2018 ASHS Annual Conference

Determining the establishment success of a tree species requires conducting germination tests before using it in extensive horticultural programs. This is particularly critical in cold, arid or semi-arid climates where there is little or no top-soil. In the study, the germination performance of five Turkish red pine (P. brutia Ten.) provenances and one black pine (P. nigra subsp. nigra) provenance from Turkey were investigated after exposure to artificial cold temperature and water stress treatments. Cold treatments to decreasing temperatures (0, -5, -10, -15, -20 C) were conducted in an artificial freezer (ScienceTemp model 40-12A, Adrian, MI). The seeds were then sown in a Styrofoam block in a greenhouse where germination rate, speed, and other parameters were determined. Water stress treatments were conducted using polyethylene glycol (PEG) at five different osmotic potential levels (control, -0.2, -0.4, -0.6 and -0.8 Mpa). Seeds were placed in a germination room and the experiment was carried out at 25±1 °C under 12 h photoperiod. Germination counts were performed daily for 30 days and was determined to have occurred if the radicle protruded 2mm from the seed coat. In general, decreasing temperature decreased the germination rate. Antalya-Gundogmus provenance showed the significantly lower germination difference compared to other provenances in each temperature treatments. Higher osmotic potential decreased the germination rate. Control treatment had significantly higher germination rate compared to all other water stress treatment. P. nigra was significantly different compared to P. brutia provenances in control treatment. Results have strong horticultural implications for understanding the effects of water stress and temperature on germinations rates.