ASSESSMENT OF SOME VEGETATIVE POMOLOGICAL PARAMETERS OF SOUR CHERRY CULTIVARS UNDER NORD – EAST ROMANIAN CONDITIONS

The paper introduces aspects about the influence of environmental factors in 2019 – 2021 period on vegetative parameters of some sour cherry cvs. Analysing the time window between April and July (for each of the three years of study), 2019 and 2020 recorded a precipitations deficit of -71.6 mm (2019) and -86.0 mm (in 2020) in comparison with 270.0 mm representing the multiannual sum for this period, while 2021 recorded normal quantities of precipitations of 272.0 mm. The values of the trunk’s section area based on the average of three years of study were between 4.6 cm2 (ʹErdi Ipariʹ cv.) and 16.3 cm2 (ʹErdi Biborʹ cv.). The highest values for the volume of the crown were recorded in ʹDukatʹ (3.23 m3/tree) and ʹErdi Kordiʹ (2.88 m3/tree) cvs. while the lowest values were recorded in ʹErdi Biborʹ (2.19 m3/tree), ʹErdi Ipariʹ (1.56 m3/tree) and ʹErdi Kedvesʹ (1.55 m3/tree) cvs. The density of the trees’ crown had values between 4.74 cm2/m3 (ʹErdi Ipariʹ cv.) and 12.13 cm2/m3 (ʹErdi Kedvesʹ cv.). The estimates of the young shoots per tree and their average length over the three years of study have shown values superior than control for ʹErdi Biborʹ (41 young shoots with 70.5 cm), ʹErdi Kordiʹ (32 young shoots with 63 cm) and ʹDukatʹ (18 young shoots with 85.4 cm) cvs.

FRUIT QUALITY OF NEW INTRODUCED PLUM CULTIVARS UNDER THE CONDITIONS OF BULGARIA

Prunus domestica L. is one of the most commonly grown fruit species in Bulgaria due to its high ecological adaptation and multiple ways of fruit marketing. Fruit quality is associated with attributes such as appearance, texture, taste and colour. Breeding and new cvs. introduction are in constant search for cultivars with better fruit quality that would answer the increasing consumer requirements. In 2013 the Romanian plum cvs. ‘Pitestean’, ‘Roman’, ‘Romanta’, ‘Carpatin’ and ‘Tita’ were introduced in Bulgaria and planted in a collection orchard at the Fruit Growing Institute, Plovdiv. The study was conducted in the period 2016-2021. It aimed to evaluate the fruit quality when the cultivars are grown under the agro-environmental conditions of the region. For obtaining this objective, fruit weight, fruit flesh firmness, TSS (°Brix), skin colour with and without wax bloom and fruit flesh colour were measured. For evaluating consumer acceptance, a sensory analysis was performed. ‘Roman’ had the largest fruits with an average fruit weight of 46.66 g and the highest TSS content – 18.2°Brix. There were significant differences in the colour parameters L*, a*, b*, Chroma and Hue between the cultivars and the wax bloom had a significant effect on colour parameters. All fruits were appreciated by the testing panel of consumers and their taste qualities were evaluated as good and very good.

THE INFLUENCE OF DIFFERENT PHYTOPROTECTION SYSTEMS ON ENTOMOFAGE FAUNA IN APPLE PLANTATION

The paper presents data on the diversity of entomophagous fauna in an ecologically managed apple plantation, as well as aspects regarding the differences found in the structure of the entomophagous complex in three variants of phytoprotection technologies: "Ecological", "Biotechnical" and "Chemical standard". The study was carried out during the years 2019-2020, at the Research Institute for Fruit Growing Pitesti, in a plot aged 12 years. The evaluations were performed both in the field, visually and in the laboratory, at binocular magnifier. As a result of this study, a number of 6 species of predatory insects were identified: Chrysopa carnea, Coccinella septempunctata, Adalia decempunctata, Anthocoris sp., Phytoseiulus persimilis and Aphidoletes aphidimyza, were mainly from the Orders Mesostigmata, Coleoptera, Neuroptera, Diptera and Hemiptera.

PLUM VARIETIES USED AS PARENTS IN ROMANIAN BREEDING PROGRAM

There are about three thousand varieties belonging to Prunus domestica available at present worldwide that can be used as genitors in plum breeding activity. An analysis of the pedigrees of plum cvs. developed in Romanian breeding programs shows that the most are descended from ‘Tuleu gras’, ‘Renclod Althan’, ‘Anna Späth’, ‘Stanley’ and ‘Early Rivers’, called 'ancestors'. That means the majority of plum cvs. have at least one of the ancestors as parent or grandparent. For those 40 plum cvs. registered in Romania in 60 years an increased number of crosses with these 'ancestors' has led to what we call 'inbreeding'. According to data presented in this paper, ‘Tuleu gras’ cv. was the most frequently used parent in the cross combinations, giving origin to 23 cvs. Among the other frequently used genitors were: ‘Renclod Althan’ (7 cvs.), ‘Anna Späth’ (3 cvs.) and ‘Stanley’ (1 cv.). Many of the cultivars – 32 altogether (80%) have originated from hybridization, whereas 4 cvs. have originated from open pollination, others 3 cvs. from mutagenesis and 1 cv. from clonal selection. The goal of this work is to measure genetic diversity presently use in Romanian plum breeding. Pedigrees of each cv. were used to study the genetic contributions of ancestor. Of the 40 cvs. analyzed, 33 had an inbreeding coefficient other than zero. The overall mean inbreeding coefficient was 0.419 for all cvs., where their parentages were known. For cvs. with unknown parentage (nonrelated with known parentage) the inbreeding coefficient is zero. The mean coefficient of coancestry of 40 plum cvs. are 0.081 with ‘Tuleu gras’ cv., 0.019 with ‘Renclod Althan’ and ‘Anna Späth’ cvs., 0.017 with ‘Early Rivers’ cv., 0.014 with ‘d’Agen’ and ‘Renclod Violet’ cvs. and 0.005 with Stanley cv. In conclusion, plum breeders have worked with populations of greatly reduced genetic diversity and this strategy becomes a problem because it leads to genetic impoverishment, and, also, the loss of the genetic resistance to different diseases.

FRUIT PHYSICO-CHEMICAL QUALITY PARAMETERS OF NEW INTRODUCED APPLE CULTIVARS

The apple fruit is the second most frequently consumed, after bananas and some quality characteristics like size, gloss, color, and aroma influenced directly the flesh consumption. In this study, the external (weight, size, skin colour) and internal (firmness, total soluble solids, acidity, pH) fruit quality attributes were measured experimentally before the storage, using well defined techniques. 'Corelita', 'Coreal', 'Corealor', 'Coredova', 'Corejuno', 'Coretard', 'Coreagat', 'Coreor' and 'Coreprim' cultivars were registered, in the last 15 years, by Practical Scientific Institute of Horticulture and Food Technologies Chișinău, Republic of Moldova, as scab resistant varieties. The orchard trial was established at the Research Institute for Fruit Growing Pitesti, Romania in the spring 2014 on MM106 rootstock, at the spacing of 3.5 x 2 m and fruit samples were analyzed in 2019, 2020 and 2021 seasons. All studied cultivars were harvested before 'Florina' cv., used as control. Fruit weight was quite variable among genotypes, between 115.15 g at 'Coreal' cv. and 212.41 g at 'Corejuno', and most of the cultivars had smaller fruits than 'Florina' cv. Firmness and total soluble solids varied from 70.5 to 82.61 N and 12.77 to 16.77%Brix. The Hunter color values L, a, b, were found to be in the range of 46.12 to 56.76, - 6.46 to 14, 13.75 to 23.72, respectively. The data about the external and internal fruit quality of new Moldavian scab resistant apple cultivars are useful for growers, in order to introduce in the new orchards only cultivars with high quality fruits.

MATING DISRUPTION OF GRAPHOLITA MOLESTA BUSCK. TO IMPROVE QUALITY AND HEALTHY OF PEACH FRUITS

In Bulgarian fruit growing agriculture mainly chemical plant protection is applied. Applications with organophosphates and pyrethroids are carried out to control the economically most important peach pest - the oriental fruit moth (Grapholita molesta Busck.). Annually during the vegetation season 7-8 insecticide treatments are applied. This leads to contamination of fruit products and the environment, which is a prerequisite for seeking other approaches. Regarding to fruit moth, sex pheromones are one of the most widely used environmental control methods, but they are most commonly used in apples. Their introduction in the monitoring of the main peach pest can lead to a reduction of chemical treatments and production with less pesticide residues. A promising direction is the use of pheromones to control the pests through sexual disorientation of males. The trial of mating disruption in the present study were carried out with ISOMATE® OFM TT dispensers in 0.9 ha peach orchard in 2020 and 2021. Pheromone traps type "Delta" of the Hungarian company CSALOMON® were used. The ISOMATE OFM TT dispensers, installed before the first flight of OFM at the rate of 250 units per ha, efficiently reduced fruit damages - down to 0.1-0.2% at harvest. In the reference orchard with 6 insecticide treatment against OFM, the damages reached 3.0-3.6%. The results indicate that mating disruption for control of Grapholita molesta Busck. can be used in production of quality and healthy peach fruits.

INFLUENCE OF LOW VIGOUR ROOTSTOCKS ON GROWTH AND FRUITING PROCESS OF ‘REGINA’ CULTIVAR

The aim of this paper was to study the influence of low vigor rootstocks on the 'Regina' cherry cultivar. The study was conducted at Research Institute for Fruit Growing Pitesti, Arges county, Romania between 2019 and 2021. A bifactorial experiment was set up, with A factor-the rootstock ('Gisela 3', 'Gisela 5', 'Gisela 12' and 'Weigi 2') and B factor-the study year (2019, 2020 and 2021). Fruiting and vegetative growth data (fruit production, the trunck cross-section area-TCSA, the annual increase of TCSA, the productivity index and the ratio between the fruit production and the annual increase of TCSA), as well as fruit quality data (fruit mass, firmness, pH, total soluble content, chromatic coordinates of epicarp color and chlorophyll fluorescence) were collected. 'Gisela 5' rootstock recorded the highest value of TCSA annual increase (11.46 kg/cm2) and had also the highest cromatic coordinates values: colour brightness (25.68), red pigment (15.61) and yellow content (4.12).The highest vigor of the cultivar 'Regina' was observed in 'Weigi 2' rootstock variant (with an TCSA value of 44.71 cm2), given that 'Weigi 2' TCSA annual increase was similar to 'Gisela 5'. 'Gisela 3' rootstock stood out for its fruit highest pH (3.97), fruit yield (13.51 t/ha), lowest vigor (TCSA=24.19 cm2), smallest annual TCSA increase (6.11 cm2), highest productivity index 0.219 kg/cm2) and highest fruit production to annual TCSA increase ratio (1.79 kg/cm2). Taking into account climatic accidents that marked the spring of 2021, on the average of the study years, the cultivar 'Regina' grafted on the rootstock 'Gisela 12' was distinguished by fruit weight (10.02 g), firmness (66.53 units HPE Bareiss) and TSS (16.03°Brix) on the background of the lowest fruit yield. A negative very signifficant correlation between fruit yield and fruit quality traits (weight, firmness and total soluble solids) was found.

STUDY OF GENETIC DIVERSITY AND ANALYSIS OF THE DEGREE OF SIMILARITY IN SOME APPLE AND PLUM VARIETIES USING RAPD MARKERS

Molecular evaluation of germplasm is an important step in breeding programs, and the application of molecular biological techniques has led to important results in terms of both within- and between-species variability of traits. The RAPD technique has been successfully used to reveal allelic polymorphism as well as to measure genetic similarity. In this study, the genetic diversity of 25 genotypes and cultivars for apple species and 26 genotypes and cultivars for plum species was assessed with six RAPD markers. All these cultivars belong to the ex situ collection of apple and the ex situ collection of plum at the Research Institute for Fruit Growing Pitesti. The average number of amplified bands was 19.2 for apple and 17.66 for plum. Statistical analysis of intraspecific allelic polymorphism was expressed using the PIC (Polymorphic Information Content) index, which takes into account the allelic frequency. Two statistical indices were used to quantify genetic diversity: the Shannon index and the Simpson index. The degree of similarity between varieties was analyzed using the NTSYSpc version 2.1. Following RAPD analyses, the allele sizes of the analyzed varieties were within the range quoted in the literature, the genetic profiles of the studied varieties suggesting a medium to high genetic diversity, except for markers OPBC-04 and OPBB-05 for plum species, which expressed a high genetic diversity. Genetic distances calculated based on polymorphism of migrated bands in agarose gel confirmed the known genealogies of the apple and plum varieties studied. Thus, the smallest genetic distance for apple species was found between 'Jonagold' and 'Golden Delicious', 'Pionier' and 'Rustic', 'Jonathan' and 'Idared', 'Wagener Premiat' and 'Granny Smith', 'Remar' and 'Aura', 'Romus 3' and 'Rome Beauty', and the largest between Malus floribunda and the other genotypes studied. In plum, the smallest genetic distance was found between 'Dani' and 'Tita', 'Roman' and 'Tuleu gras', 'Dara' and 'Haganta', 'Romanța' and 'Stanley', 'Anna Spath' and 'Renclod Violet', and the largest between 'Lama', 'Black Diamond' and the other genotypes studied.

INCIDENCE OF TBRV AND ArMV VIRUSES IN NEW CHERRY PLANTATIONS FROM AREA OF ROMANIA

Viral diseases can influence negatively a good evolution of cherry plantations. Two of the viral diseases that attack this species are caused by the ArMV virus, which spreads by multiplying the infected propagating material, by seed and nematodes, and by the TBRV virus, which spreads by multiplying the infected material and nematodes. In order to study the incidence of the two viruses, 10 cherry plantations located in the south of the country were evaluated, in the district of Argeș, Dolj, Ialomița, Ilfov, Călărași, Dâmbovița, Buzău. The planting material used to set up the plantations was both from Romania and from an external source: the Netherlands, Greece, Italy. Viral evaluation performed visually and serologically by DAS-ELISA technique, identified viral infections in 2 of the 10 plantations. In one plantation, TBRV was identified in 20% of the tested samples and in the second, ArMV viruses were identified in 20% of the samples and TBRV in 5% of the samples.

IN VITRO PROPAGATION OF PLUM ROOTSTOCK DOCERA 6

This paper describes research on the application of tissue culture techniques to the micropropagation of interspecific rootstock ʹDocera 6ʹ. The experimental work was carried out in the period 2017-2018, in the in vitro propagation laboratory of the Fruit Growing Institute Plovdiv. Аxillary buds were employed as initial explantеs in two different seasons (March-May; September-October). The action of the mineral medium was studied in the multiplication stage. The best result was obtained on LS medium included BAP 0.5 mg/l and IAA 0.05 mg/l. Тhe obtained average multiplication rate is 3.08. The concentration of auxin applied to the basal medium influence the quality of the root system Treatment with high concentrations of IBA added to the rooting medium gives the best results (V5). Тhe influence of the season on growth and development of micropropagated ʹDocera 6ʹ rootstock during ex vitro acclimatization is also part of our research. The spring acclimatization gives better results than the autumn.