The search for cultivated truffle could put some pigs out of work

The romantic fields and forests of the Piedmontese hills in northwest Italy, where farming traditions go back to Roman times, have long been the breeding ground for some of the highest delights of Italian cuisine.

Perhaps the most sought-after and seductive ingredient of Italian cooking is that elusive relative of the mushroom family, the truffle. It is called tartufo in Italian.

The white truffle found in Piedmont is the most treasured, while the black truffles of the mid-Italian region of Umbria or the Perigord in France are cheaper, more common, and less aromatic.

Aroma is the most distinctive characteristic of this unprepossessing little culinary deight. The truffle looks more like a runted potato than the ''diamond of the kitchen.'' Its pungent odor carries even when it is wrapped in linen and stored at near-zero temperatures.

The truffle can be detected easily as deep as five feet underground - its natural habitat - by the dogs or pigs used by truffle hunters. Once the truffle is located, the human truffle hunter goes about extracting his find as though he were on an archeological dig, scraping the dirt with a miniature hoe so as not to damage the precious tuber.

Truffles are fungi that grow attached to the roots of certain trees - oak, lime, willow, and poplar. They favor calcareous or limestone soil and uncontaminated ground, which means they are more and more difficult to find: Modern chemical fertilizers are death to truffle grounds.

Truffle hunting begins around mid-September and runs into March. In early October the first truffle festival is held in Alba, chief city of the Langhe and self-appointed white truffle capital.

The mysteries of how truffles grow have been studied over the centuries. Pliny the Elder and his Roman contemporaries stated simply that truffles were germinated by lightning. All one had to do was go truffle hunting after a storm.

Eighteenth-century botanists experimented on the possibility of growing truffles, even though there were plenty then.

There is no doubt that truffles were more abundant a hundred years ago. Brillat de Savarin, French gourmet of the 19th century, declared that before the French Revolution the only people who could afford truffles were the aristocracy. Nevertheless he suggested a recipe for truffle-stuffed turkey.

Today truffle eating is restricted to a light shaving of truffle over almost any dish from the classic Piedmontese fontina cheese fondue to spaghetti, rice, or fillet steak. This exquisite and unforgettable but all too brief encounter today means an additional $10 on the bill.

Gourmets need not despair, however. The truffle world has enough dedicated researchers to ensure its future. The Environment and Wood Plant Institute of Turin, under the guidance of Prof. Mario Palenzona, has successfully experimented with growing tartufi.

The institute sells saplings whose roots have been impregnated with truffle spore. ''These must be planted in suitable soil,'' the professor explains, ''and their growth must be carefully monitored. No kind of contamination or foreign spore must be allowed in that soil.''

After about three years - the experiments have not yet indicated the exact period of growth needed to produce a truffle - the first crop should be ready. A truffle festival in Asti, one of Alba's neighboring and rival truffle towns, boasted the first cultivated truffle recently.

For those who stick to traditional truffle hunting one prerequisite is a good dog. Although dogs are habitually used in the Piedmont, pigs are often used in other regions. They need no training.

A group of scientists in Munich has analyzed the truffle minutely and concluded that one of its ingredients is a substance present in the saliva of a male pig on the lookout for a mate. Thus an obvious choice for truffle hunting is a female pig, but she must be held back from devouring the seductive truffle.