(Plant breeder Dr. Antonio Alfonso uses modern biotechnology in developing new rice plant variety. Photo by Elmo Roque)
(First of two parts)
SCIENCE CITY OF MUÑOZ – Tiny, as the untrained eyes cannot detect it – that’s the embryo of the rice seed. Yet, it is aptly ascribed as being synonymous with human life, for, according to a national social scientist, “rice is life”.
Ensconced almost at the tip of the grain, nourished by a storehouse of starch, sugar, protein and fats, and protected by a hull, this embryo develops into shoots, roots and later tillers when vouchsafed with the favorable conditions for its growth and development – water, sunlight, air, and nutrients.
Discovered by anthropologists for use more than 4,000 years ago in China, the rice seeds are both alike and different – alike in basic parts but different in their types with very important traits.
The traits, undoubtedly, compel its continuous alterations, development and adaptions and adoption for varied ecosystems and the worrisome climate change.
Otherwise, if it is not done, disaster awaits the human kind.
“There are thousands upon thousands of commercial rice varieties in the word today that were developed by modern plant breeders,” said Dr. Antonio Alfonso, formerly head of the plant breeding and biotechnology division of the Philippine Rice Research Institute.
“They are in addition to the already existing traditional and heirloom varieties that were the products of continuous selection and planting by our forefathers”, added the former Ten Outstanding Young Men Awardee and a Young Scientists Award recipient who is now with a multinational company working in rice breeding and promotion in the country.
But the best varieties in one locality, Alfonso noted, do not necessarily perform well as in another. This is because there are many factors that affect rice cultivation, which include physical (rainfall, terrain, temperature, altitude, among others), biological (the prevalent insect pests and diseases in the area), and cultural (the way people grow rice).
In some cases, varietal decline is caused by changes in the genetic purity of the variety due to repeated plantings. The other reason is on account of insect pest and diseases that have changed – such that more destructive types emerge and severe infliction of damages on previously resistant varieties occur.
Tedious, deliberate and exacting are the best words that describe a rice plant breeder’s work. Patience is also a big factor in developing the rice variety and in hurdling the requisites by a national council that issues the go-ahead edict for its commercial use.
Breeder’s arena
Determining for only a few days how a breeder works in developing new varieties appear just but a superficial initiation. The truth is that it takes seven to 11 years before a new rice variety is developed and approved for release.
Alfonso’s “arena” is of modest facilities: a small field area, seed box or pots for growing the rice plants to be used as parents, a shaded area for emasculation of the flowers, and a protected area for keeping the pollinated female parents until the grains are ready for harvest.
In earlier times, the farmers themselves were breeders of rice varieties. Although they knew not much of the whole process and lacked the modern breeders’ methods and techniques, they were nevertheless successful in generating better rice varieties then.
“The breeder, once he starts working, envisions the desired output even before they make the actual crosses,” Alfonso said. “He is clear on the idea how the variety will stand in the field (plant height), how long it grows from sowing until it is ready for harvesting (maturity), how much grains it will produce per hectare (yield), what insect pests and diseases it will be able to ward off (pest resistance), and what grain qualities must be developed to be acceptable to farmers and the consumers.”
Two or more existing varieties are used for cross-pollination. The combination of the traits produces the envisioned off spring, he said.
“We make the crosses by selecting two parent varieties and designating them as either the male or female parent. The male parent provides the pollen while the female provides the egg,” Alfonso explained.
Further, he said, since rice is naturally self-pollinated, the female parent needs to be “emasculated”. This means the male parts of the flower (called anthers) are physically removed before they are ready to shed the pollen.
Emasculation, he explained, can be done by making a diagonal cut along the flower that has not undergone self-pollination, and removing the six anthers using a pointed object such as a needle or a very thin bamboo stick.
“But nowadays breeders use emasculator machines that use air vacuum allowing them to make hundreds of cross combinations,” he said.
Continuing, he said once the rice panicle bearing the emasculated spikelets appear, it is covered to protect them.
“We pollinate it using the pollen from the male parent the following day. We do this by putting together the plants side by side and the male panicle is shaken so that its pollen will fall in the emasculated spikelets,” Alfonso said.
Timing is of the essence in the practice of “pollen shedding.”
“It is usually done mid-morning until before noon. After that manual pollination, the panicle is again covered and the plant is provided with proper care until the ‘hybrid’ grains mature in about 20-25 days”, Alfonso said.
(To be concluded)
