Pollen dispersal in pistachio (Pistacia vera L.)

The distance and direction of pollen travel was studied to estimate the appropriate male to female ratio in pistachio orchards. A seedling tree, about 70 years of age, was used as a pollen source in Ankara, Turkey, and no other male trees were present. The time of pollen shed, pollen diameter, and pollen viability were determined. Pollen grains were captured on vaseline coated glass slides. A total of 32 traps were placed 2m above the ground at distances of 5, 10, 15, 20, 40 and 80 m from the male tree in each of four directions (east, west, north and south). Anthesis commenced on April 28, 1992. Peak pollen release occurred when 50-90% of the flower clusters reached anthesis. Pollen diameter was small (30.5 mu) and viability was high (86%). Wind blew primarily from the north-northeast, northeast and east-northeast with an average velocity of 3.4 m/sec. Accordingly, most of the pollen (80%) was trapped to the west of the pollinizer. Pollen concentration decreased dramatically with increasing distance from the source. Average pollen concentrations over the entire period were 1,137.9, 516.5, 388.6, 118.1, 53.8 and 18.9 grains grains/cm(2) at distances of 5, 10, 15, 20, 40 and 80 m respectively. From these data we estimated that an average of 1.2 viable pollen grains might reach a female flower at a distance of 20 m. A maximum distance of 20 m between pollinizers and female trees is suggested.