Physiological properties of service tree (Sorbus domestica L.) seeds as affected by fruit size

Statistically significant differences were achieved in length and width of service tree fruits with different weight. Small fruits had statistically significant higher fruit shape index (0.98) than medium large (0.94) and large (0.91) from which can be concluded that small fruits have 40 more roundish shape. Number of full seeds in fruit was statistically significant higher for large fruits (2.62 piece) than medium large (1.81 piece) and small (1.46 piece) fruits. Within all fruits positive and very high correlation was obtained between fruit length and width (r=0.92), fruit length and weight (r=0.93) and fruit width and weight (r=0.98). There is negative and statistically significant correlation between fruit weight and fruit shape index (r=-0.47). Statistically significant difference was obtained in length of seed radicle from fruits of different weight after 120 days of stratification. Seeds from large fruits had statistically significant bigger radicle length (3.89 mm) than seed from small (2.88 mm) and medium large (3.27 mm) fruits. Weight of air-dry seed increases with fruit weight. No statistically significant difference was found in mean germination time (MGT) from fruits of different weight although seed from bigger fruits has germinated 4 days earlier than seed from medium large fruits and 3 days earlier than seed from small fruits. Average time of seed germination for all fruits was 107 days. On seed from all fruits negative and significant correlation (r=-0.66) was found between radicle length after 120 days of stratification and time needed for beginning of germination. With increase of seed weight in air-dry condition percentage of water absorption statistically significantly decreases. After 120 days of stratification at 3ºC, seed from large fruits (16-20 g) had highest percentage of germination (83.7%). Laboratory germination of service tree seed increases with fruit size