In February, 1966, Backster recorded what he believes to be emotional reactions in plants with a polygraph machine. Called the Backster Effect, the validity of this phenomena is still debated.
On 2/10/86, Cleve Backster's lab was visited by National Research Council's Committee on Techniques for the Enhancement of Human Performance. The NRC was evaluating enhancement and parapsychological studies conducted for the Army, so it is likely that Backster's research was involved with the government.
(National Research Council, Enhancing Human Performance, National Academy of Sciences, 1988, pg 193-8)
According to Swann, Backster maintained his intelligence connections, and Backster reported that the CIA was interested in his experiments.
Some of Backster's experiments are documented in "PRIMARY PERCEPTION: Cleve Backster's astounding mind/plant communication discovery!", Australian Lateral Thinking Newsletter,1996.