U Republici Hrvatskoj šljiva zauzima treće mjesto po površinama i proizvodnji plodova. Sorte
šljiva zastupljene u hrvatskim voćnjacima često su tržišno neatraktivne ili su osjetljive na
virus šarke te je njihova proizvodnja nekonkurentna. Oplemenjivački program šljive u
Njemačkoj stvorio je nekoliko novih sorata šljiva (´Topstar´, ´Toptaste´, ´Haganta´, ´Jojo´,
´Tophit´) koje su tolerantne na virus šarke, a odlikuju se boljim pomološkim, fizikalnim i
kemijskim svojstvima. Agroekološki uvjeti značajno utječu na kakvoću plodova te je
potrebno poznavati adaptibilnost novih njemačkih sorata na agroekološke uvjete istočne
Hrvatske, gdje je veliki bazen uzgoja šljiva i gdje se šljiva tradicionalno uzgaja stoljećima.
Pomološka, fizikalna i kemijska svojstva mogu značajno varirati u pojedinim područjima
uzgoja, a s time je povezano i određivanje roka berbe za pojedine sorte. Neprikladan rok
berbe razlog je propadanja velikoga postotka plodova u voćnjacima jer ne postoje univerzalni
parametri za određivanje roka berbe.
Cilj ove disertacije bio je prikazati gospodarsku evaluaciju novih sorata šljiva (´Topstar´,
´Toptaste´, ´Haganta´, ´Jojo´, ´Tophit´) u agroekološkim uvjetima istočne Hrvatske te utvrditi
dinamiku promjena fizikalnih i kemijskih svojstava plodova tijekom zrenja i odrediti
optimalni rok berbe u odnosu na klimatske čimbenike.
Istraživanje je provedeno u pokusnome nasadu šljiva na pokušalištu Poljoprivrednoga
instituta Osijek, objekt Tovljač – istočno od Osijeka. Pokusni nasad posađen je 2005. godine.
U disertaciji je istraživano 6 sorata šljiva: ´Toptaste´, ´Haganta´, ´Jojo´, ´Topstar´, ´Tophit´ i
´Čačanska ljepotica´ cijepljenih na podlozi WaxWa. Razmak sadnje je 4 × 2,5 m. Uzgojni je
oblik popravljena vretenasta piramida. Sorte su posađene u tri reda, gdje je svaki red
predstavljao repeticiju. U svakom redu posađena su 4 stabla svake sorte koje predstavljaju
blok. Blokovi su randomizirani. U pokusnome nasadu nije uveden sustav za navodnjavanje te
su primijenjene standardne tehnološke mjere gnojidbe, njege i zaštite. Berba plodova bila je u
4 roka berbe počevši od trenutka promjene pokrovne boje ploda nastavljajući se u tri iduće
berbe svakih 5 – 7 dana. Istraživanje je trajalo dvije godine. Mjerenja su obuhvatila praćenje
klimatskih prilika, praćenje fenofaze cvatnje i dinamiku rasta ploda, rodnost i pomološke
značajke sorata te promjene fizikalnih i kemijskih svojstava plodova tijekom faze zrenja.
Razlike između sorata, rokova berbe i klimatskih čimbenika s obzirom na fizikalna i kemijska
svojstva statistički su obrađene analizom varijance.
Istraživanjem šećera u plodu šljive utvrđeno je da klimatske prilike značajno utječu na
kakvoću ploda šljive. Tijekom zrenja, koje prati povećanje sume toplinskih jedinica (GDD
vrijednosti), povećava se sadržaj: topljive i ukupne suhe tvari, saharoze, glukoze i ukupnih
šećera, razvoj boje i antocijana. Pod utjecajem klimatskih prilika godine ustanovljene su
razlike u svih sorata u sadržaju i stanju spomenutih svojstava ploda. U obje godine
istraživanja istraživane su sorte postigle punu zrelost uz slične GDD vrijednosti.
Tvrdoća ploda postupno se smanjivala tijekom zrenja u svih istraživanih sorata, a u vrijeme
potpune zrelosti izmjerena je najmanja tvrdoća. U vrijeme potpune zriobe plodovi svih sorata
u obje godine imaju gotovo istu tvrdoću. Boja kožice ploda postupno se sve više razvijala
tijekom zrenja. Za vrijeme zrenja količina antocijana nije se pravilno povećavala, nego je
oscilirala od roka do roka berbe, od sorte do sorte, pa nisu utvrđene određene pravilnosti. Pod
utjecajem klimatskih prilika godine utvrđene su razlike u sadržaju polifenola i
antioksidacijske aktivnosti. Više polifenola i veću antioksidacijsku aktivnost sadržavali su
plodovi u toplijoj i sušnijoj 2012. negoli u 2013. godini. Ustanovljena su velika variranja
između pojedinih rokova berbe. Tijekom zrenja vrijednost DA indeksa mijenjala se dosta
promjenjivo i nije pokazala stabilnu pravilnost, pa između pojedinih rokova berbe nema
opravdanih razlika.
Za utvrđivanje optimalnoga roka berbe mogu se rabiti nedestruktivni kriteriji: boja i GDD, a
od destruktivnih: tvrdoća ploda, topljiva suha tvar i ukupni šećeri.
Sorte ´Toptaste´, ´Tophit´ i ´Haganta´ postižu visoku kakvoću plodova u agroekološkim
uvjetima istočne Hrvatske.In Croatia, plums occupy the third place with respect to the total fruit plantation area and the
volume of fruit production. The plum cultivars represented in Croatian orchards are often
commercially unattractive or sensitive to the PPV and their production is not competitive. A
plum breeding program in Germany has brought to development of several new cultivars of
plums (´Topstar´, ´Toptaste´, ´Haganta´, ´Jojo´, ´Tophit´) that are tolerant to the plum pox
virus and are characterized by more favourable pomological, physical and chemical
properties. Environmental conditions significantly affect the quality of the fruit and it is
necessary to study the adaptability of the new German cultivars to the eastern Croatian agroecological
conditions where a large pool of plums has been traditionally cultivated for
centuries. The pomological, physical and chemical properties of plums can vary significantly
in different cultivation areas as can the subsequent determination of the harvesting period for
certain cultivars. Inadequate harvest-time can cause deterioration (decay) of a high percentage
of fruits in orchards. Unfortunately, there are no universal parameters which would govern
determination of the harvest-time.
The aim of this dissertation is to perform economic evaluation of new cultivars of plums
(´Topstar´, ´Toptaste´, ´Haganta´, ´Jojo´, ´Tophit´) in the eastern Croatian environmental
conditions and to investigate the dynamics of change of the physical and chemical properties
of the fruit during ripening and harvesting in relation to climatic factors.
The research was conducted in the experimental plum orchard of the Agricultural Institute
Osijek, at location ’’Tovljač’’, situated east of Osijek. The experimental orchard was planted
in 2005. The dissertation deals with six plum cultivars: ´Topstar´, ´Toptaste´, ´Haganta´,
´Jojo´, ´Tophit´ and ´Čačanska ljepotica´, grafted on a WaxWa rootstock. The planting density
was 4 × 2.5 m. The growing form was a repaired spindle shape pyramid. The cultivars were
planted in three rows, each row representing a replication. Each row included 4 trees of each
cultivar, which then constituted a block. The blocks were randomized. There was no irrigation
system in the experimental orchard and what was implemented are the standard technological
measures of fertilization, care and protection. The harvest was divided in 4 harvesting periods
and commenced after the fruit had changed its covering colouring. The other three harvesting
sequences were organized every 5-7 days. The research was done within two years. The
measurements included monitoring of the climate conditions, flowering stages, fruit growth
dynamics, yield and the pomological characteristics of the changes on the cultivars regarding
the physical and chemical properties of the fruit during the
variance.
The analysis of the sugar content in the plums has revealed that climate conditions have
significant impact on the quality of fruit. During the ripening, which was accompanied with
an increase in the heat sum (GDD), it came to a rise in the content of soluble and total solids,
sucrose, glucose, total sugars, colour development and anthocyanins. Under the influence of
climate conditions throughout the year, the established differences referred in all cultivars to
both the content and the state of the aforementioned properties of the fruit. In both years of
testing, the researched cultivars reached full maturity with more or less the same GDD values.
With respect to all studied cultivars, the hardness of the fruit was gradually reduced during the
ripening and at the time of full maturity, the minimum hardness was achieved. At the time of
full ripening, the fruits of all the cultivars were characterized by almost the same hardness in
both years. During the ripening, the colour of the fruit skin became progressively more
developed whereas the quantity of anthocyanin was not regularly increased but it fluctuated
with no particular regularity depending on a period of time and a cultivar. Under the influence
of climate conditions throughout the year, there were some differences in the content of
polyphenols and in the antioxidant activity. Comparing the two years, the fruit was featured
by more polyphenols and a more intensive antioxidant activity in the warmer and drier 2012.
Large variations were detected between certain harvest times. During the maturation, the
value of the DA index was changing quite variably and did not show stable regularity while
between certain harvest times, there were no significant differences.
To determine suitable harvest-time, the following non-destructive and destructive criteria can
be used: colour and GDD (non-destructive criteria), and fruit firmness, soluble solid substance
and total sugars (destructive criteria).
Cultivars ´Toptaste´, ´Tophit´ and ´Haganta´ can provide high fruit quality in the agroecological
conditions of eastern Croatia
