication of the Bureau of Agricultural Research

Virus-free garlic is a sure winner
by Junelyn S.de la Rosa

October-December 2003
Volume 5 No. 4

Finally, there is good news for the literally ailing garlic (Allium sativum L.) industry. Scientists have developed a new technology that can produce virus-free planting materials of garlic using an improved technique of shoot tip-meristem culture.

The scientists say the technology can reduce the high incidence of viruses and diseases in garlic such as bulb rot, downy mildew, Cercospora leaf spot, purple blotch, tangle-top disease, and nematodes and increase the crop's very low yield of 2.78t/ha, compared to that of other countries such as Thailand at 10.6t/ha.

The technology consists of pre-treatment methods and tissue culture to produce safe planting materials, virus indexing to ensure virus-free planting materials and field planting to increase the number of planting materials (cloves/bulbs). It was developed by scientists from the Institute of Plant Breeding (IPB) at the University of the Philippines at Los Baños (UPLB), and the Asian Vegetable Research and Development Center (AVRDC) with support from the Bureau of Agricultural Research of the Department of Agriculture (DA-BAR).

Before conducting the in vitro culture, the cloves are separated and cleaned using detergent and water and pre-treated by storing them in a refrigerator (5oC) or at room temperature for 1-4 weeks then putting them in a water bath at 50oC for 2 hours (thermotherapy). Cold pre-treatment and thermotherapy have been found effective in eliminating the viruses that are not destroyed during tissue culture.

Pre-treated cloves are sterilized for 15-20 minutes using commercial bleach and a drop of Tween 20. After 1 to 1.5 months, multiple shoots are divided into single shoots. The shoots are then checked for viruses using Enzyme Linked Immunosorbent Assay (ELISA). Only virus-free shoots are cultured and transplanted to a potting media in a greenhouse for 3-4 weeks after which they are transplanted to the field to produce the first generation (G1) bulbs. For the next season, the farmers can use the G1 bulbs to produce the next batch of planting materials. The cycle can be repeated up to the 4th generation bulbs after which new bulblets from tissue culture need to be multiplied again.

Using this technology, the farmers can have a continuous supply of healthy and safe planting materials. After 3-4 years of recycling the bulbs in the field, the 3rd or 4th generation bulbs can be easily replaced with new virus-free planting materials. Also, using vigorous planting materials, farmers can harvest more and sell healthier and better-looking garlic.

Finally, the technology is also good news to the millions of consumers who are aware of the health benefits from garlic such as its ability to reduce bad cholesterol, increase lipoproteins or good cholesterol and lower blood pressure. Soon, we can all look forward to having a healthy clove of garlic a day to keep the doctor away.

Source: Technology for production of certified virus-free garlic (Allium sativum L) planting materials by Lilian Pateña, Lolita Dolores, Alice Bariring, Ramon Barba of the Institute of Plant Breeding, College of Agriculture (IPB-CA), University of the Philippines Los Baños (UPLB); Erdharg Barg of BBA, Germany and Sylvia Green of the Asian Vegetable Research and Development Center (AVRDC), Shanhua, Taiwan, Republic of China