STUDIES ON THE FERTILIZATION BIOLOGY OF 'UZUN' AND 'SIIRT' PISTACHIO CULTIVARS IN THE MANISA ECOLOGY

This study aimed to determine the most suitable pollinator types for the ‘Siirt’ and ‘Uzun’ pistachio varieties in the Demirci district of Manisa. ‘Atlı’, ‘Buttum’, ‘Uygur’, and the naturally growing ‘Melengiç’ (Pistacia terebinthus L.) types were used as pollinators. According to phenological observations, the flowering periods of all pollinator types and female varieties occurred between April 5–25. The ‘Uzun’ variety overlapped in flowering time with the ‘Uygur’ type, while the ‘Siirt’ variety overlapped only with the ‘Buttum’ type. According to the TTC test, the pollen viability rates were 90% and 93% for ‘Melengiç’ and ‘Buttum’ types, respectively, while ‘Atlı’ and ‘Uygur’ types had viability rates of 81% and 79%. The IKI method showed that all pollinator types had high pollen viability levels. The pollen germination rates ranged between 45% and 62%. For the ‘Uzun’ variety, the ‘Uygur’ type had the lowest fruit drop rate (68%) and was evaluated as the best pollinator. On the other hand, the highest fruit drop rate (85%) was observed in the open-pollination treatment. For the ‘Siirt’ variety, fruit drop rates were higher compared to the ‘Uzun’ variety, with the lowest drop rate observed in the ‘Buttum’ combination (78%). In terms of fruit set, all pollinators significantly improved the fruit set rate for the ‘Uzun’ variety, with ‘Uygur’ and ‘Melengiç’ producing the best results. For the ‘Siirt’ variety, ‘Buttum’ and ‘Atlı’ pollinators achieved higher fruit set rates compared to the other pollinators and open-pollination treatment. Keywords: Pistachio, pollinator, fruit set, pollen, fertilization biology