where some quantity of this flavanone was found in nectar clones but not in the
fruits. Finally, rutin was one of the most abundant compounds determined in the
fruits of the same “Oblačinska” sour cherry clones and its content was highest in
clone II/2, in both nectar and fruit [64, 114]. As it was stressed out, no matter that
floral nectar is secreted through intrafloral nectaries as a phloem solution [115] and
cherry fruit is formed form ovary within the flower, it seems that those two processes
are quite different and fully independent. In fact, this result is expected, because
deciduous fruit trees, to which sour cherry belongs, have accumulated necessary
minerals and organic compounds by the end of the previous growing season and use
these reserve nutrients to support initial growth and development in the following
spring. Thus, during flowering time (when leaves are just started to expand and are
without photosynthetic competence), reproductive development is under total reliance on reserves stored within the tree [116]. On the contrary, during sour cherry
fruit development (which occurs %55 days from pollination to fully ripe fruit),
leaves are fully developed and are having the main role as the main source of
photo assimilates [117].
5
Conclusion
Except few studies, not much was done in the analysis of cherry nectar. Sweet cherry
was not an object of any study so far, so the results of this chapter are based on sour
cherry nectar. According to the chemical analysis of our model plant’s (“Oblačinska
sour cherry”) floral nectar, it can be concluded that selected clones of this cultivar
showed different sugar and polyphenolic profile, where constituents showed
big variation. In sugars, fructose, glucose, and sucrose were the most abounded,
while arabitol, rhamnose, arabinose, turanose, gentiobiose, panose, melezitose,
and matotriose, together with galactitol and mannitol, were in minor quantities.
Regarding polyphenols rutin, naringenin and chrysin were found in the highest
levels. Only rutin, pinocembrin, and galangin, together with ( )-cis, trans-ABA
were detected in all nectar samples. Probably the cause of unequaled nectar composition (both for polyphenolics and sugars) in sour cherry is its hybrid origin (segmental allotetraploid between Prunus cerasus and Prunus fruticosa) and unstable
inheritance.
In the future, nectar chemical composition, could be a breeding aim for creating
a cultivar that will attract pollinators the most, and thus ensuring high yields, or
have components that can protect plant from economically important bacteria/
viruses/fungi. Besides, this chapter would like to support and encourage scientists
to analyze nectar for all other components and connect it with the pollenizer
preference.
Also in the following years, nectar of sweet cherry, and other minor cherry
species like European dwarf cherry (Prunus fruticosa Pall.), mahaleb cherry (Prunus
mahaleb L.), and duke cherry (Prunus  gondouinii Rehd.), and/or other agricultural plants, should be analyzed in details and connect it with honey quality.
29 Sugar and Polyphenolic Diversity in Floral Nectar of Cherry
767
fruits. Finally, rutin was one of the most abundant compounds determined in the
fruits of the same “Oblačinska” sour cherry clones and its content was highest in
clone II/2, in both nectar and fruit [64, 114]. As it was stressed out, no matter that
floral nectar is secreted through intrafloral nectaries as a phloem solution [115] and
cherry fruit is formed form ovary within the flower, it seems that those two processes
are quite different and fully independent. In fact, this result is expected, because
deciduous fruit trees, to which sour cherry belongs, have accumulated necessary
minerals and organic compounds by the end of the previous growing season and use
these reserve nutrients to support initial growth and development in the following
spring. Thus, during flowering time (when leaves are just started to expand and are
without photosynthetic competence), reproductive development is under total reliance on reserves stored within the tree [116]. On the contrary, during sour cherry
fruit development (which occurs %55 days from pollination to fully ripe fruit),
leaves are fully developed and are having the main role as the main source of
photo assimilates [117].
5
Conclusion
Except few studies, not much was done in the analysis of cherry nectar. Sweet cherry
was not an object of any study so far, so the results of this chapter are based on sour
cherry nectar. According to the chemical analysis of our model plant’s (“Oblačinska
sour cherry”) floral nectar, it can be concluded that selected clones of this cultivar
showed different sugar and polyphenolic profile, where constituents showed
big variation. In sugars, fructose, glucose, and sucrose were the most abounded,
while arabitol, rhamnose, arabinose, turanose, gentiobiose, panose, melezitose,
and matotriose, together with galactitol and mannitol, were in minor quantities.
Regarding polyphenols rutin, naringenin and chrysin were found in the highest
levels. Only rutin, pinocembrin, and galangin, together with ( )-cis, trans-ABA
were detected in all nectar samples. Probably the cause of unequaled nectar composition (both for polyphenolics and sugars) in sour cherry is its hybrid origin (segmental allotetraploid between Prunus cerasus and Prunus fruticosa) and unstable
inheritance.
In the future, nectar chemical composition, could be a breeding aim for creating
a cultivar that will attract pollinators the most, and thus ensuring high yields, or
have components that can protect plant from economically important bacteria/
viruses/fungi. Besides, this chapter would like to support and encourage scientists
to analyze nectar for all other components and connect it with the pollenizer
preference.
Also in the following years, nectar of sweet cherry, and other minor cherry
species like European dwarf cherry (Prunus fruticosa Pall.), mahaleb cherry (Prunus
mahaleb L.), and duke cherry (Prunus  gondouinii Rehd.), and/or other agricultural plants, should be analyzed in details and connect it with honey quality.
29 Sugar and Polyphenolic Diversity in Floral Nectar of Cherry
767