Conservation of the genetic diversity of Turanga poplars for restoration of population sustainability in desert and semi-desert regions of Kazakhstan

For the first time in Kazakhstan, a comprehensive study was conducted on the conservation, seed propagation and determination of the sex of seedlings in the juvenile stage of development to restore population stability of Populus pruinosa Schrenk and Populus euphratica Oliv. The seeds of Turanga poplars are classified as intermediate, meaning they lose viability relatively quickly. The optimal methods for long-term preservation have been identified. Seeds lose their germination capacity within 3–6 months under traditional storage conditions of +20 °C and –20 °C. By contrast, cryopreservation in liquid nitrogen at –196 °C was effective: seed germination and germination energy remained stable and comparable to the control after 12 months, and even after 5 years, across all species studied. It is crucial to determine the sex of plants at early developmental stages to restore declining populations and urban landscape areas. The polymerase chain reaction (PCR) method, using ISSR primers IS A02 and IS A71, was employed to identify male and female individuals during the juvenile seedling stage. In Populus pruinosa Schrenk, 14 male and 10 female genotypes were identified, while in Populus euphratica Oliv., 6 male and 6 female genotypes were detected. To support the restoration of Populus euphratica Oliv. and Populus pruinosa Schrenk populations, 400 male and female seedlings were cultivated in pots. Additionally, to preserve genetic diversity, 100,000 seeds of both Turanga poplar species were stored under cryopreservation conditions.