Study of some pollen genotypes viability and comparison of natural and manual pollination in pistachio (Pistacia vera L.)

In plants for more grain production, it is possible to use manual pollination in the absence of enough natural pollination. In pistachio, manual pollination can be a solution to the problem of yield reduction caused by pollen shortage. Here, the viability of several male genotypes and the effectiveness of manual and natural pollination were compared. 21 male genotypes were selected and the pollen size and tube growth were compared in a completely randomized block design. After 2.5 hours of culture, genotypes 13 (53.33%) and 17 (52.56%) had the highest germination rate and genotype 6 (110 μm) showed the highest pollen tube length. After 5 hours, genotype 21 (74.66%) had the highest germination rate and genotype 8 (150 μm) showed the highest tube length. Manual pollination with a mixture of pollen of high quality genotypes (21, 17, 13, 8 and 6) was performed on two female cultivars of Ahmadaghaei and Kaleghoochi and compared with natural pollination as a split plot design. In manual pollination all flowers had pollen, but in natural pollination, 67% of the flowers were free of pollen. The percentage of falling flowers and fruits in natural pollination (85%) was higher than manual pollination (79%) but, the percentage of fruit blankness in manual pollination (20%) was higher than natural pollination (% 1). It is possible that the high pollen density in manual pollination reduced the flowers drop and increased the number of fruits but, due to insufficiency of nutrients, many seeds could not grow, resulting in blank fruit production.