The Role of Seed Abortion and Parthenocarpy in the Production of Blank Pistachio Nuts as Affected by Rootstock1

Production of blank nuts in ‘Kerman’ pistachio was the result of both parthenocarpy and seed abortion, the latter being responsible for the major portion. The degree of parthenocarpy was relatively uniform throughout the entire tree population, but seed abortion varied according to the history of blank production of the individual trees. Production of blanks, therefore, appeared to be governed by the seedling rootstocks.