Title: Plant bioregulators use in tree fruit production and recent development on fruit set manipulation

Authors: Matej Stopar, Jože Hladnik

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Abstract: Plant bioregulators (PBRs) are used more extensively in tree fruit production than in any other agricultural or horticultural branch. The use of PBRs is essential for efficient annual production of high-quality fruit. Several physiological responses to different PBR substances have been identified and are employed to achieve competitive and profitable fruit production. PBRs are used in fruit production mostly to promote branching, manipulate with flower bud formation, promote or reduce fruit set, prevent preharvest drop, improve fruit appearance, control vegetative growth and to enhance or delay fruit ripening. Due to environmental concerns and the costs of reregistration some PBRs lost their registration in the past, but recently some new physiologically active agents were introduced in fruit production, especially in the area of fruit thinning and retardation of preharvest fruit drop. The use of PBRs in temperate zone tree fruit production with an emphasis on the development in the area of fruit set manipulation is presented in this review.

Key words: PBRs, plant growth regulators, fruit production, plant hormones, thinning agents

Title: Initial and final fruit set of introduced apple cultivars depending on pollenizer

Authors: Milan Lukić, Ivana S. Glišić, Sanja Radičević, Slađana Marić, Nebojša Milošević, Milena Đorđević

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Abstract: The aim of the paper was to underline the impact made by the pollenizer on the level of initial and final fruit set in four commercially important apple cultivars, using them as a base for determining and recommending cultivar combinations suitable for planting within a single orchard. The research was conducted over a three-year period, at the Preljinsko Brdo facility of the Fruit Research Institute, Čačak. The examination included the flowering phenophase, pollen germination in vitro, as well as the initial and final fruit set in cultivars ‘Gala Must’ (S2S5), ‘Red Elstar’ (S3S5), ‘Rajka’ (S5S7) and ‘Topaz’ (S2S5), depending on the pollenizer. The research was conducted in two pollination variants: crossand open pollination. In the cross-pollination variant, each compatible cultivar was used as the pollenizer and the pollinated cultivar (10 combinations) and together with the open pollination variant, a total of 14 combinations were analysed. The average earliest flowering was recorded in ‘Rajka’ (April 8th), whereas the latest average flowering occurred in ‘Red Elstar’ (April 10th). Regarding the flowering time, all tested cultivars overlapped well during the three-year period of examination. In addition, the assessed cultivars had good in vitro pollen germination, ranging from 44.00% (‘Topaz’) to 55.72% (‘Gala Must’). Based on the fruit set, it can be concluded that neither cultivar proved itself as the universal pollenizer for the other cultivars. The highest percentage of the initial (36.95%) and the final (21.38%) fruit set for ‘Gala Must’ was recorded in the open-pollination variant, while the best fructification results for ‘Red Elstar’ occurred in the combination with ‘Topaz’ (41.84% and 23.76%, resp.). The highest values of the initial and final fruit set in ‘Rajka’ (39.26% and 18.81%, resp.) and ‘Topaz’ (38.66% and 26.30%, resp.) were achieved with ‘Gala Must’, i.e. ‘Rajka’ as the pollenizer.

Key words: Malus x domestica, sorta, cultivar, flowering, pollen germination, fruit set

Title: ‘Petra’ new plum (Prunus domestica L.) cultivar from Fruit Research Institute, Čačak

Authors: Nebojša Milošević, Milena Đorđević, Ivana Glišić, Žaklina Karaklajić-Stajić, Milan Lukić, Sanja Radičević, Slađana Marić

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Abstract: This manuscript presents results of comparative study of the most important phenological (flowering and ripening time) and pomological (morphometric, chemical and organoleptic) properties, as well as tree vigour characteristics and productivity of the new plum cultivar ‘Petra’ (‘Stanley’  ‘Opal’), developed at the Fruit Research Institute, Čačak, and standard cultivar ‘Stanley’. Cultivar ‘Petra’ showed late flowering time, similar to cultivar ‘Stanley’ and very late ripening time (beginning of the second decade of September). Tree vigour of this cultivar is medium and cropping potential is large. This cultivar is characterized with medium-large fruit, ovate in shape and dark blue skin colour with heavy bloom. Fruit flesh is yellow, firm, aromatic, contains high amount of soluble solids and sugars, as well as medium amount of total acids. Evaluating organoleptic characteristics, significant consumer acceptance was determined. In the future period ‘Petra’ could be very interesting cultivar for growing in new orchards due to the very late ripening time, good fruit quality and high cropping potential.

Key words: plum, Prunus domestica L., ripening time, fruit, morphometric, chemical and organoleptic properties, yield

Title: Fruit quality and yield of introduced late-ripening sweet cherry (Prunus avium L.) cultivars

Authors: Sanja Radičević, Slađana Marić, Milan Lukić, Nebojša Milošević, Ivana Glišić, Milena Đorđević

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Abstract: Pomological and productive characteristics of four introduced late-ripening sweet cherry cultivars ‘Karina’, ‘Kordia’, ‘Regina’ and ‘Summit’, were studied in the West Serbia region, during the three-year period (2008-2010). The investigation included morphometrical characteristics of fruit (fruit, stone and stalk weight; fruit dimensions height, width and thickness; stalk length; fruit shape index; mesocarp ratio), chemical composition of fruit (soluble solids content; total sugar, inverted sugar and sucrose contents; total acid content; fruit juice pH; sweetness index), and yields per tree and unit area. The highest value of fruit weight was found in ‘Summit’, whereas ‘Kordia’ was characterized with exceptional quality, in terms of chemical composition of fruits. The highest productivity was achieved in ‘Regina’. Generally, the results pointed to the high-quality fruits and high yields of the investigated cultivars, which can be recommended for the commercial sweet cherry orchards in the Republic of Serbia, in order to improve assortment structure, and to extend harvesting season.

Key words: Prunus avium L., cultivar, pomological properties, fruit quality, yield

Title: S-RNase allele identification and incompatibility group assignment in sweet cherry (Prunus avium L.) autochthonous genotypes

Authors: Slađana Marić1, Sanja Radičević, Nebojša Milošević, Milica Fotirić Akšić, Radosav Cerović, Ivana Glišić, Milena Đorđević

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Abstract: Pomological and productive characteristics of four introduced late-ripening sweet cherry cultivars ‘Karina’, ‘Kordia’, ‘Regina’ and ‘Summit’, were studied in the West Serbia region, during the three-year period (2008-2010). The investigation included morphometrical characteristics of fruit (fruit, stone and stalk weight; fruit dimensions height, width and thickness; stalk length; fruit shape index; mesocarp ratio), chemical composition of fruit (soluble solids content; total sugar, inverted sugar and sucrose contents; total acid content; fruit juice pH; sweetness index), and yields per tree and unit area. The highest value of fruit weight was found in ‘Summit’, whereas ‘Kordia’ was characterized with exceptional quality, in terms of chemical composition of fruits. The highest productivity was achieved in ‘Regina’. Generally, the results pointed to the high-quality fruits and high yields of the investigated cultivars, which can be recommended for the commercial sweet cherry orchards in the Republic of Serbia, in order to improve assortment structure, and to extend harvesting season.

Key words: : Prunus avium L., cultivar, pomological properties, fruit quality, yield