Evaluation of Flowering Pattern and Pollen Quantity of Some Pistachio Male Genotypes Under Qazvin Environmental Conditions

Insufficient pollination is one of the main reasons for the low pistachio yield in the country. Differences in the flowering time of male and female pistachio trees, the inadequate ratio of male to female trees in the orchard and lack of proper orientation can significantly reduce the efficiency of pollination and consequently the yield of pistachio trees. The simultaneous flowering of male and female trees is essential for successful pollination and fertilization. In this study, 56 male pistachio genotypes in Yezbar pistachio station, Qazvin Agricultural and Natural Resources Research and Education Center, Qazvin province during 2020 were examined and their flowering characteristics evaluated. For this purpose, three branches of each genotype labeled in the spring and phenological stages such as flowering beginning, full bloom and end of flowering were examined. Also, male catkins were collected during the flowering period and indicators such as wet and dry weight of the inflorescence, the weight of pollen grains per inflorescence and the number of inflorescences on the branch measured. The results showed that the flowering period of the female Kalebozi cultivar in the orchard was 11 days. Flowering began on April 21, the full bloom stage on April 26, and the end of flowering on May 1. The male genotypes also had a significant difference in all traits except the fresh weight of the inflorescence at the level of 1%. Evaluations showed that among the 56 male genotypes, 530-2 and 522-2 were the earliest and the latest flowering genotypes, respectively. The longest flowering period with 13.3, 12.6 and 12.3 days were related to genotypes 526-4, 516-1 and 522-3, respectively, followed by the genotypes 502-5, 529-5 and 529-1. The shortest flowering period belonged to 521-3 with 5 days. The flowering period of genotypes 502-5, 526-4, 516-1 and 522-3 was completely consistent with the flowering of Kalebozi cultivar and covered 100% of the flowering of this female cultivar. In addition, genotypes 526-4, 526-6, 522-3, 508-3, 518-6, 525-6 and 508-4 had higher dry weight of inflorescence and production of pollen grains. In terms of the number of catkins, the genotypes 529-5, 528-4, 508-4, 526-4, 518-6, and 509-4 had more than three catkins. Genotype 526-4 can be introduced as the superior genotype for pollination of Kolebozi cultivar due to its long flowering period and being synchronous with Kolebezi cultivar and also having more pollens and catkins.