Super tuber: full-size spuds from bean-size bud

A new development in horticulture has made planting potatoes as simple as sowing peas or beans - and there isn't a much simpler operation in the home garden than that.

Indeed, the seed potatoes involved are little bigger than beans themselves; and we're talking about whole tubers, not cut-up pieces. They're called spud buds.

The important point for the home gardener is that planting small whole tubers is a lot simpler - and more successful - than cutting up large tubers into small pieces and drying them for several days before planting. The eventual harvest of full-size potatoes is said to be impressive because of the vigorous early growth associated with whole tubers. This stems from the fact that invading organisms find it difficult to penetrate the unbroken skin.

Growing trials show that in good garden soil each little tuber should produce up to 21/2 pounds of full-size spuds in a season. That suggests that a good harvest can come from a relatively small plot in the backyard.

The Geo. W. Park Seed Company of Greenwood, S.C., which is marketing spud buds, recommends that the little potatoes be planted about 10 inches apart and 4 inches deep. After the first sprouts appear, begin hilling the soil up around the plants to an eventual height of between 6 and 8 inches. This will provide ample loose soil for the developing tubers to expand. The Park Company offers two varieties of buds: Russet Burbank, which produces large white bakers, and Red Pontiac, a red-skinned boiler.

The program to create these small seed potatoes began in 1981 in the laboratory of Plant Genetics Inc. of Davis, Calif. There, a research team under Carolyn Sluis began producing the potatoes, using the micropropagation, or tissue-culture method, a method perfected in the last 10 years whereby thousands of offspring can be cloned from a small piece of tissue taken from a single plant.

One rare super-specimen, in other words, can readily be cloned into thousands of super-specimens.

From specially selected parents grown by Oregon State University, Ms. Sluis chose tips and grew them in a medium that stimulated the formation of microscopic plantlets. These were grown until the stems were about the thickness of pencil-lead. The stems were then cut into pieces, rerooted, and grown to maturity.

The resulting miniature plants now produce the marble-size tubers that, in turn, produce full-size plants bearing large tubers.