Blueberry Cuttings Research Articles

Influence of indole-butyric acid and substrate type on vegetative propagation of native Peruvian blueberry (Vaccinium sp.)

In the Amazon region of Peru, native blueberries are found in high Andean areas, where they are associated with small shrubs and mosses. These blueberries prefer shallow soils with a sandy-clay texture and low fertility. However, their population is threatened by their limited regenerative capacity and various anthropogenic factors. The aim of this study was to evaluate the influence of indole butyric acid and substrate type on the vegetative propagation of native Peruvian blueberry (Vaccinium sp.) grown in microtunnel. The experiment was conducted under a complete randomized design with the factorial arrangement; A: substrate (sand 100%, sand + coconut fiber 1:1 v/v and coconut fiber 100%) and B: AIB concentrations (1, 2 and 3 g L-1) and control (0 g L-1), giving 12 treatments, three replicates and 36 experimental plots. In the field, apical shoots of blueberry with semi-lignified and vigorous stems were collected. In the laboratory, they were disinfected with fungicide and cut to a size of 7 cm. Subsequently, they were treated with AIB and planted in prepared substrates. After 120 days in the microtunnel, it was observed that blueberry cuttings showed higher survival in sand + coconut fiber (94.7%), rooting (73.8%), root number (6.9), and root growth (9.2). AIB concentrations at 2 and 3 g L-1 had a greater effect on rooting, with values above 60%. The use of suitable substrates and auxin concentrations significantly favors the vegetative propagation of native blueberries. This propagation technique is postulated as a promising alternative for the mass propagation of this species for the conservation and rehabilitation of degraded ecosystems.

Effects of cadmium stress on the growth, physiology, mineral uptake, cadmium accumulation and fruit quality of 'Sharpblue' blueberry

Cadmium (Cd) contamination is becoming a widespread environmental problem, and Cd toxicity risk is increasing in blueberries, typical acidophilous plants. However, studies on the physiological mechanisms of Cd toxicity affecting the growth of blueberry plants and fruits remain limited. Herein, a pot experiment involving four treatments, CK (0 mg·kg−1), Cd1 (2.5 mg·kg−1), Cd2 (15 mg·kg−1) and Cd3 (50 mg·kg−1), was conducted to investigate the effects of Cd stress on the growth, fruit quality, physiological characteristics, mineral composition and Cd uptake of 'Sharpblue' blueberry cuttings, and relationships between physicochemical indices and phenotypic data under Cd stress were analyzed via principal component analysis and Mantel's test. Compared with CK, Cd treatment led to chlorosis (decrease in SPAD and N content) in 'Sharpblue' leaves and inhibited increases in plant height, basal stem, crown width and biomass (dry weight), with the most significant changes in the 50 mg·kg−1 Cd treatment. The size and thickness of the upper epidermal cells, as well as the thickness of the palisade mesophyll and spongy tissues of 'Sharpblue' were significantly reduced at Cd > 15 mg·kg−1, while the density of stomata was significantly increased. Moreover, Cd stress reduced the yield (decrease in size and single-fruit weight) and quality (decrease in anthocyanin, flavonoid and total phenol content and increase in titratable acid content) of 'Sharpblue' fruits, and Cd content in fruit exceeded the Chinese food safety threshold of 0.05 mg·kg−1 when Cd > 15 mg·kg−1. The Cd enrichment capacity of different organs of 'Sharpblue' plants was in the following order: root > shoot > leaf > fruit, and the 50 mg·kg−1 Cd treatment significantly inhibited the uptake of Fe, Mn, Cu, and Zn. Additionally, 'Sharpblue' plants responded to H2O2 and malondialdehyde accumulation in different organs under Cd stress by regulating levels of osmoregulatory substances (soluble protein (SP), soluble sugar, and proline) and altering the activities of catalase, superoxide dismutase, ascorbic acid, and glutathione in the antioxidant system. Finally, correlation analysis revealed that Mg, Fe, Mn, Cu, Cd, H2O2, SP, SPAD, N, anthocyanin, titratable acid, flavonoids, and total phenols were strongly correlated with 'Sharpblue' growth, leaf and fruit phenotype under Cd stress. These findings provide theoretical information for soil safety management and the breeding of Cd-tolerant cultivars during blueberry cultivation, as well as for the study of Cd stress response mechanisms in acidophilous plants.

Effects of plant growth-promoting rhizobacteria on blueberry growth and rhizosphere soil microenvironment.

Plant growth-promoting rhizobacteria (PGPR) have a specific symbiotic relationship with plants and rhizosphere soil. The purpose of this study was to evaluate the effects of PGPR on blueberry plant growth, rhizospheric soil nutrients and the microbial community. In this study, nine PGPR strains, belonging to the genera Pseudomonas and Buttiauxella, were selected and added into the soil in which the blueberry cuttings were planted. All the physiological indexes of the cuttings and all rhizospheric soil element contents were determined on day 6 after the quartic root irrigation experiments were completed. The microbial diversity in the soil was determined using high-throughput amplicon sequencing technology. The correlations between phosphorus solubilization, the auxin production of PGPR strains, and the physiological indexes of blueberry plants, and the correlation between rhizospheric microbial diversity and soil element contents were determined using the Pearson's correlation, Kendall's tau correlation and Spearman's rank correlation analysis methods. The branch number, leaf number, chlorophyllcontentand plant height of the treated blueberry group were significantly higher than those of the control group. The rhizospheric soil element contents also increased after PGPR root irrigation. The rhizospheric microbial community structure changed significantly under the PGPR of root irrigation. The dominant phyla, except Actinomycetota, in the soil samples had the greatest correlation with phosphorus solubilization and the auxin production of PGPR strains. The branch number, leaf number, and chlorophyllcontent had a positive correlation with the phosphorus solubilization and auxin production of PGPR strains and soil element contents. In conclusion, plant growth could be promoted by the root irrigation of PGPR to improve rhizospheric soil nutrients and the microenvironment, with modification of the rhizospheric soil microbial community. Plant growth could be promoted by the root irrigation of PGPR to improve rhizospheric soil nutrients and the microenvironment, with the modification of the rhizospheric soil microbial community. These data may help us to better understand the positive effects of PGPR on blueberry growth and the rhizosphere soil microenvironment, as well as provide a research basis for the subsequent development of a rhizosphere-promoting microbial fertilizer.

Crescimento e atributos fisiológicos de mudas de mirtileiro inoculadas com fungos micorrízicosarbusculares

ABSTRACT: High-quality seedlings are one of the key factors in achieving high yield and precocity of blueberries. The inoculation of arbuscular mycorrhizal fungi (AMF) can enhance the development of seedlings in the nursery, ensuring more vigorous seedlings in a shorter time. This study evaluated the effect of inoculation of arbuscular mycorrhizal fungi on the development of ‘PowderBlue’blueberryseedlings. The treatments were arranged in a 4 x 2 factorial scheme, in which the first factor was the arbuscular mycorrhizal fungi Gigaspora rosea, Glomus clarum, G. rosea + G. clarum, and a control level without mycorrhizae, while the second factor consisted of usingindole-3-butyric acid(IBA) and a control level without IBA. Semi-hardwood cuttings were planted in pots containing sterilized soil and kept in a greenhouse for 660 days. The percentage of rooted cuttings, plant height, root system length, shoot dry mass, root dry mass, total dry mass, peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, SPAD index, mycorrhizal efficiency and dependence, number of spores, and soil basal respiration were evaluated. Plants inoculated with G. clarum without IBA and inoculated with G. rosea with IBA showed higher dry matter and SOD and POD enzyme activities, but the use of IBA had a negative effect on the fungus. The inoculation of blueberry cuttings with G. clarummay help seedlingdevelopment, thus improving biometric and biochemical parameters. Furthermore, the plant regulator IBAwas essential in establishing the symbiosis between blueberry and the AMF G. rosea.

Influence of various types of light on growth and physicochemical composition of blueberry (Vaccinium corymbosum L.) leaves

It is important to use light that has a positive effect on plants. For plant growers, achieving the lowest possible cost of shrub production is crucial. We investigated the influence of light (white and violet LEDs as well as fluorescent white and red light) on the rooting and growth of blueberry cuttings (V. corymbosum L.) 'Aurora' and 'Huron'. Blueberry cuttings (4 cm tall) were planted into boxes with peat, which were placed in a phytotron at 22 °C and illuminated for 16 hours a day. The plants died under the red fluorescent light source and, therefore, we discontinued its use. The other three light sources had a positive effect on plant growth and development. The light source had little effect on the content of macroelements in the leaves. Plants grown under white fluorescent and white LED light did not significantly differ in the height (22.0-25.8 cm), proline (4.67-7.23 μmol g-1), and polyphenol content (4987-5212 mg 100 g-1). In both cultivars, the violet LED light reduced plant growth and increased the content of polyphenols (6,448 mg 100 g-1) and proline (8.11-9.06 μmol g-1) in the leaves, which may indicate abiotic stress. 
 During the rooting of highbush blueberry cuttings, it is advisable to use white LED light. It has a positive economic impact on crop production due to low electricity consumption and it benefits the environment by eliminating mercury. The plant quality is similar to that of fluorescent white light.

Survey of Potential Root Pathogens in Softwood Cuttings Collected from Georgia Blueberry Nurseries

Survey sampling of 16 blueberry nurseries propagating softwood cuttings was conducted in 2007 and 2008 to determine which soilborne plant pathogens were most prevalent in commercial blueberry propagation systems in southern Georgia. Samples were collected four times: June (early), September (mid), and October (late) in the 2007 growing season, with additional sampling of overwintered cuttings in April 2008. This survey revealed that Calonectria ilicicola (Cylindrocladium parasiticum), causing Cylindrocladium root rot, is a primary pathogen of blueberry cuttings in southern Georgia. The organism was isolated consistently during all four survey dates with a cutting-level incidence of 3.6, 10.2, 36.4, and 14.3% in the first through fourth samplings, respectively. Rhizoctonia spp. were recovered less frequently and were only present during the first (10.9% cutting-level incidence), third (4.6%), and fourth survey dates (3.6%), whereas the oomycetes Pythium and Phytophthora were detected only on the second survey date. Fusarium spp. were isolated commonly (29.1% incidence in the first, 12.2% in the second, 18.2% in the third, and 7.1% in the fourth sampling), but pathogenicity remains uncertain. Across all survey dates, Calonectria, Rhizoctonia, oomycetes, and Fusarium were recovered at least once from 43.8, 18.8, 12.5, and 87.5% of nurseries surveyed, respectively. When nursery-level data on pathogen presence or absence collected from this survey were analyzed in relation to a survey of production practices used by these same propagators, the practice of reusing growth media was found to be significantly associated with Calonectria presence.

Rooting of Wild Blueberry (Vaccinium spp.) Cuttings From the Peruvian Northeast

AbstractThe objective of this study was to evaluate the effect of indole-3-butyric acid (IBA) on the rooting of five wild accessions of blueberry (HCHA-262, HCHA-271, HCHA-283, HCHA-286, and HCHA-290) obtained from natural populations in the province of Chachapoyas (northern Peru). Buds were collected from the middle third of the plant and treated with IBA at concentrations of 0, 1,000, 2,000, and 3,000 mg L−1. The results indicated that of the IBA doses, the 2,000-mg L−1dose achieved the best effects on the rooting percentage and the lengths and numbers of roots and shoots of each accession studied. Accessions HCHA-262 and HCHA-283 showed greater regeneration of new seedlings than the other accessions after 45 days. The rhizogenic capacity of the cuttings varied because of the influences of both the IBA concentration and the genotype of the mother plant.

Development of methods for preparing lignified cuttings of tall blueberry for rooting

When propagating tall blueberries by lignified cuttings, the optimal type of substrate and the method of preparing cuttings for rooting have been established. It has been experimentally proven that lignified cuttings before planting for rooting are effectively furrowed (wounding in the lower part of the cuttings along the shoot axis), treated with Ukorzeniacz Baqua growth powder (0.2%) and rooted in a substrate consisting of high peat. At the same time, the rooting rate of the Bluecrop variety was 69% versus 47% in the control rooted on high-moor peat and against 37% in the control rooted on a mixture of high-moor peat with perlite. And in the Northland variety-79% versus 59% in the control rooted on high-moor peat and against 52% in the control rooted on a mixture of high-moor peat with perlite (1:1).

Methods of application of indolebutyric acid and basal lesion on ‘Woodard’ blueberry cuttings in different seasons

Abstract Blueberry cuttings are difficult to root, so alternatives that maximize their rhizogenic potential are essential for the expansion of the crop. The objective of this work was to evaluate the effect of the basal lesion and different methods of indolebutyric acid (IBA) on the rooting of ‘Woodard’ herbaceous cuttings, collected in two seasons. The experimental design used was completely randomized in a 3x2x2 factorial arrangement, totaling 12 treatments and five replications. The factors consisted of different ways of IBA application (talc and alcohol in the concentration of 1,000 mg L-1, and without IBA), season of collection (autumn and summer), and two types of cuttings (with and without lesion in the basal portion). Two hundred days after the beginning of the experiment, there was no significant effect of the basal lesion on the rooting of the cuttings. However, it was found that rooting is influenced by the season of collection, with greater leaf retention, dry weight, number of roots per cutting, length of roots and length of the largest root collected in summer. The application of IBA talc provided a higher percentage of rooted cuttings (61.0%) in relation to alcohol (31.0%) and control (41.0%) when collected in the autumn. There was no difference between seasons when IBA was applied with talc, however, the application with alcohol solution and the control resulted in higher percentages of rooted cuttings in the summer (70.0% and 67.0%, respectively). Summer was considered the best season to collect ‘Woodard’ blueberry cuttings, although the IBA applied with talc has increased the percentage of rooted cuttings in the autumn. The basal lesion did not promote an increase in rooting.

Evaluation of Rooting Media Containing Fallen Needles of Japanese Black Pine for Blueberry Cuttings

Evaluation of Rooting Media Containing Fallen Needles of Japanese Black Pine for Blueberry Cuttings

Symbiotic fungi in nature Finnish peat moss promote vegetative growth in rabbiteye blueberry cuttings

In nature conditions, mutualization of ericaceous plant (Ericaceae) roots with mycorrhizal fungi or other soil symbiotic fungi improves efficiency on nutrient uptake and tolerance to heavy metal stress. Effects of ericoid mycorrhizal fungi (EMF) or dark septate endophyte (DSE) colonization have been evaluated in highbush blueberry (Vaccinium corymbosum) but remained unclear in rabbiteye blueberry (V. virgatum Ait.). In this study, callused cuttings of ‘NTU-104’ rabbiteye blueberry were grown in substrate containing either sterilized (SP) or unsterilized (UP) nature Finnish peat moss as a fungal inoculum. Vegetative growth, fungal colonization frequency (Cf) and intensity (Ci), substrate pH and electrical conductivity (EC), and plant nutritional elements were assessed. Sterilization did not completely exclude fungi resources in the peat moss and colonization of EMF and DSE was found in both SP and UP substrate types. Regardless, UP treatment resulted in greater total Cf (69.3%) and Ci (9.91%) than those of SP (41.49% and 6.17%, respectively). In either substrate type, both Cf and Ci of DSE were greater than those of EMF. Plants in UP treatment produced more shoots (2.33), number of leaves (76.33), greater total leaf area (494.18 cm2), and shoot length (121.78 cm) than in SP substrate (1.67, 24.17, 116.13 cm2, and 30.22 cm, respectively). Fresh weights of roots, shoots, and leaves in UP plants were significantly greater (7.57, 9.64, and 15.25 g, respectively) than in SP plants (1.29, 2.62, and 3.08 g, respectively). Dry weights of roots, shoots, and leaves in UP plants were also significantly greater (4.34, 2.37, and 4.51 g, respectively) than in SP plants (0.67, 0.47, and 0.90 g, respectively). Concentrations of phosphorous and magnesium in roots and potassium in shoots were increased in UP plants while other nutritional elements remained consistent. Contents of all nutritional elements were increased in UP plants due to greater dry weight. After the establishment of the transplants, pH and EC of both substrate types were in the optimal range for blueberries but significant lower pH while higher EC were measured in UP substrate. The results indicated that using nature Finnish peat moss as a symbiotic fungi inoculum was capable of establishing symbiotic fungal colonization and promoting rooting and vegetative growth in rabbiteye blueberry cuttings.

Effect of Bottom Heating and Medium on Rooting of Hardwood Cuttings of Blueberry

Maviyemiş ılıman iklim kuşağındaki kuvvetli asit topraklarda yetişebilen çalı formunda bitkisi olan bir üzümsü meyvedir. Bu çalışmada Berkeley maviyemiş çeşidine ait bitkilerden Şubat ayında alınan sert odun çelikleri Nisan ayına kadar kayın+çam talaşı içinde +1°C sıcaklık ve %80-85 nispi nem şartlarında muhafaza edilmişlerdir. Nisan ayında 15 cm boyunda hazırlanarak 2000 ppm indol-3-butrik asit (IBA) uygulandıktan sonra ısıtmasız cam seradaki alttan ısıtmalı tavalarda ve torf ile torf+perlit ortamına dikilen çeliklere 4 farklı alttan ısıtma sıcaklığı (yok-kontrol, 20, 23 ve 26°C) uygulanmıştır. Mistleme sulama ve %55 gölgeleme altında tesadüf blokları deneme deseninde 3 tekerrürlü olarak kurulan denemede her tekerrürde 20 adet odun çeliği kullanılmıştır. Köklü çelikler 8 hafta sonra ortamlardan sökülerek köklenme oranı (%), köklenme derecesi (1-9 skalası) saptandıktan sonra saksılara dikilen köklü çeliklerden elde edilen fidanlarda fidan randımanı (%) Ekim ayında saptanmıştır. Torf+perlit x 26°C kombinasyonu köklenme oranı (%75.00), fidan randımanı (%73.00) ve köklenme derecesi (5.35) bakımından en yüksek değerleri vermiştir. Berkeley maviyemiş çeşidinin sert odun çelik ile çoğaltılmasında 26°C alttan ısıtma sıcaklığı ve torf+perlit ortamının kullanılması önerilir.

Transcriptomic profiling and discovery of key genes involved in adventitious root formation from green cuttings of highbush blueberry (Vaccinium corymbosum L.)

BackgroundPropagation of cuttings is frequently used in various plant species, including blueberry, which shows special root characteristics that may hinder adventitious root (AR) formation. AR formation is influenced by various factors, and auxin is considered to play a central role; however, little is known of the related regulatory mechanisms. In this study, a comparative transcriptome analysis of green cuttings treated with or without indole-butyric acid (IBA) was performed via RNA_seq to identify candidate genes associated with IBA-induced AR formation.ResultsRooting phenotypes, especially the rooting rate, were significantly promoted by exogenous auxin in the IBA application. Blueberry AR formation was an auxin-induced process, during which adventitious root primordium initiation (rpi) began at 14 days after cutting (DAC), root primordium (rp) was developed at 21 DAC, mature AR was observed at 28 DAC and finally outgrowth from the stem occurred at 35 DAC. Higher IAA levels and lower ABA and zeatin contents might facilitate AR formation and development. A time series transcriptome analysis identified 14,970 differentially expressed genes (DEGs) during AR formation, of which there were 7467 upregulated and 7503 downregulated genes. Of these, approximately 35 candidate DEGs involved in the auxin-induced pathway and AR formation were further identified, including 10 auxin respective genes (ARFs and SAURs), 13 transcription factors (LOB domain-containing protein (LBDs)), 6 auxin transporters (AUX22, LAX3/5 and PIN-like 6 (PIL6s)) and 6 rooting-associated genes (root meristem growth factor 9 (RGF9), lateral root primordium 1 (LRP1s), and dormancy-associated protein homologue 3 (DRMH3)). All these identified DEGs were highly upregulated in certain stages during AR formation, indicating their potential roles in blueberry AR formation.ConclusionsThe transcriptome profiling results indicated candidate genes or major regulatory factors that influence adventitious root formation in blueberry and provided a comprehensive understanding of the rooting mechanism underlying the auxin-induced AR formation from blueberry green cuttings.

Determining the Rooting Ability of Hardwood Cuttings of Blueberry (Vaccinium corymbosum L.) cv. ‘Bluecrop’ Stored in Refrigerating Conditions

This experiment has been carried out in order to determine the rooting ability of hardwood cuttings of the blueberry cultivar ‘Bluecrop’ collected during the deep dormant winter period in the last part of January. In order to induce the adventitious roots formation, the cuttings were stimulated using Indol Butyric Acid (IBA) and Naphthalene Acetic Acid (NAA) in various concentrations (1500, 3000, 4500 ppm), whilst one row in each box remained intact (control). The collection of cuttings off the mother plant at the beginning of January enable the nutrients and other matter that help the process of rooting not to move from the base of cutting towards the top and consequently they remain at the base of cutting which results with quite a high rooting percentage (up to 72.5%) compared to the cuttings collected in February with rooting percentage of 67.5% and in March (52%). In both types of substrate, turf and turf-perlite 2:1 and in different time periods when cuttings have been collected, IBA proved to be better in inducing adventitious roots compared to NAA.

Association of Indolebutyric Acid with Azospirillum brasilense in the Rooting of Herbaceous Blueberry Cuttings

Association between auxins and plant growth-promoting bacteria can stimulate root growth and development of fruit crop nursery plants, and can be a promising biological alternative to increase the rooting of cuttings. The objective of this study was to assess the viability of producing ‘Powderblue’ blueberry nursery plants from cuttings using different doses of indolebutyric acid (IBA) in association with Azospirillum brasilense. The following treatments were tested: 0 (control); 500 mg L−1 of IBA; 1000 mg L−1 of IBA; A. brasilense; 500 mg L−1 of IBA + A. brasilense; and 1000 mg L−1 of IBA + A. brasilense. The experimental design was completely randomized, with six treatments and four replicates, and each plot (box) consisted of 10 cuttings. The boxes were arranged in a mist chamber with an intermittent regimen controlled by a timer and solenoid valve. After 90 days, the following variables were assessed: rooted cuttings; survival of cuttings; foliar retention; sprouting; cuttings with callus; root dry mass per cutting; number of roots per cutting; and root length. It was observed that the application of IBA with the A. brasilense rhizobacteria increased the number of roots of ‘Powderblue’ blueberry cuttings, while the treatments with IBA alone and IBA 1000 mg L−1 + A. brasilense increased the root length of cuttings. However, treatments with IBA and A. brasilense had no impact on % rooted cuttings and % survival of cuttings.

Indole butyric acid application methods in ‘Brite Blue’ blueberry cuttings collected in different seasons

The cultivation of temperate fruits such as blueberries is expanding in Brazil. However, lower technical information on plant cultivation and difficulties in propagation are among the limiting factors in the expansion of the blueberry cultivation. The objective of this study was to evaluate the influence of different methods of indole butyric acid (IBA) application on the rooting of ‘Brite Blue’ blueberry herbaceous cuttings, with and without lesions, collected in two different seasons. The experimental design was completely randomized, with five replicates, each consisting of 10 cuttings, in a 3x2x2 factorial arrangement. Two IBA application methods (talc and alcohol) and control (no application), with two collection seasons (autumn and summer), and cuttings with and without basal injury, consisted of two superficial cuts on the basal part, on opposite sides, were evaluated. The cuttings were put in carbonized rice husk substrate, inside perforated plastic boxes (44x30x7 cm), and maintained in a mist chamber with intermittent regime. After 200 days, it was verified that the ‘Brite Blue’ blueberry was influenced by the cutting collection season, with higher rooting percentage when basal lesion was performed in cuttings collected in the summer. The IBA application of 1000 mg L-1 does not influence the rooting and root development of the cuttings.

Regeneration ability of different cultivars of the highbush blueberry (<i>Vaccinium corymbosum</i> L.) propagated by green stem cuttings

An assessment of the regenerative capacity was made for 20 highbush blueberry cultivars and 3 half-highbush blueberry cultivars introduced in Belarus, based on 9-year research results. Has been established that the regeneration ability of the green cuttings of blueberry is genetically determined with varying degrees of severity in one or another cultivar. The results obtained allowed to classify blueberry cultivars according to their root-forming ability into three groups: easily rooted ((‘Elizabeth’, ‘Hardyblue’, ‘Northland’), medium rooted ((‘Blueray’, ‘Coville’, ‘Croatan’, ‘Darrow’, ‘Denise Blue’, ‘Herbert’, ‘Jersey’, ‘Northcountry’, ‘Reka’, ‘Rubel’) and difficult to resist (‘Bluecrop’, ‘Bluetta’, ‘Bluerose’, ‘Carolinablue’, ‘Duke’, ‘Earliblue’, ‘Nelson’, ‘Northblue’, ‘Patriot’, ‘Weymouth’). It is reliably shown that one hundred varieties of this crop, possessing a higher rootforming ability, produce plants with large biometric parameters of the above-ground sphere. The blue cuttings of highbush and half-highbush blueberries have a satisfactory regenerative capacity, which makes it possible to use this method of vegetative propagation for replication and to obtain planting material of this culture in Belarus.

ОПТИМИЗАЦИЯ ТЕХНОЛОГИИ ЗЕЛЕНОГО ЧЕРЕНКОВАНИЯ ГОЛУБИКИ ВЫСОКОРОСЛОЙ

The objective of this work was to determine the effectiveness of auxin growth regulators for processing of green cuttings of highbush blueberry before planting them for rooting. Experiments were conducted in 2016-2017, in the Research and Production Nursery peasant-farmers hold “Cherry garden”, village Besovo, Kaluga region. The experiments were performed on highbush blueberry Bluecrop and Northland varieties. Before the rooting of green cuttings treatments with synthetic auxin growth regulators in the form of water, alcohol solutions and growth powder were performed. Alcohol solution of indole-3-butyric acid (IBA) (5 g/l) or growth powder Ukorzeniacz (0.2 %) were shown to be the most effective stimulators of rooting in green cuttings “with heel”. Not treated with any growth regulators plants were used as a control. Rooting rates of green cuttings of Bluecrop blueberry variety were 73-78 % in comparison to 49 % of the control, whereas Northland blueberry variety showed 74- 77 % rooting rates in comparison to 60 % in the control.

Multiplication of blueberry mini-cuttings in different growth media

The objective of this study was to evaluate the influence of length of herbaceous cuttings and substrates on the multiplication of ‘Woodard’ and ‘Briteblue’ blueberry cuttings. The experimental design was entirely randomized. Four replicates of 10 cuttings per plot in a 3x2 factorial arrangement, three cutting lengths (5, 8, and 12 cm) and two types of substrate (rice hull ash and coconut fiber) were evaluated. The cuttings were collected in two seasons: summer and fall. After the cuttings were prepared, they were placed in perforated plastic boxes containing each substrate for rooting, which were placed in a mist chamber under intermittent mist. After 158 days, the following variables were evaluated: proportion of rooted cuttings, cutting survival, leaf retention, number of roots per cutting, root mean length, root dry mass, unrooted cuttings with callus, and the proportion of sprouting cuttings. The use of 5-cm herbaceous cuttings collected in the summer and grown in rice hull optimizes the multiplication of ‘Woodard’ and ‘Briteblue’ blueberry cuttings.

Heterorhizy and fine root architecture of rabbiteye blueberry (Vaccinium virgatum) softwood-cuttings.

All fine root systems consist of individual fine roots. Individual roots have morphological, anatomical, and functional heterogeneity (heterorhizy). Heterorhizy plays crucial roles in plant ecosystems. However, in many species, the heterorhizy and fine root system architecture based on individual root units are unclear. This study investigated heterorhizy along the root system architecture of Vaccinium virgatum Ait (rabbiteye blueberry) softwood-cuttings (propagated from annual shoots in growing season) using protoxylem groups (PGs), a classification according to the number of protoxylem poles, as an indicator of individual root traits. Individual roots of rabbiteye blueberry varied from monarch to heptarch. The frequency of roots with larger number of PGs decreased but those with smaller number of PGs increased from adventitious roots toward lateral roots with different branching levels. This architecture were stable among cultivars, collecting position of the cuttings, or indole acetic acids treatment. Individual root sizes and secondary growth were positively correlated with the PGs. These results indicate that branching itself strongly and broadly controls individual root traits. The individual roots were classified into two types: monarch and diarch roots with small size and lacking secondary growth (thought to be hair roots in core Ericaceae) and triarch or more PG roots with large size and showing secondary growth. These heterogeneous individual roots responded differently to the experimental factors. In particular, elongation of the large roots significantly contributed to increased total root length. These results mean that heterorhizic plasticity is a determinant of root system development and heterorhizic variation exists even under practical cutting condition. In conclusion, we demonstrated heterorhizy of rabbieye blueberry cuttings based on the strong relationships of PG, individual root morphology and growth potential, and root system architecture. This study also supports strong connection between root morphology and functional roles intermediated by the PG.