Acta 93.indd - Výzkumný ústav Silva Taroucy pro krajinu a okrasné ...

Fig. 1 Amygdalus nana L. – individual with fruitAn individual was considered a ramet or a set of ramets(growing from hypocotyl – basal part of ramet) totally orpartially separated from the other ramets and sets of ramets.Individuals were selected randomly (within polycormons) inboth localities, and the selected individuals were labelled (40individuals per locality). In the Vŕšok II. Hill, the A. nanapopulation was scattered to more polycormons, therefore, welabelled the individuals within the fifth polycormons there.The dwarf almond population in the Drieňová hora NatureReserve was more or less continuous (one polycormon).Therefore, we counted the amount of flowers and fruits on theselected individuals there. The fruit set was calculated from thefound A. nana flowers and fruits, as the ratio of the developedgenerative diasporas (fruits) to reproductive organs (flowers).RESULTS AND DISCUSSIONThe fruit set of A. nana in the year 2007 was relatively low(2.41 %) in the Vŕšok locality and 0.89 % in the Drieňováhora (Table 1, Fig. 5). The mean of flower number in the Vŕšokwas higher (72.14) than in the Drieňová hora (23.33). Onthe selected ramets, fruit production was very low. While 21fruits were found in the Vŕšok II. hill (16 degenerated), onlyFig. 2 Amygdalus nana L. – flowering individual5 fruits were developed to mature stage in the Drieňová horaNature Reserve. However, all these fruits were degenerated.As it has been mentioned above, the genus Amygdalus isself-sterile, that means that fruit production is rare, even incase of the ones not developed completely (they finish withdeveloping in a certain phase, and dry later). In the year 2008the fruit set of A. nana increased in both localities – it reached8.06 % in the Vŕšok, and 7.28 % in the Drieňová hora (Table1, Fig. 6). It was probably caused by more favourable climaticconditions. Different ecological conditions could have beena possible source of fruit set value variability at the selectedhabitats.Similarly, Krchňavá et al. (2003) report a very low fruit setfrom the Vŕšok locality (only 0.7 %), with the fruit set valuecalculated from normally developed fruits. Also other authorsindicate low fruit set in similar species. In C. fruticosa, Ághová(2000) found a relatively low fruit set on the Pyramída hilllocality (the Tríbeč Mts.) during vegetation seasons 1997–1999 (fruit set was 0.94 to 2.87 %). The fruit set decreasedwith increasing rainfall during flowering and with increasingtemperature. Guitián et al. (1992) studied fruit set of Prunusspinosa, P. mahaleb and Crataegus monogyna in north-westernIberian Penninsula. They found a very low fruit set in thementioned species (