American consumers accustomed to skyrocketing prices and dwindling supplies of foreign-produced goods could be independent within a few years of yet another foreign commodity -- Iranian pistachio nuts. "We will approach independence by 1981 -- depending on our consumption habits," Morris Mahlmann, special products manager for Tenneco West, said recently. Tenneco is a major processor of the popular nut.

Americans ate 30 million pounds of pistachios last year -- two-thirds of which were imported from Iran, industry officials say.

Iranians began limiting pistachio exports about two years ago, forcing price increases by as much as 40 percent, Mahlmann said. Pistachios currently retail for about $5 a pound, he added.

Industry observers are buoyed by this year's U.S. pistachio harvest which exceeded 12 million pounds. Not only is the harvest increasing, but growers believe they have improved the product.

The American nut, a hybrid of the Iranian version, is about one-third larger and a greater percentage of the shells are split making them easier to open and eat.

The Iranian and Turks, who also export pistachios, dye their nuts red to cover an unattractive mottled shell. Developers of the American pistachio were able to come up with a sand-colored nut that doesn't need makeup.

Nearly all the American-grown pistachio nuts are produced in California, where some 31,000 acres were planted in the early 1970s. Many of the trees are grown as tax shelters because of their money-losing years. The trees begin bearing fruit five years but hit a production peak of about 70 pounds per tree in 15 years.

It is those trees that produced this year's crop, said Mahlman. "This is the best year we've ever had. The production curve is becomiing quite dramatic," he said.

"In 1981 we should have somewhere in the area of 25 to 30 million pounds, which would be roughly equivalent to what we have been consuming in the past. But it will be 1985 before we reach our full potential -- 50 to 70 million pounds -- and become fully capable of meeting our demand," he said.

"The pendulum will swing to where supply is going to equal demand and you have a different set of circumstances -- then there is a possibility the prices will soften," Manlmann said.