The Unusual Mechanism of Alternate Bearing in the Pistachio1

Abstract

In contrast to other fruit tree species that produce flower buds in limited quantity at the same time a heavy crop is being produced, the pistachio ( Pistacia vera L.) produces abundant inflorescence buds which, for the most part, abscise during the summer. Thus, alternate bearing in the pistachio is effected by a unique mechanism. Evidence is presented which suggests that the abscission of the inflorescence buds is the result of assimilate depletion when a heavy crop is produced.