Variations in cone and seed phenotypic traits among and within populations of Aleppo pine in Jordan

Aleppo pine (Pinus halepensis Mill.) is one of the most valuable species in the Mediterranean basin and is mainly used in reforestation programs in Jordan to combat desertification. Currently little is known about genetic variation in this species in Jordan. Thus, the aim of the study was to assess inter- and intra-population variation in cone (cone length, cone width, cone weight, and number of seeds per cone) and seed traits (seed length, seed width, 100-seed weight and germination). For this purpose, four natural and five planted populations were considered, and cones were collected from 15 to 20 open-pollinated families in each population and eight traits were analyzed. The results showed significant (p < 0.05) inter- and intra-population variation in cone and seed traits. More of the variation was among populations than within populations. The natural populations exhibited relatively higher phenotypic variability in cone and seed traits than the planted populations. Cone and seed traits showed positive correlations with altitude but negative correlations with mean annual temperature, suggesting that altitudinal factor should be considered in future reforestation program. The findings demonstrate the presence of moderate genetic variation in seed weight, which can be exploited to initiate an improvement program for the species and for ex-situ conservation in gene banks. Establishment of field gene banks at various locations and environments is necessary to preserve genetic resources of Aleppo pine.