Updates on Sweet Potatoes
The Philippine Root Crop Research and Training Center(PhilRootcrops for short) has gone a long way in improving the productivity as well as the taste and other qualities of the lowly camote or sweet potato.
Long before the research and training center was established in 1977. farmers used to harvest an average of eight tons of roots per hectare from their favorite varieties. Today, the yield has increased to an average of 12 to 15 tons per hectare. Of course, there are varieties that give much higher yields like VSPI which gives an average of 21.90 tons per hectare, thanks to the researchers.
In the beginning, the target of the researchers was to produce hybrids that will produce high yields, says Dr. Jose Bacusmo, the president of Visayas State University (VSU), who has been involved in the sweet potato research program from the beginning up to now. He still acts as the project leader of the research program although other staff acts as head of the center. The present head is Dr. Julieta Roa.
What’s good about sweet potato is that it freely bears flowers so that it is easy for the plant breeders to cross different strains to produce hybrids. The plant breeders try to incorporate in the hybrids the desirable characteristics such as high yield as well as taste, suitability for processing and others. At present PhilRootcrops boasts of 946 accessions from all over the Philippines and abroad which the researchers can use for breeding.
High yield, of course, is just one desirable characteristic and if a high-yielder has some undesirable traits, it will be eventually discarded. Just like VSPI, the first hybrid released by PhilRootcrops in 1983. It is high-yielding all right, but then it is susceptible to pests and diseases. Worst of all, it has a low dry matter content of 26.6 percent. Roots with low dry matter content are not as tasty as those with higher content. says Dr. Julie Tan, head of the postharvest division of the center. Those with high dry matter content are highly Suitable for ‘camote-cue’ because the flesh docs not easily break.
One hybrid produced by PhilRootcrops that has had a very big impact is VSP6 released in 1988. In the early 1990s, the camote plantings in Central ,Luzon, particularly in Tarlac and Pangasinan, were wiped out by the mottle virus disease, according to Dr. Bacusmo. It was VSP6 that came to their rescue. Up to now, VSP6 is the main variety being planted commercially in many parts of Luzon. Besides giving an average yield of 21.02 tons per hectare, it has a high dry matter content of 32.90 percent. It has excellent taste as boiled camote.
Another significant hybrid released in 2002 is what is now known as NSIC SP25 or the LSU Purple. It has a marbled purple flesh which is desirable because it is said to be high in anthocyanin. This means it contains a lot of antioxidants which is good for the health.
Dr. Julie Tan says that among the various varieties released for commercial production, LSU Purple has about the highest dry matter content of 36 percent, hence it is very tasty when boiled. It is sweet because it has the highest sugar content of 4.07 percent compared to most varieties which only have 2 to3 percent. ‘
One planter from Negros Occidental who saw the potential of LSU Purple ordered at one time 50,000 cuttings for planting. It was also extensively planted in Bicol after a recent calamity that devastated the region. That’s because a rootcrop like camote is the ideal food crop to grow where typhoons arc prevalent. It also matures in a relatively short period of 105 to 120 days after planting.
Camote roots are an important supplement to rice when the cereal is in short supply. In Cebu, they practice what they call `saksak.’ This is when rice or white corn is scarce. What they do is to add pared sliced sweet potato to the rice or white corn that they cook.
LSU Purple is also Dr. Julie Tan’s favorite for processing: She is in the process of perfecting a sweet dessert wine with low alcohol content. It will be more of an energy drink, according to her. She exhibited samples of her camote wine during the agri-fair and garden show in connection with the recent celebration of VSU’s 85th anniversary. Those who have tasted samples of it say it is sweet and refreshing.
Of course, camote varieties with low dry matter content also have their own uses. Just like an accession called RC2000. This has low dry matter and low starch contents which make it ideal for processing. Dr. Tan has produced a pickled camote which was a bestseller at P40 per small bottle during the garden show. RC2000 makes an attractive ‘atsara’ because it has intense orange color similar to that of carrots. Dr. Tan has developed a process in producing crunchy camote pickles. Another product of Dr. Tan is a sweet camote bar.
Most of the 32 varieties released for commercial production are products of the PhilRootcrops. A number, however, were released by UP Los Banos, Bureau of Plant Industry and the Northern Philippine Root Crop Research and Training Center based at the Benguet State University in La Trinidad.
Meanwhile, research at PhilRootcrops continues. Enrique Abogadie who does most of the breeding and propagation says that they are producing about 60,000 seeds of different crosses a year. Only 20,000 of these, however, are grown and observed for their desirable or undesirable characteristics. Out of the 20,000 seedlings, only 5 percent or 4,000 plants will be further observed for their performance. When one proves to be outstanding, it will be endorsed to the National Seed Industry Council for certification.
Some of the researches also focus on the control or prevention of pests and diseases. One of the most common problems is the infestation of the sweet potato weevil which renders the roots inedible when the infestation is serious. One prevention technique is to keep the soil moist so that there will be no cracks in the soil for the weevil to reach the storage roots of the plants. The weevil lays its eggs on the roots rendering them unmarketable after the eggs hatch.
If you want to see the biggest collection of camote varieties, visit Visayas State University in Baybay, Leyte. You will not only see camote but also other rootcrops like gabi or taro, ubi, cassava. arrowroot, singkamas and even pungapong or amorphophallus.
By Zac B. Sarian