Morphological variation in local pears from north-western Spain

The germplasm pear bank in north-western Spain includes 221 accessions collected in the region between 1978 and 1981. Four reconstructed populations (RPPs) were detected by simple sequence repeats (SSRs) using a Bayesian method, two of which included French and English cultivars introduced to north-western Spain after reconquest by the Muslims in the 10th century. We studied 22 morphological and 15 phenological characteristics. We used principal component and cluster analysis to identify and classify the main origins of variability, these being flowering time, size and shape of fruit, time of harvesting, percentage of russeting and firmness of the flesh. Genetic differentiation between reconstructed populations, detected by a Bayesian method using SSRs, was also found in morphology, though with a great diversity inside each RPP that overlapped the main RPPs. This was consistent with the excellent quality of the reference cultivars apparently involved in the origin of the two main RPPs, ‘Mantecosa Hardy’ and ‘Williams’, suggesting that the contribution of foreign cultivars and subsequent selection by farmers have led to common phenotypic characteristics in both main groups. The introduction of cultivars from France and the United Kingdom could have occurred before 1746, when the first references to local cultivars related to both main RPPs were made. Furthermore, hybridisation with local species could explain part of the variability detected, which can be exploited for breeding programmes and local productions, nowadays focused on a reduced number of cultivars.