Study of plum cultivars in Norway

This report presents results of two plum cultivars and selections trials, performed during 2013-2021 and 2016-2021 at Ullensvang. In total, 19 plum cultivars were evaluated: 4 from the Institute of Horticulture, Čačak, Serbia; 9 cultivars and selections bred by Einar Ruud, Søgne; 3 plum selections from Graminor, Njøs and 1 cultivar from NMBU. Cultivars Opal and Čačanska lepotica served as control. The aim of these reported plum cultivar trials was to investigate recently released plum cultivars and premium selections from Norwegian and Serbian breeding programs from pomological, agronomical, and biochemical point of view, identify the most important quality parameters, and select cultivars with desirable traits for the modern market in Norway. Based on overall fruit quality and tree productivity, selections NPr. 458 and Anne (R21) (Rudiplomme, if a DNA-test reveal that it is the same as the cultivar Anne (R 21)) are selected for fresh consumption and can be recommended for further commercial growing tests. Due to very sweet and good fruit taste, cultivars Boranka and Ellen might be used for jam.Study of plum cultivars in NorwaypublishedVersio

Introduction of new fruit crops to Norway

Global warming benefits enrichment of the assortment of cultivated fruit trees. New fruit species, less winter hardy, demanding higher temperatures during their growth and longer vegetation period, could become new commercial crops in Norwegian orchards. Up to now there is a lack of knowledge and experience with new fruit species in Norway. Main goal of the project was to justify the possibilities of introduction of new fruit crops namely table/wine grapes, peaches, apricots, and nectarines. The project implementation was based on literature analysis, questionnaires of growers and scientists, information gathered during the visits to scientific institutions and farmers in Norway, Sweden, Latvia, and Lithuania. According to growers’ experience and research performed in Norway, neighbouring countries and in regions with similar climate, a number of wine grape and apricot cultivars can be successfully grown in Norway. However, table grapes, peach and especially nectarine are more risky crops. After comprehensive analysis of cultivar characteristics and management, recommendations for the introduction of new cultivars were prepared for commercial growing or additional cultivar evaluation trials.Introduction of new fruit crops to NorwaypublishedVersio

Performance of Sweet Cherry Cultivars and Advanced Selections on Gisela 5 Rootstock in Young Orchards

Six sweet cherry cultivars and two advanced selections of Gisela 5 rootstock were tested in 2015–2021 at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Fruit trees were planted at distances of 4.5 × 2.5 m and trained as spindles. Orchard floor management included frequently mown grass in alleyways with herbicide strips along tree rows. Cultivars ‘Mindaugė’ and ‘Irema BS’ were the most vigorous at the end of the seventh leaf. Their trunk diameter achieved 11.6 cm. The ‘Merchant’ cultivar had the smallest trunk diameter—9.3 cm. The average yield in 2018–2021 ranged from 2.75 t/ha for ‘Vega’ to 8.73 t/ha for ‘Regina’. Cultivars ‘Regina’, ‘Sunburst’, ‘Irema BS’ and ‘Merchant’ had the highest cumulative yield efficiency of 0.440–0.503 kg/cm2 with respect to the trunk cross-section area (TCSA). The least productive cultivar ‘Vega’ produced fruits of the highest average weight—9.9 g. Fruits of ‘Regina’ and ‘Sunburst’ were large as well—8.8–9.1 g. ‘Irema BS’ fruits had the highest soluble solids content (SSC)—20.2%. The lowest SSC was recorded in ‘Merchant’ and ‘Sunburst’ fruits—14.7–15.8%. The yield of advanced selection, No. 102, equaled to the yield of cv. ‘Regina’. No. 102 had a high fruit weight, and fruits were distinguished by attractiveness and taste.publishedVersio

Effects of Rhizobacteria Application on Leaf and Fruit Nutrient Content of Different Apple Scion–Rootstock Combinations

The plant pomological characteristics and physiological behaviors of genotypes in modern apple cultivation could be different depending on the use of rootstock, changing growth ecology and application of biological control agents. The aim of this research was to determine the effects of rhizobacteria application on leaf and fruit nutrient contents in different apple scion–rootstock combinations. This study was carried out with seven standard cultivars (Scarlet Spur, Red Chief, Fuji, Jeromine, Galaxy Gala, Granny Smith, and Golden Reinders) budded on M.9 and MM.106 rootstocks. In the experiment, trees were sprayed by a nitrogen + phosphorus solvent rhizobacteria three times, with an interval of 15 days in the spring period. The effect of rhizobacteria application on leaf and fruit nutrient contents was statistically significant and provided generally significant positive contributions, except for leaf Mg content. Comparing both rootstocks, the positive effect of bacterial application was higher on the M.9 rootstock for leaf N and B content and fruit N and Fe content, and on the MM.106 rootstock for other nutrient content. While the effects of bacterial application on the basis of cultivars were generally positive, the highest positive contribution was made in leaf P content (10.7%) and fruit Mn content (32.1%) of the Fuji cultivar. Considering the total increase in nutrients in scion–rootstocks combination, rhizobacteria application had a positive effect on the leaf nutrient contents in Golden Reinders/MM.106, but not leaf K content. The highest increases in leaves of scion-rootstock combinations were determined as 4.0% in N content in Granny Smith/M.9, 14.1% in P content in Scarlet Spur/MM.106, 7.1% in K content in Fuji/MM.106, 4.4% in Ca content in Jeromine/M.9, and 14.0% in Mg content in Granny Smith/MM.106. The highest increase in fruit nutrient contents was between 4.9% (N content) and 13.5% (Ca content) for macro elements, and between 9.5% (Cu content) and 41.8% (Mn content) for microelements. The results of the present study may provide significant leads for further studies on this subject.Effects of Rhizobacteria Application on Leaf and Fruit Nutrient Content of Different Apple Scion–Rootstock CombinationspublishedVersio

Management of Japanese quince (Chaenomeles japonica) orchards

In this paper, advice for establishment and management of Japanese quince (Chaenomeles japonica) orchards is summarised. Japanese quince is a minor fruit crop in Latvia and Lithuania, currently being developed by plant breeding research. Preferences for site and soil are discussed and recommendations for planting and field management are proposed

Relationships Among the Rootstock, Crop Load, and Sugar Hormone Signaling of Apple Tree, and Their Effects on Biennial Bearing

Adjustable crop load primarily involves bud manipulation, and usually switches from vegetative to reproductive buds. While this switch is not fully understood, it is still controlled by the ratio of hormones, which promote or inhibit bud formation. To determine the reasons for biennial bearing, the effect of apple rootstock, scion cultivar, crop load, as well as metabolic changes of endogenous phytohormones [zeatin, jasmonic acid, indole-3 acetic acid (IAA), abscisic acid (ABA), and gibberellins 1, 3, and 7 (GAs)], and soluble sugars (glucose, fructose, and sorbitol) were evaluated, and their connections with return bloom and yield of apple tree buds were analyzed. Cultivars “Ligol” and “Auksis” were tested on five rootstocks contrasting in induced vigor: semi-dwarfing M.26; dwarfing M.9, B.396, and P 67; and super-dwarfing P 22. Crop load levels were adjusted before flowering, leaving 75, 113, and 150 fruits per tree. Principal component analysis (PCA) scatter plot of the metabolic response of phytohormones and sugars indicated that the effect of the semi-dwarfing M.26 rootstock was significantly different from that of the dwarfing M.9 and P 67, as well as the super-dwarfing P 22 rootstocks in both varieties. The most intensive crop load (150 fruits per tree) produced a significantly different response compared to less intensive crop loads (113 and 75) in both varieties. In contrast to soluble sugar accumulation, increased crop load resulted in an increased accumulation of phytohormones, except for ABA. Dwarfing rootstocks M.9, B.396, and P 67, as well as super-dwarf P 22 produced an altered accumulation of promoter phytohormones, while the more vigorous semi-dwarfing M.26 rootstock induced a higher content of glucose and inhibitory phytohormones, by increasing content of IAA, ABA, and GAs. The most significant decrease in return bloom resulted from the highest crop load in “Auksis” grafted on M.9 and P 22 rootstocks. Average difference in flower number between crop loads of 75 and 150 fruits per tree in “Ligol” was 68%, while this difference reached ~ 90% for P 22, and ~ 75% for M.9 and M.26 rootstocks. Return bloom was dependent on the previous year’s crop load, cultivar, and rootstock.publishedVersio

Testing new apple cultivars for Norwegian growing conditions

NIBIO Ullensvang har i perioden 2012-2019 gjennomført rettleiingsprøving av samla 11 eplesortar og -seleksjonar. Føremålet var å skaffa norske fruktdyrkarar sortar som gjev stor avling med kvalitetsfrukt og er tilpassa det norske klimaet. Sortane vart poda på den svaktveksande grunnstamma M9. Pomologiske karakterar og fruktkvalitet vart vurderte og detaljert informasjon om dei ulike sortane er gjeve i denne rapporten. Sortane Asfari og Elstar Boerekamp Excellent- Star® vert tilrådde til kommersiell fruktdyrking. Sorten Tiara kan dyrkast til jus og som dekorasjonsfrukt sidan den har raudt fruktkjøt. Sorten Pinova bør prøvast vidare. På grunn av svak fruktkvalitet og sein modning er fylgjande sortar og utval ikkje tilrådde for dyrking under norske tilhøve: 1/05, 58/06, A 75, Galmac, Jugala, Crimson Crisp og Elshof.publishedVersio

Propagation of Japanese quince (Chaenomeles japonica) plants

In this paper, research on vegetative propagation of Japanese quince (Chaenomeles japonica) plants is reported and summarised. An efficient system for propagation of Japanese quince based on softwood cuttings was developed. For this purpose, 20 cm long top cuttings, with the base of the cuttings soaked in 30 mg/l IBA for 18 hours, were used. Although hardwood cuttings seemed less useful for propagation of chaenomeles plants, a high rooting percentage was obtained using 20 cm long base cuttings, soaked in 100 mg/l IBA for 24 hours. Procedures for micropropagation were improved and micropropagation was shown to be a very efficient method for propagation of Japanese quince, with an average proliferation rate of around 3–4 and a rooting percentage of over 90%. For the proliferation phase a medium consisting of complete MS medium with macronutrients reduced to 3/4, iron added as NaFeEDTA, 1.0 g/l BA as growth regulator and 35 g/l sucrose as a source of carbohydrates, was useful in large scale commercial propagation. For rooting of microshoots, a shoot elongation phase of two weeks and a soaking of microshoots in 250 mg/l IBA before planting seemed important. It was shown that the ability to form roots was genotype dependent. Rooting potential should therefore be evaluated during plant breeding and selection

Breeding strategies for the fruit crop Japanese quince (Chaenomeles japonica)

In this paper, an ideotype for the fruit crop Japanese quince (Chaenomeles japonica) is established and traits to be specifically considered for selection and breeding are discussed: adaptation and hardiness, disease resistance, thorns, suckering, growth, rooting, time of ripening, yield, amenability for mechanical harvesting and fruit quality. In addition, test guidelines and descriptors for Chaenomeles species are presented. Short-term and long-term breeding strategies are suggested, based on a study of general and specific combining ability for plant vegetative traits, fruit yield and morphology traits, and fruit biochemistry traits. An efficient breeding strategy for Japanese quince could be based on recurrent selection. However, extensive test crosses and progeny tests in well-designed field trials should also be considered since some important traits are controlled by additive as well as non-additive genes