Different aged Anatolian black pine [Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe] individuals to summer drought response

In this study, it was aimed to determine the drought tolerance of different aged Anatolian black pine [Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe] individuals within the Isparta Regional Forest Directorate. Three different age classes and growth stages of natural Anatolian black pine individuals were studied under the same growing conditions. Soil water content, midday water potential and water potential components (water potential at turgor loss point and osmotic potential at full turgor, free water content at turgor loss point, relative water content at turgor loss point, symplastic water content per unit dry weight, relative water content, and dry weight fraction) were determined in shoot samples taken in May, July and September. In addition, chlorophyll pigment content was determined in summer, the dry period. Soil water content, which was high in May (average 19.2%), decreased in July (average 6.4%), along with midday water potential (average -1.8 MPa and -2.5 MPa). Generally, first age class (about 13 years old) individuals of Pinus nigra exhibit significantly higher midday water potential (May: –1.4 MPa and July: –2.2 MPa). Among the water potential component, the water potential at turgor loss point in July was highest in the first age class (-2.5 MPa) and lowest in the second age class (-3.2 MPa). Chlorophyll pigment content in July was also found to be lowest in the second age class. In conclusion, it can be said that individuals of the Anatolian black pine in the first age class exhibit lower drought tolerance in response to decreasing water content during the dry season.