The early drought test on seeds of some Anatolian black pine (Pinus nigra arnold.) provenances collected in different years

This study investigates the effects of different water stress levels on the germination parameters of Anatolian black pine (Pinus nigra Arnold.) seeds. For this purpose, seeds from Denizli and Kütahya provenances were analyzed to determine their morphological characteristics (thousand-seed weight and seed moisture content) and germination parameters, including germination percentage (GP), relative germination percentage (RGP), and germination speed (GS), to identify drought-resistant provenances. Morphological analyses showed that the thousand-seed weight of Denizli provenance ranged between 15.2 and 22.9 gr, with a moisture content between 6.5% and 8.3%, while the thousand-seed weight of Kütahya provenance ranged between 20.4 and 23.7 gr., with a moisture content between 8.1% and 9.3%. Water stress levels were adjusted to 0, -0.2, -0.4, -0.6, and -0.8 MPa using polyethylene glycol (PEG)-6000 solutions. Germination tests were conducted over three different storage durations (2, 4, and 8-9 years), and the data were analyzed using variance analysis. The results revealed that as water stress levels increased, germination percentage, relative germination percentage, and germination speed decreased significantly. These reductions became more pronounced at water stress levels of -0.6 MPa and higher. Statistical differences in germination parameters (RGP and GS) were observed among provenances under water stress levels. However, storage duration did not have a significant effect on germination parameters (RGP and GS). Although the responses of seeds from Denizli and Kütahya provenances to water stress were generally similar, seeds from the Kütahya provenance exhibited higher GP and RGP values compared to those from the Denizli provenance. Therefore, the Kütahya provenance was evaluated as being more drought-resistant. This study demonstrates the existence of intra-species variation in drought resistance among Anatolian black pine provenances. Provenances identified as more drought-resistant are recommended for afforestation projects in arid and semi-arid regions to improve success rates.