New research finds ways to extend seasonal production of purple yam

MANILA, Philippines - A government-funded research program carried out at the Visayas State University is exploring new techniques to increase the production of purple yam, a high value crop used in various processed products.

Purple yam, locally known as ube, is used in various food products whether served fresh or processed. It is also used for flavoring in ice creams, baked goods and drinks.

“At present, there is a high market demand for it whether domestic or for export. However, the production of yam is very seasonal. You can produce it once a year,” said Villaluz Acedo, a professor at the Philippine Root Crops Research and Training Center (PhilRootcrops) of the Visayas State University (VSU).

Data from the Bureau of Agricultural Statistics (BAS) showed that purple yam production has significantly decreased from 30,074 metric tons in 2006 to 15,799 metric tons in 2012.

This is attributed to the highly seasonal nature of production due to tuber dormancy. Purple yam tubers cannot germinate immediately after harvest because these undergo a dormancy period of about three to four months after harvest.

Purple yams are traditionally planted in June and harvested in December. With traditional planting, farmers usually reserve 20- 40 percent of their harvest to be used as planting materials for the next season, resulting to less volume in the supply chain.

To increase the production and availability of purple yam tubers as planting materials, VSU initiated a project titled “Improvement of Yam Production System through Tissue Culture Derived Plantlets and Microtubers and Breaking Tuber Dormancy for Continuous Production of Planting Materials.”

The study is funded through a research grant from the High Value Crops Development Program (HVCDP) of the Department of Agriculture and the Bureau of Agricultural Research (BAR).

The research project aims to increase yam production in the country through mass production of viable plantlets through tissue culture and breaking tuber dormancy.

“With the tissue culture protocol that we have developed earlier, we can produce large volume of planting materials and make them available any time of the year. The protocol can produce plantlets in two weeks ready for potting out and subsequent hardening prior to planting in the field. We can also remove the disease-causing microorganisms which results in clean planting materials,” said Acedo.

Recent commercial planting trials by farmers in Davao and  General Santos showed that tissue-cultured plantlets have more promising yields of 1.5 kilograms to two kilograms per plant, higher than traditional planting materials.

By breaking the dormancy of purple yam tubers, production could be spread out throughout the year instead of the traditional growing season alone.

“With the breaking of tuber dormancy, yam can be planted anytime of the year. Thus, production can be programmed depending on the market demand,” said Acedo.

Trials showed an 80 to 100 percent germination rate in tubers after using the treatments.

“Years of experiments conducted by our scientists and researchers resulting in such technological developments are essential in boosting production and productivity in the agriculture sector. As the project continues to progress and provide promising results, a bright future is seen for the purple yam industry,” said Acedo.