Examination of self-compatibility in promising plum (Prunus domestica L.) genotypes developed at the Fruit Research Institute, Čačak

- Self-compatibility was examined using fluorescence microscopy and fruit set.
- Genotypes 32/21/87 and 'Nada' were partially self-compatible, while 38/62/70, IV/63/81, 34/41/87 and 22/17/87 were self-compatible.
- Associations between reproductive parameters were identified.
- Genotype, year and their interaction influenced the studied parameters.
- The results obtained using two different methods were highly consistent.

The self-compatibility of six promising plum genotypes (hybrids 38/62/70, IV/63/81, 32/21/87, 34/41/87 and 22/17/87 and cultivar ʻNada') was examined during the period 2009-2011 through quantitative evaluation of parameters of in vivo pollen tube growth and fruit set. Mean daily temperatures were recorded during the flowering period. All genotypes showed good average in vitro pollen germination (36.34-38.63%) except the cultivar ʻNadaʼ (25.64%). The lowest values for in vivo pollen tube growth parameters - except with respect to number of pollen tubes in the upper third of the style ‐ were found in hybrid 32/21/87 and cultivar ʻNada'. The same genotypes also had the highest numbers of incompatible pollen tubes. The average number of fruit set ranged from 1.25% (hybrid 32/21/87) to 31.08% (hybrid 34/41/87). All studied parameters depended on genotype, year and their interaction. There was a significant positive correlation between the number of fruit set and the number of pollen tubes in the base of the style. The number of pollen tubes in the ovary had a significant positive impact on percentage of pistils with pollen tube penetrating the nucellus 240 h after pollination and on number of fruit set. Based on these data hybrid 32/21/87 and cultivar ʻNadaʼ were classed as partially self-compatible and hybrids 38/62/70, IV/63/81, 34/41/87 and 22/17/87 as self-compatible.