By Jennifer Smith

Electric-truck startup Nikola Corp. and Tesla Inc. both aim to wean the trucking industry off its decades-old dependence on diesel fuel, but the rivals are using two very different road maps.

Tesla plans to use its own technology to build the company's all-electric Semi truck, including batteries produced at its factory outside Reno, Nev., that supplies its passenger vehicles.

Nikola drew big attention to the electric-truck market this week as shares in the company soared after it began public trading through a merger, and it aims to be just as disruptive as Tesla with a plan to power big rigs through using batteries and hydrogen fuel-cell technology. But the company is building its future on partnerships with established industry manufacturers.

Phoenix-based Nikola has set up partnerships with equipment-maker CNH Industrial NV and automotive supplier Robert Bosch GmbH, which also have invested in the startup. Nikola plans to build a U.S. factory in Coolidge, Ariz., but initial production of its first semi trucks will be at a plant in Ulm, Germany, operated by IVECO, CNH's commercial vehicle brand.

Competing with established manufacturers while also changing the way trucks are powered is "a huge undertaking," Nikola Chief Executive Mark Russell said. "Every time we came to a challenge we talked to the established experts around the globe... It was just a really great way to scale the company up."

IVECO also will help Nikola establish a fueling network in Europe for its hydrogen-electric big rigs, Mr. Russell said. Those trucks, which are planned for production starting in 2023,are to be powered by hydrogen that passes through a fuel cell stack to produce electricity that sends energy to the vehicle's wheels.

"The reason hydrogen hasn't taken off is there isn't enough infrastructure to serve them if you bought one," Mr. Russell said. "We have to build the vehicle and we have to build the stations to refuel them."

Big-transport operators are lining up to test the electric trucks. Companies including Walmart Inc., FedEx Corp., United Parcel Service Inc., Ryder System Inc. and J.B. Hunt Transport Services Inc. have placed reservations for Tesla's Semi. Trucker U.S. Xpress Inc. and the U.S. subsidiary of Anheuser-Busch InBev SA have reserved hundreds of Nikola's hydrogen-electric trucks.

The companies haven't placed full orders, however, and the reservations can be canceled.

Don't expect to see the trucks on the road soon. The Semi was supposed to come out last year, but has since been pushed back to 2021. Tesla didn't immediately respond to a request for comment.

Nikola's first model, an electric-battery truck called the Tre, is also set to roll out next year, with the hydrogen fuel-cell model slated for 2023.

Transportation experts say it could be years before the vehicles gain traction in long-haul trucking, where high upfront costs and concerns about range are hurdles to adoption.

Diesel-powered trucks can go twice as far on a single tank of fuel as the Semi's maximum 500-mile range.

"We expect gradual increases in adoption rates, particularly for short-haul applications, and for the Class 8 tractor market, access to automotive scale will be key to driving costs down," said Tim Denoyer, vice president and senior analyst at transportation data provider ACT Research.

By 2030, electric and hybrid models could account for 6.8% of the North American market for heavy-duty trucks, which also includes vehicles such as garbage trucks, according to equipment research group Rhein Associates.

"The biggest question mark that always comes up for me is infrastructure, " said Rhein Associates analyst Andrew Wrobel. Truck stops "are designed to push diesel and gasoline. They are not set up to handle electric charging, especially for long-haul truckers, and they are not set up for hydrogen, to power fuel cells."

Write to Jennifer Smith at jennifer.smith@wsj.com