Silent Running Trailer

Silent Running is a 1972 environmentally-themed American post-apocalyptic science fiction film starring Bruce Dern, featuring Cliff Potts, Ron Rifkin and Jesse Vint. It was directed by Douglas Trumbull, who had previously worked as a special effects supervisor on science fiction films, including 2001: A Space Odyssey and The Andromeda Strain.
Plot
In the future all plant life on Earth has become extinct. A few specimens have been preserved in enormous, greenhouse-like geodesic domes attached to a fleet of American Airlines space freighters, currently just outside the orbit of Saturn. Freeman Lowell (Bruce Dern), one of four crewmen aboard the Valley Forge, is the resident botanist and ecologist who carefully preserves a variety of plants for their eventual return to Earth and the reforestation of the planet. Lowell spends most of his time in the domes, both cultivating the crops and attending to the animal life.
Lowell and the surviving drones – which he nicknames Huey (Drone 2) and Dewey (Drone 1) after the cartoon characters – set out into deep space to maintain the forest. Lowell also reprograms Huey and Dewey to plant trees and play poker. Huey is damaged when Lowell accidentally collides with him while driving a buggy recklessly, and Dewey sentimentally refuses to leave Huey's side during the repairs. As time passes Lowell is horrified when he discovers that his bio-dome is dying, but is unable to come up with a solution to the problem. When the Berkshire – another space freighter waiting to see if the Valley Forge has survived the trip – eventually re-establishes contact, he knows that his crimes will soon be discovered. It is then that he realizes a lack of light has restricted plant growth, and he races to install lamps to correct this situation. In an effort to save the last forest before the Berkshire arrives, Lowell jettisons the dome to safety. He then detonates nuclear charges, destroying the Valley Forge. The final scene is of the now well-lit forest greenhouse drifting into deep space, with Dewey tenderly caring for it, holding a battered old watering can.