Alexandra Votteri, age 12, of Costa Mesa, Calif., for her question:

HOW ARE ORANGE TREES GROWN WITHOUT SEEDS?

More than three fourths of the oranges processed in the United States are used for frozen orange juice concentrate. The rest of the crop is either eaten fresh or used to make soft drinks, powdered instant orange juice, candied peel or marmalade. Some goes for candymaking while cannery wastes are used in livestock feed. Orange oil is also used for flavoring and perfumes.

There are two basic kinds of oranges: the sweet orange which originally came from China and the bitter or sour orange which came from India. Almost all of the oranges grown commercially in the United States are from sweet orange trees.

Oranges are considered to be commercially seedless if they contain five seeds or less. The Valencia orange, the most important late season orange of Florida and California  and the variety that accounts for almost half of the nation's annual crop  is considered to be seedless.

Completely seedless is the navel orange, which is really a double orange. A small second fruit that does not completely develop is found in one end of the main fruit. Called the Washington or California navel, it accounts for most of California's winter crop which is produced between November and April.

Sweet Valencia and navel oranges are reproduced by bud grafting part of the desired tree onto the root system of citrus trees that are hardier and more resistant to disease. The bitter orange is usually called into service for this root job, although sometimes the lemon or grapefruit roots are used.

Oranges must have tropical or subtropical climate. In subtropical locations, if the temperature drops below 25 degrees Fahrenheit, orchard heaters must be used. Central and southern Florida, the lower Rio Grande Valley in Texas and parts of southern California and Arizona are where most of the oranges are grown in the United States.

It costs less to produce an orange in Florida than in California, since Florida's rainfall is usually adequate. while irrigation is necessary in California. Labor costs are also higher and the crop yields are lower in California.

Leading orange growing state in the United States is Florida, where almost 225 million boxes of oranges are sold each year. California's count, winning second place, is about 47 million boxes while third place Texas comes up with 10 million boxes.

The United States is the world's largest orange¬growing country with more than 286 million boxes produced each year. Brazil comes in second with 138 million boxes while Japan and Spain place third and fourth with 114 million boxes and 79 million boxes.