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Open access

Inger Hjalmarsson

Abstract

This article reviews the history of plum cultivation and cultivars in Sweden with the aim to describe important heirloom cultivars and to explain how they are conserved in the Swedish National Gene Bank. Commercial plum production in Sweden started around 1890 and was initially in part based on small-fruited local cultivars grown on their own roots. Along with the development of a modern Swedish nursery industry and experimental research the use of grafted trees grew in importance. In the mid-1950s, the yearly plum production in Sweden was estimated to be approximately 2000 tonnes. Since the mid-1980s, production has declined and it is now only about 250 tonnes per year. The work to safeguard heirloom cultivars began with a national inventory in 2005 and since 2012, so-called mandate cultivars have been planted in the Swedish National Gene Bank at Alnarp. Today 45 plum cultivars are preserved with two trees in the gene bank at Alnarp and two trees in local clonal archives.

Open access

Juozas Lanauskas, Darius Kviklys, Nobertas Uselis and Loreta Buskienė

Abstract

Twenty plum cultivars on Myrobalan (Prunus cerasifera Ehrh.) seedling rootstock were tested in 2012–2017 at the Institute of Horticulture of the Lithuanian Research Centre for Agriculture and Forestry. Plum trees were spaced at 4.5 × 2.5 m and trained as spindles. Orchard floor management included frequent mowing of grass in the alleyways with herbicide strips along tree rows. ‘Duke of Edinburgh’, ‘Kijevas Vēlā’, ‘Dąbrowicka Prune’, ‘Čačanska Najbolje’, ‘and ‘Štaro Vengrinė’ cultivars were the most vigorous plum trees at the end of 6th year. Their trunk diameter achieved 92–96 mm. ‘Valor’, ‘Queen Victoria’, ‘Herman’, ‘Čačanska Najbolje’, ‘Favorita del Sultano’, ‘Ave’, and ‘Jubileum’ cultivars had the lowest trunk diameter — 72–78 mm. The highest cumulative yield of four fruiting years was recorded for ‘Kometa’ and ‘Violeta’ cultivars, respectively, 43.0 and 46.5 kg/tree. ‘Favorita del Sultano’, ‘Rausvė’, and ‘Kijevas Vēlā’ produced the largest fruits — 52–60 g. The smallest fruit occurred on ‘Dąbrowicka Prune’ and ‘Herman’ cultivars, respectively, 22 and 25 g. ‘Dąbrowicka Prune’ had the highest soluble solids content (SSC) — 19.5%. The least SSC was recorded in ‘Kometa’, ‘Violeta’ and ‘Herman’ fruits — 10.6–11.8%. ‘Renklod Rannij Doneckij’, ‘Čačanska Najbolje’, and ‘Valor’ cultivars had the highest fruit flesh firmness.

Open access

Dzintra Dēķena, Ina Alsiņa, Valda Laugale and Kersti Kahu

Abstract

The selection of appropriate rootstock is the main precondition for obtaining a high yielding and sustainable plum orchard. In the Northern climate, plum overwintering is especially important, where winter hardiness of flower buds is one of indicators. This investigation was carried out during three wintering periods (2010–2013) at the Institute of Horticulture in Pūre (Latvia) and the Polli Horticultural Research Centre (Estonia), in orchards planted in 2001. The aim of the investigation was to evaluate the influence of different rootstocks on the viability of flower buds during winter for two plum cultivars in two growing regions. European plum ‘Victoria’ and hybrid plum ‘Kubanskaya Kometa’ grafted on eight clonal and eight seedling rootstocks were used in the investigation. Bud samples were taken two times during winter: end of January and end of March. The viability of flower buds and flowering intensity were determined in the laboratory. The viability was determined as dehydrogenase activity using triphenyl tetrazole chloride (0.5%), where in living cells the colourless substance due to enzymatic activity turns into a brightly coloured product — formasan. The optical density of colour was determined with a spectrophotometer at 485 nm. Both cultivars ‘Kubanskaya Kometa’ and ‘Victoria’ had higher flower bud viability in Polli compare to Pūre. In both growing regions, the highest activity of dehydrogenases for cultivar ‘Kubanskaya Kometa’ was on rootstocks ‘Myrobalan’, ‘St. Julien INRA 2’, ‘Wangenheims Zwetsche’ and for cultivar ‘Victoria’ — on rootstocks ‘Ackermann’, ‘Brompton’ seedlings, and ‘St. Julien d’ Orleans’. The dehydrogenase activity of in flower buds had a tendency to decrease during winter.

Open access

Ingrida Mazeikiene, Darius Kviklys, Jurate Brone Siksnianiene, Dainius Zinkus and Vidmantas Stanys

Abstract

Prunus necrotic ring spot ilarvirus (PNRSV) and Apple chlorotic leaf spot trichovirus (ACLSV) are common in plum orchards. The aim of the study was to obtain virus-free planting material of Prunus domestica L. by chemotherapy in vitro. Ribavirin at concentrations of 10 to 50 mg·l−1 was added to Murashige–Skoog (MS) nutrition medium for virus eradication from microshoots. After a two-week period of chemotherapy, meristems were subcultured monthly on MS medium and proliferation index of shoots was estimated. Microshoots were retested by reverse transcription polymerase chain reaction for presence of virus. At lowest concentrations of 10 mg·l−1 ribavirin was entirely ineffective for ACLSV and 10 to 30 mg·l−1 was ineffective for PNRSV elimination. Ribavirin concentrations of 40 and 50 mg·l−1 destroyed both pathogens. However, at higher concentrations of 40 and 50 mg·l−1 ribavirin exhibited some signs of phytotoxicity on microshoots in the first sub-cultivation period. In order to test the genetic stability of the microplants after chemotherapy the amplified fragment length polymorphism (AFLP) method was applied. Plant genome stability in ‘Magna Glauca’ at concentrations of 40 mg·l−1 was damaged, as the presence of polymorphic AFLP markers were observed.

Open access

Dzintra Dēķena, Jānis Lepsis, Ina Alsiņa, Līga Lepse and Kersti Kahu

Abstract

The issue of the influence of rootstock on winter-hardiness of plum (Prunus × rossica Erem.) tree flower buds in the Baltic region is becoming important. The choice of rootstock is the main precondition for obtaining a high yielding and sustainable plum orchard. Freezing of flower buds is one of the most significant damages in winter for stone fruits. The aim of the investigation was to determine the relationship between concentration of dry matter and reducing sugars in annual shoots during winter and wintering ability of trees. The dynamics of reducing sugar concentration in one-year-old shoots during winter was investigated during two successive seasons in two locations. Orchards were planted in 2001 in Latvia and in Estonia. The well-known plum cultivar ‘Kubanskaya Kometa’ (Prunus rossica Erem.) was grafted on eight clonal rootstocks (‘St. Julien A’, ‘Brompton’, ‘Ackermann’, ‘Pixy’, GF8/1, G5/22, GF655/2, and ‘Hamyra’) and eight generative propagated rootstocks (‘St. Julien INRA 2’, ‘St. Julien d’Orleans’, ‘St. Julien Noir’, ‘Brompton’, ‘Wangenheims Zwetsche’, ‘St. Julien Wädenswill’, ‘Myrobalan’ and Prunus cerasifera var. divaricate). Shoot samples were harvested two times during winter — at the end of January and at the end of March. Dry matter concentration (mg·g−1) and the concentration of reducing sugars (mg·g−1 DM) by Fehling’s solution method was determined. Tree flowering intensity was scored using a scale from 1 to 5, where 1 = no flowers and 5 = abundant flowering. Dry matter concentration in plum shoots varied among rootstocks, years and growing location. In Pūre, Latvia, the largest differences in dry matter concentration were found for trees grafted on ‘St. Julien INRA2’ (in 2011–2012) and ‘Brompton’ cuttings (in 2012–2013) but in Polli, Estonia for trees grafted on G5/22 (in 2011–2012) and ‘Myrobalan’ (in 2012–2013). One of the most stable rootstock/graft combinations in the trial when GF655/2 was used as rootstock, where dry matter concentration was between 491 and 525 mg·g−1, and reducing sugars between 37.5–49.2 mg·g−1, and flowering intensity between 2.5 and 4.

Open access

Ilze Grāvīte, Edīte Kaufmane, Laila Ikase and Edgars Cirša

Abstract

All growers prefer to obtain a first harvest as soon as possible. The aim of this study was to identify an effective tree training system for new Latvian plum cultivars, which provides the highest yield and fruit quality. The trial was established in 2012 at the Institute of Horticulture (formerly Latvia State Institute of Fruit-Growing) and included cultivars ‘Ance’, ‘Adelyn’, and ‘Sonora’; and the controls ‘Victoria’ and ‘Jubileum’. Planting distances were 4 × 2.5 m, and the rootstock was Prunus cerasifera. Tree training was done using four systems: two systems with branch bending (Heka espalier and spindle); and two systems without bending (standard (round) and flat crown). Evaluation of average fruit weight and yield per trunk cross section area (TCSA) was done from 2015 to 2017. The Heka espalier and spindle systems had first yield in 2015, but systems without bending had first yield only in 2016. Average yield per TCSA was significantly higher for the Heka espalier system (0.49 kg·cm−2) than for the spindle system (0.24 kg·cm−2), standard crown system (0.17 kg·cm−2), and flat crown system (0.30 kg·cm−2). Cultivar ‘Victoria’ had the highest yield among all systems. Average fruit size showed the same results: the biggest fruits were obtained with the Heka espalier system, and the smallest for systems without bending in the standard crown.

Open access

Simone A. Ludwig

Abstract

An intrusion detection system (IDS) is an important feature to employ in order to protect a system against network attacks. An IDS monitors the activity within a network of connected computers as to analyze the activity of intrusive patterns. In the event of an ‘attack’, the system has to respond appropriately. Different machine learning techniques have been applied in the past. These techniques fall either into the clustering or the classification category. In this paper, the classification method is used whereby a neural network ensemble method is employed to classify the different types of attacks. The neural network ensemble method consists of an autoencoder, a deep belief neural network, a deep neural network, and an extreme learning machine. The data used for the investigation is the NSL-KDD data set. In particular, the detection rate and false alarm rate among other measures (confusion matrix, classification accuracy, and AUC) of the implemented neural network ensemble are evaluated.