Air New Zealand yesterday tested a jet fuel made from the jatropha plant as the airline searches for an affordable and environmentally friendly alternative to crude oil.

For two hours, pilots tested the oil, in a half-and-half blend with conventional jet fuel in one of the four Rolls-Royce engines powering a Boeing 747-400 aircraft — the first test flight by a commercial airline using jatropha oil. Rob Fyfe, Air New Zealand’s chief executive, called the flight a milestone in commercial aviation. “Today we stand at the earliest stages of sustainable fuel development and an important moment in aviation history,” he said. The project has been 18 months in the works.

Unlike biofuels made from crops such as soybeans and maize, jatropha needs little water or fertilizer and can be grown almost anywhere — even in sandy, saline or otherwise infertile soil. Each seed produces 30 percent to 40 percent of its mass in oil, meaning it has higher yield per acre than many other plant oils, specialists said.

The results of the flight — and two others planned by rival airlines in the United States and Japan in January — will be closely watched by an industry that is trying to shift toward renewable, low-emissions fuels.

A sharp rise in crude oil prices — to more than $145 a barrel in July — offer a strong incentive for the industry to reduce its exposure to volatile oil prices. But pressure to reduce carbon emissions has also driven the search for alternatives.

The International Air Transport Association, which represents 230 airlines, says it wants its members to use 10 percent alternative fuels by 2017. The association has the ambitious goal that airlines will be able to fly carbon-free in 50 years, with the help of technologies such as fuel cells and solar energy.

Such goals have ensured that research and development into greener flying have continued, despite the plunge in oil prices below $40 a barrel.

Having conducted a series of tests yesterday, Air New Zealand and its partners, the aircraft manufacturer Boeing, the engine maker Rolls-Royce and the technology developer UOP, a part of Honeywell, will review the results “as part of our drive to have jatropha certified as an aviation fuel,” said the flight’s chief pilot, Capt. David Morgan.

The hope is that the test results will lay the groundwork for jatropha to be commercially available in three to five years, executives from the companies said.

Virgin Atlantic in February became the first airline to test a biofuel blend in a commercial aircraft, using a 20-percent mixture of coconut oil and babassu nut oil in one of its four engines.

Two more airlines are to test their alternatives next month. Continental Airlines on Jan. 7 will conduct a test flight using a blend that includes algae and jatropha, the first biofuel test flight of a commercial airliner owned by a U.S. company.

And Japan Airlines is planning a test flight Jan. 30 using a fuel based on the camelina oilseed.

Together, the flights will test not only different sources of alternative fuel, but also their use in different engines. Attention has increasingly turned to fuels made from inedible crops, such as algae and jatropha, that can be grown without drawing on forested or arable land.

But even the potential use of jatropha has not been free of criticism, with some observers saying that farmers could be tempted to substitute edible crops for jatropha in the hope of getting better prices.

Algae may be free of this potential problem, but research into algae is not as far advanced, said an Air New Zealand spokesman, Mark Street, explaining the airline’s decision to focus on jatropha.

Air New Zealand, which aims to meet 10 percent of its fuel needs through sustainable biofuel by 2013, said the jatropha used on yesterday’s flight had been grown in Malawi, Mozambique and Tanzania.