PRESERVING THE SEASON

The hint of fall touches the air, and in step with long tradition, many Americans are bringing out now-empty Mason jars to put up a few fruits and vegetables for the winter.

With visions of gleaming rows of canned peaches, pears, tomatoes, relishes, and butters, they head for the back garden - or for the nation's many back roads that snake between fields rich with harvest.

Some buy just-picked produce from the roadside stands. Or, at prices considerably below those in the supermarkets, they stop at the signs advertising ''pick-your-own'' - peaches, raspberries, blackberries, tomatoes, corn, apples, pears.

Later, converging at the stand to have the produce weighed and priced, they share recipes and talk of the pleasures of picking and preserving their own fruits and vegetables.

Then, in long afternoons and evenings in sweet-smelling kitchens, the harvest is washed, peeled, sliced, mashed, or strained - and at last cooked and ladled into the clean, steaming jars. Tightly sealed, they are placed fondly on the shelf - next to the strawberry jam put up in June.

There is special meaning to the rich dishes made from these peaches, pears, colorful strawberries, and apples, for they evoke memories of picking the fruits in the fall and preparing them carefully for the sparkling jars that will line the shelves of the pantry.

Aromas, forgotten for a while, waft from the kitchen as carefully chosen foods are opened and prepared for the traditional holiday dishes - or to be proudly served to special company.

Family recipes are consulted, old methods are honored, and the handpicked nuts and berries of last summer are used generously - even with some extravagance - to suit the occasion.

Growing food and gathering it is tied to the passage of the seasons and to the economics involved. But when winter comes the, pleasure of sharing the results of a handpicked harvest are many.

Sharing food that's been prepared from scratch with a gathering of family and friends is part of the reward of such simple homespun projects - and is often the final goal of these foods.

Communal harvesting, followed by eating ''participation dishes,'' in which each individual person must break a piece from the whole or stir a final seasoning into his own dish, involves each person in the task of preparation as well as eating.

In these days of plenty, such sharing helps retain the interdependent feeling found in cooperative projects of simple farming work or kitchen chores - putting up nature's plenty for the long winter season when friends gather around the hearth and cook and eat together.

Nor does it need to be contrived cooking. The ingredients lend themselves to old and favorite dishes that have been prepared and eaten for generations: The recipes have been handed down from grandmother to mother to daughter.

Made with love, warmth, and nostalgia, each jar of jam, jelly, pickles, or pumpkin is a happy addition to an ordinary meal - and a fine gift for friend or neighbor. Such gifts are highly prized and rare, for their like is not to be found in the largest supermarket.

Best of all, perhaps, is knowing that few gifts are as welcome and as appropriate a gesture of friendship as a gift from the kitchen. Friends just home from vacation or a long trip appreciate a jar of simple, well-preserved fruit. And what better way to welcome new neighbors than with a home-preserved delicacy from your larder? That is a tradition that is good today.