Chloroplast DNA variation and pollen contamination in a Pinus brutia Ten. clonal seed orchard: implication for progeny performance in plantations

Kaynakça (2)

1. 36 Friedman and Adams (1985) 12.5 16 Isozymes (21) 21 El-Kassaby et al. (1989) Pinus sylvestris Pinus sylvestris Pseudotsuga menziesii 12.5 2 Isozymes (11) 49 Adams et al. (1997) Picea abies Quercus robur 13.2 4.5 nSSRs (6) 70 Buiteveld et al. (2001) Pinus pinaster Pinus thunbergii 11.8 0.5 RAPDs (28) 2 Goto et al. (2002) Pinus brutia Pinus pinaster 11.2 4 nSSRs (3) Kaya et al. (2006)
2. Fernandes et al. (2008) Pinus sylvestris Pinus koraiensis 13.7 1 nSSRs (13) 25 Feng et al. (2010) Pinus brutia 17.8 cpSSRs (6) 39 Present study earlier seed orchard studies in forest trees. Moreover, another study based on allozymes and carried out in another seed orchard of the same species within the same region showed 85.7% pollen contamination (Kaya et al., 2006). The pollen contamination level in the present seed orchard was much lower than that reported by Kaya et al. (2006). The high contamination level of the latter orchard reported by Kaya et al. (2006) may be due to its relatively young age (11 years old) as well as to 2 neighboring stands located about 100 m away from the studied orchard. Harju and Nikkanen (1996) estimated 48% pollen contamination in a P. sylvestris seed orchard isolated from other stands by about 2 km. Pakkanen et al. (2000) in Picea abies and Slavov et al. (2005a) in Pseudotsuga menziesii also estimated pollen contamination levels in 3 different years and the mean contamination level was 70% and 35.3%, respectively. Although contaminant pollen generally has a lower breeding value than pollen originating from the seed orchard clones, the assessment of genetic quality of incoming pollen from outside stands is puzzling. If the genes are introduced to a seed orchard via alien pollen that originated from populations maladapted to the habitat of the offspring establishment, gene flow may reduce the fitness of the offspring and seriously affect the survival and production of operational plantations. Pollen contamination level depends on several factors, including the amounts of pollen production inside an orchard, the flowering synchronization among the orchard clones, the timing and duration of female cone receptivity of orchard clones relative to other pollen sources, the level of pollen production in neighboring stands, and annual weather variation (such as wind direction, temperature, and rainfall) during the period of male conelet maturation and female conelet receptivity (Harju and Muona, 1989; Burczyk et al., 2004b; Alizoti et al., 2010). The da