EFFECTS OF DIFFERENT TIMES OF SUMMER PRUNING TO PRODUCTIVITY AND FRUITS QUALITY OF APPLE CULTIVAR GALA BROOKFIELD

Apple (Malus × domestica Borkh.) is the most important of the deciduous tree fruits in Serbia in last decade, with annual production of about 450.000 tonnes. The cultivar Gala is one of the most represented cultivar in orchard. Serious problem in increase of profitability of apple producers in Serbia is low fruits quality of this cultivar, especially expressed in decrease of surface blushing. Summer pruning, before fruits harvest is one of possiability to improved their quality. In this paper the aim of examination was to determine effects of three different times of summer pruning to productivity and fruits quality of cultivar Gala Brookfield. The trees pruning four weeks before harvest (treatment 1) had significantly bigger fruits (138.6 g) with higher diameter (68.4 mm), percent of surface blushing (66.3 %) and content of soluble solid (12.9° Brix) according to other treatments. The trees pruning two weeks before pruning (treatment 3) had the lowest fruits quality in terms of fruits mass (109.5 g), intensity of surface blushing (1.6) and content of soluble solid  (11.4° Brix). Mainly, the highest values of fruits quality in all treatments had fruits in upper part of trees. Trees in treatment 1 and treatment 2 (pruning threes weeks before harvest) had fruits with more than 65% of surface blushing and without of sunburn demage

PRODUCTIVITY OF EARLY AND MEDIUM EARLY APRICOT CULTIVARS IN THE BELGRADE AREA

Characteristics of productivity and growth (yield per tree, trunk cross-sectional area, yield efficiency and fruit weight) were studied in 40 apricot cultivars of early and medium early maturity in the Belgrade area during the six-year period (2009 – 2014). The cultivar ‘Hungarian Best’ was used as a control for comparison. The period of study was divided to initial bearing (age of trees three and four years) and full bearing (age of trees from five to eight years). Significant differences in yield between cultivars and years were found. Average yield in the period of initial bearing ranged from 0.3 to 11.3 kg per tree, and in the period of full bearing from 5.6 to 24.8 kg per tree. Compared with the control cultivar, significantly higher yield was obtained in 17 cultivars. Adverse weatherconditions resulted in significant reduction of yield in two out of six years of study. Cumulative yield efficiency varied from 0.17 to 0.87 kg/cm2 and in 19 cultivars it was significantly higher compared with the control cultivar. Fruit weight ranged from 27.7 to 80.1 g. Compared with control, fruit weight was significantly higher in nine cultivars, and significantly lower in 11 cultivars

The effects of the parents’ genotype on susceptibility to leaf curl (Taphrina deformans (Berk.) Tul) of vineyard peach hybrid seedlings

Leaf curl is one of the peach diseases with the most economically important impact, because very strong infection can cause total defoliation. Susceptibility to a leaf curl was examined from the period 1994-1998 in a collection of selected vineyard peach genotypes and newly peach and nectarine cultivars. Selected low susceptible genotypes (vineyard peach GR/65/87 and processing peach Villa Ada) were used in cross-pollination with differently susceptible genotypes. The process produced more than 250 seedlings of F1 progeny from few combinations of the parents. Susceptibility of hybrid seedlings to the leaf curl pathogen was investigated several years in the open field, without application of pesticide. More types of inheritance of examined characteristic were determinate in the progenies from different combinations of the parents. The results agree with polygenic inheritance.

INFLUENCE OF VEGETATIVE ROOTSTOCKS ON BIOLOGICAL AND PRODUCTION PROPERTIES OF SWEET CHERRY CULTIVAR ‘REGINA’ IN EARLY BEARING PERIOD

The study researched the influence of four vegetative rootstocks on a biological and production properties of sweet cherry cultivar ‘Regina’. The study was carried out during fourth and fifth growing years at an orchard located at the experimental estate “Radmilovac” of the Faculty of Agriculture in Belgrade. Cultivar ‘Regina’ was grafted on the following rootstocks: ‘Gisela 6’, ‘Ma×Ma 14’, ‘Colt’ and ‘Oblačinska cherry’, while trees grafted on P. mahaleb used like a control. The highest yield had trees grafted on rootstock ‘Gisela 6’ (6.5 kg), while the smallest yield had trees grafted on seedlings of P. mahaleb (1.4 kg). Cultivar ‘Regina’ had the highest number of sper fruiting branches on ‘Colt’ (367.2) and the smallest number was recorded on P. mahaleb (154.8), while number of lateral fruiting branches on trees of cultivar ‘Regina’ was between 91.6 (‘MaxMa 14’) and 42.2 (‘Oblačinska cherry’). The highest content of soluble solid matter and sweetness in fruit were on the trees grafted on P. mahaleb

CHARACTERISTICS OF FRUITING SHOOTS OF SOME PEACH AND NECTARINE CULTIVARS

Morphological characteristics of fruiting shoots: length, diameter, internode length, length of the basal part without flower buds, number of flower buds (per shoot, node and 1 m of shoot length) were studied in 12 peach and 12 nectarine cultivars. The study was conducted at the Experimental farm “Radmilovac” of the Faculty of Agriculture in Belgrade during the two–year period (2016-2017). Control cultivar for peaches was ‘Redhaven’, and for nectarines ‘Stark Redgold’. For all studied traits statistically significant differences between cultivars were found. The average length of shoots varied from 62.4 to 76.8 cm, diameter from 5.9 to 8.0 mm, and internode length from 2.45 to 3.00 cm. The length of basal part of a shoot without flower buds was on average lower in nectarines (3.9 cm) than in peaches (9.1 cm). Peach cultivar ‘Tardibelle’ is characterized by the longest basal part of a shoot without flower buds (22.2 cm). All studied peach cultivars are characterized by lower flower bud density compared to control (‘Redhaven’). In nectarines, most of the studied cultivars had flower bud density similar to control (‘Stark Redgold’). Cultivars with higher flower bud density such as peaches: ‘Redhaven’, ‘Maria Marta’, ‘Autumn Glo’, and nectarines ‘Rita Star’, ‘Maria Carla’, ‘Orion’ require severe pruning in order to obtain better fruit size. On the other hand, cultivars with lower flower bud density e.g. ‘Tardibelle’, ‘Flavorcrest’, ‘Royal Glory’, ‘Bolero’, ‘Maria Lucia’ should be pruned slightly in order to obtain higher yield

Isoenzyme polymorphism of almond genotypes selected in the region of northern Serbia

Isoenzyme polymorphism was studied in 20 almond (Prunus dulcis [Mill.] D. A. Webb) genotypes selected from seedling populations of unknown almond cultivars in the region of northern Serbia (Vojvodina). Fourteen enzyme systems were studied using the method of vertical polyacrylamide gel electrophoresis. Ten systems were polymorphic in twelve loci. This polymorphism allowed unique identification of all studied genotypes. The most useful enzyme for analysis of almond genetic variability was menadione reductase. Polymorphism identified for alkaline phosphatase, formate dehydrogenase, glutamate dehydrogenase, malic enzyme, and menadione reductase was reported for the first time in almond. Cluster analysis was used to construct a dendrogram on which five clusters with different number of genotypes could be identified

INFLUENCE OF SPRING FROST ON APPLE FLOWER BUDS AT VARIOUS DEVELOPMENTAL STAGES

Spring frost often reduces the yield because of damaged flowers. Spring frost is a dangerous climatic hazard that can be responsible for yield loses to orchard trees. Frost damage is highly dependent on the stage of development of the flower buds. Flowers buds samples were collected from ‘Granny Smith’, ‘Golden Delicious Rainders’ and ‘Gala Schniga’ apple cultivars at different flower buds stages from BBCH 59 (most flowers with petals forming a hollow ball) to BBCH 65 (full bloom on trees), two days after frost that occurred on the morning at 5:00-7:00 of March 31, 2017 when the temperature dropped to -1.5 to -3.3°C in the apple orchard of company Pollino Agrar near Fruška gora mountain. Pistils in flower buds samples at a hollow ball stage to full bloom were examined individually and classified as dead or alive based on tissue browning. The highest damage on flowers was recorded to cultivar ‘Gala Schniga’ (75.4%) and the lowest to cultivar ‘Golden Delicious Rainders’. Cultivar ‘Gala Schniga’ had more than 90% of damaged king flowers. Our results showed that the spring frost damage of pistils was variable according to stages of flower bud development and genotypes

Características da biologia reprodutiva que afetam a produtividade de cereja ácida

The objective of this work was to evaluate variability in reproductive biology traits and the correlation between them in genotypes of 'Oblačinska' sour cherry (Prunus cerasus). High genetic diversity was found in the 41 evaluated genotypes, and significant differences were observed among them for all studied traits: flowering time, pollen germination, number of fruiting branches, production of flower and fruit, number of flowers per bud, fruit set, and limb yield efficiency. The number of fruiting branches significantly influenced the number of flower and fruit, fruit set, and yield efficiency. In addition to number of fruiting branches, yield efficiency was positively correlated with fruit set and production of flower and fruit. Results from principal component analysis suggested a reduction of the reproductive biology factors affecting yield to four main characters: number and structure of fruiting branches, flowering time, and pollen germination. Knowledge of the reproductive biology of the 'Oblačinska' genotypes can be used to select the appropriate ones to be grown or used as parents in breeding programs. In this sense, genotypes II/2, III/9, III/13, and III/14 have very good flower production and satisfactory pollen germination.O objetivo deste trabalho foi avaliar a variabilidade de características da biologia reprodutiva e a correlação entre elas, em genótipos da cereja ácida (Prunus cerasus) 'Oblačinska'. Verificou-se alta diversidade genética nos 41 genótipos avaliados, e foram observadas diferenças significativas entre eles, para todas as características estudadas: época de florescimento, germinação de pólen, número de ramos frutíferos, produção de flores e frutos, número de flores por botão, formação de frutos e eficiência de produção dos ramos. O número de ramos frutíferos influenciou significativamente o número de flores e frutos, a formação de frutos e a eficiência produtiva. Além do número de ramos frutíferos, a eficiência produtiva correlacionou-se positivamente com o pegamento de frutos e a produção de flores e frutos. Os resultados da análise de componentes principais sugerem a redução dos fatores de biologia reprodutiva que afetam a produtividade a quatro características principais: número e estrutura dos ramos frutíferos, tempo de florescimento e germinação de pólen. O conhecimento da biologia floral dos genótipos 'Oblačinska' pode ser útil para a escolha dos mais apropriados para plantio ou uso como parentais em programas de melhoramento. Neste sentido, os genótipos II/2, III/9, III/13 e III/14 apresentam produção de flores muito boa e germinação de pólen satisfatória

Ispitivanje auto-(in)kompatibilnosti genotipova badema (Prunus amygdalus batsch) selekcionisanih na Slankamenačkom bregu

Due to the importance of obtaining almond cultivars adapted to the agroecological conditions of Serbia, in the period 2005-2006 pollen viability and self-(in)compatibility in 19 almond genotypes selected from the seedling population on Slankamen hill, were studied. All analyzed almond genotypes had good (50-70%) or high (over 70%) pollen germination. The study of self-(in)compatibility was done by monitoring of the fruit set in the field and observing self-pollen growth by fluorescence microscopy. Self-incompatibility was confirmed in all the 19 genotypes by both methods. Pollen tube penetration was stopped mostly at the upper third of the style of all genotypes, with characteristic irregularities.U cilju stvaranja sorti badema prilagođenih agro-ekološkim uslovima Srbije u periodu 2005.-2006. godine proučavana je klijavost polena i auto (in)kompatibilnost 19 genotipova badema odabranih iz populacije sejanaca na Slankamenačkom bregu. Svi ispitivani genotipovi badema imali su dobru (50-70- %) ili visoku klijavost polena (preko 70%). Ispitivanja auto (in)kompatibilnosti su obavljena praćenjem zametanja u poljskim uslovima i metodom fluorescentne mikroskopije. Auto inkompatibilnost je u oba slučaja bila izražena kod svih 19 genotipova. Kod svih genotipova polenove cevčice su zaustavljale rast najdalje u gornjoj trećini stubića uz karakteristične petlje, zadebljanja i krivudanja

Karakteristike rodnih grančica sorti evropske šljive (Prunus domestica L.) i japanske šljive (Prunus salicina lindl.)

Morphological properties of fruit bearing shoots: length, number of flower buds and vegetative buds and their ratio were studied in 11 cultivars of European plum and 11 cultivars of Japanese plum during a two-year period. Fruit bearing shoots were divided into two groups: long (shoots) and short (spurs). For all studied traits, statistically significant differences between plum cultivars were found. Japanese plums had lesser thickness and shorter internodes of shoots in relation to European plums. They also had a significantly higher number of flower buds both on shoots and spurs. Based on obtained results, recommendations for pruning can be made. Cultivars with a higher number of flower buds per 1-m length and in relation to vegetative buds, like most varieties of Japanese plum and some varieties of European plum ('Stanley', 'Topper', 'Top', 'Topking'), require severe pruning. On the other hand, cultivars with lower density of flower buds, such as 'Čačanska rana' and 'Golden Plum', can be pruned slightly.Kod 11 sorti evropske šljive i 11 sorti japanske šljive u periodu od dve godine proučavane su morfološke osobine rodnih grančica: dužina, broj cvetnih i vegetativnih pupoljaka i njihov odnos. Rodne grančice podeljene su na dve grupe: duge i kratke. Japanske sorte šljive su imale manju debljinu i kraće internodije na dugim rodnim grančicama u odnosu na evropske sorte šljive. One su takođe imale znatno veći broj cvetnih pupoljaka kako na dugim, tako i na kratkim rodnim grančicama. Na osnovu dobijenih rezultata mogu se dati preporuke za izvođenje rezidbe. Sorte sa većim brojem cvetnih pupoljaka po 1 m dužine i u odnosu na vegetativne pupoljke, kao što je slučaj kod većine sorti japanske šljive i nekih sorti evropske šljive (Stanley, Čačanska lepotica, Toper, Top, Topking) zahtevaju jaču rezidbu. Sa druge strane, kod sorti sa manjom gustinom cvetnih pupoljaka kao što su Čačanska rana i Golden Plum, potrebno je primeniti rezidbu slabijeg intenziteta