Pollen Self-incompatibility and Determination of Appropriate Pollinizer for Quince (Cydonia oblonga Mill.) Cultivar Isfahan

In Iran quince cultivar Isfahan is the dominant commercial cultivar that demonstrates low fruit set and limited crop load in the orchards without pollinizers. This research was performed to determine the self–incompatibility and the most suitable pollinizer for Isfahan cultivar. For this purposes, effects of four different pollinizers including KM1, PK2, KVD2 and NB4, and two control treatments, self pollination and open pollination were evaluated on fruit set and fruit quantitative and qualitative characteristics of cultivar Isfahan for three years (2006-2008). Based on the results of mean comparison of fruit set percentage, there were a significant difference among different pollination treatments, except KVD2 and NB4. The maximum percentage of fruit set was 23.42 which gained by KM1 genotype, and the minimum 8.4% was related to the self pollination. The mean comparison of self pollinated treatments on fruit weight showed a significant difference between KM1 and other treatments. The KM1 genotype with high overlap blooming period and highest percentage of fruit set and seed number per fruit was recognized as the best pollinizer for quince cultivar Isfahan. Parallel assessment for isolation and evaluation of diversity in S locus of quince genomes revealed the presence of S alleles in this locus in most tested genotypes. Interestingly, more suitable quince genotypes for using as pollinizers, KM1 and NB4, contained two divergent S alleles in this locus.