Constraints on seed production in Pistacia mutica Fisch. and Mey. (Anacardiaceae).

摘要

Pistacia mutica is one of the main species used as rootstock for Pistacia vera and very well-suited for reforestation of west slopes of Iran. Alternate bearing and mainly low seed set even in on-years are two big dilemmas that can be related to incompatibility. Flower and fruit samples were harvested from open pollinated trees then fixed and processed for assessing the pollen tube pathway, flower and fruit abnormality and abortions. In each cluster, two forms of small (abnormal) and normal flowers were observed. Most of the degenerated samples dropped in the first four weeks after pollination. Degenerated early nucellus tissue and lack of megaspore mother cell were dominant in abnormal samples. Degenerated samples of normal florets consisted of samples with no embryo sac (ES), deformed embryo sac, an early degenerated embryo, deformed endosperm in the early stages of development, and embryo destruction during the globular stage. Embryo sac without an endosperm tissue, embryo and endosperm growth interruption or delay at the late growth stage before fruit cavity filling were other examples of fruit abnormalities. Thus, flower and fruit abnormality and abortions caused by unknown factors occurred at pre- or post-fertilization durations. Abortion of small florets may be related to lack of nutrition and fruit growth substances..