Clonal Rootstocks Research Articles

Growth of unpruned June budded ‘Chandler’ walnut on clonal Paradox rootstock

Growth of unpruned June budded ‘Chandler’ walnut on clonal Paradox rootstock

An assessment of clonal rootstocks of an apple tree in conditions of the steppe zone in the Trans-Volga-Ural region

Small stature forms of clonal rootstock in combination with recognized and appreciable varieties promote to increase productivity in one and half-two times from a unit of the area. New clonal rootstocks are characterized by increased winter- and drought-resistance, enabling the growth of rootstocks’ adaptiveness to the Trans-Volga-Ural region’s extreme conditions. Conditions of the region are characterized by low temperatures in the winter to −40 – −42°C. A deficit of precipitation and high temperatures to + 40-+ 42°C is noticed in the summer. Our research aims to study the adaptive ability of groups of clonal rootstocks of an apple tree above 30 forms of selection in Central Russia, Povolozhie, and foreign countries. Laboratory-field methods “Program and methodology of selection of fruit…” (1999) were used to estimate the adaptiveness of rootstock forms, including drought-resistant kinds. Forms: 71-3-195, MM 106, Baba-arabskaya Adzhi, Ural 5, Ural 3, elite forms 6 – 9 H, 5-4-13 are characterized by high preservation (80-90%) among clonal rootstocks for the years of the study. Forms: Ural 5, 62-223, 54-118, Ural 2, elite forms 4-5, 4-19-3, 76-23-2, К-2, 71-7-22, Don 70-456 are characterized by drought-resistance. Rootstocks of semi dwarves: 64-134, Ural 6, Ural 2, elite forms 5-4-13, 4-19-3, 5-19-1, dwarfish forms are: 71-7-22, 58-238, 64-134, 62-14, К-2, Don 70-52, have received 4-5 points according to the plantation state. All kinds listed above showed high adaptive ability in extreme conditions of the Trans-Volga-Ural region and were initial material to establish intensive plantings.

Thirty-three half-sib apple clonal rootstocks tolerant to crown rot produced in a 14-year pathology breeding program

Thirty-three half-sib apple clonal rootstocks tolerant to crown rot produced in a 14-year pathology breeding program

Promising drought-resistant and heat-resistant species and varieties of the genus Malus Mill. for creation of sustainable agrocenoses in the Trans-Volga-Ural region steppe

The stability and productivity of horticultural agrocenoses depend on the adaptation of fruit plants to climatic and landscape-ecological conditions. To form profitable fruit plantings in the Trans-Volga-Ural region, it is necessary to select varieties with high potential resistance to drought. The purpose of our study is to study the drought- and heat resistance of species and varieties of the genus Malus Mill growing in the study area. To estimate drought-resistance, we identified: the water content of leaves, water deficit, the water-retaining ability for 2 – 6 hours, the water loss on average for 1 hour, and heat-resistance. 180 samples of the genus Malus kinds, sorts, and varieties were the study objects for two years.Stress climatic factors were not noticed in 2019; therefore, most of the studied samples received a high assessment of relative drought-resistance. M. fuska, M. zumi, M. kaido., M. baccata (Dubki), and clonal rootstocks Ural 1, Ural 5, Ural 8, Arm 18, OB 3-4, OB 4-3, 54-118 and others were among the most drought-resistant species and varieties of the genus Malus in 2019. The vegetation period of 2020 was abnormally hot and dry. According to the water content in tissues, many of the leading sorts and forms of 2019 showed lower results in 2020. M. denticulata, M. mandzschurica, M. sikkimensis, M. turkmenorum №4, M. turkmenorum №5, M. purpurea, M. zumi, 70-20-20, Ural 7, Volga 12. were noticed among the most resistant representatives of the Malus family in 2020.

COMPARATIVE ESTIMATION OF SCION-STOCK PLUM COMBINATIONS IN THE VORONEZH REGION

In the pomological garden on the territory of the Voronezh State Agrarian University named after Emperor Peter I, scientific research is conducted on the study of graft — rootstock combinations of plum selection of the Department of Fruit and Vegetable Growing and research institutions of the country. Plum plantations are represented by varieties of domestic plum ( Prunus domestica L.): Voronezhskaya compotnaya, Bolkhovchanka, Universalnaya and Utro, grafted on seed — seedlings of cherry plum (control) and clonal rootstocks: OP-23-23, SVG-11-19 and VSV-1. The research was carried out in the period 2017–2019 in a garden planted in the spring of 2013 according to the 6×4 m scheme. The highest indicators of crown habit and yield, ranging from 8.8 for the Bolkhovchanka variety to 12.7 t/ha for the Universalnaya, were observed in trees grafted on seed rootstocks (k). At the same time, the quality of fruits in such plantings was inferior to the graft-rootstock combinations on clonal rootstocks. The most restrained parameters of the crown and the minimum yield (5.1-6.3 t/ha) were observed in the studied varieties on the low-growing rootstock VSV-1, and the volume of the crown, depending on the variety, changed slightly and was in the range of 1.7-2.8 m 3 . On medium-sized rootstocks of OP-23-23 and SVG-11- 19, the maximum yield (7.7-8.9 t/ha) was determined for the Bolkhovchanka, Universalnaya and Utro, and the minimum yield was for the Voronezhskaya compotnaya — 6.3-7.3 t/ha. Analyzing the suitability of graft-rootstock plum combinations for compacted plantings by the value of specific productivity, it can be recommended on medium-sized rootstocks OP-23-23 and SVG-11-19 for varieties Bolkhovchanka and Utro (6.5-7.7 kg/m 3 ), on the rootstock SVG-11-19 — Universalnaya (6.6 kg/m 3 ) and the studied varieties of low-growth rootstock VSV-1 (5.1-8.5 kg/m 3 ).

Chemotherapy of apple shoots in vitro as method of viruses eradication

The article presents the results on the viruses eradication from in vitro shoots of varieties and clonal rootstocks of apple (Malus domestica Borkh.) using chemotherapy and obtaining healthy super-elite planting stocks. Ribavirin at concentrations of 75 and 100 mg/L caused severe in vitro shoot necrosis. Three subcultures on Murashige-Skoog medium with 50 mg/L ribavirin was efficient for elimination of Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), and Apple mosaic virus (ApMV) from in vitro shots of Malus varieties and clonal rootstocks. A virus-free in vitro collection (42 accessions) was established, which was used for create a cryobank of shoot tips at -196°C and to obtain virus-free planting stocks. The percentage of in vitro shoots rooting ranged from 50% to 90%. The survival rate of in vitro shoots rooted in the soil substrate is more than 90%. Keywords: apple, chemotherapy, in vitro culture, ribavirin, virus-free planting stocks

Adventitious rooting of cultivars and clonal selections of Prunus spp. rootstock under intermittent mist system

To reduce peach tree losses due the Peach Tree Short Life (PTSL), the main research line in Brazil is to select tolerant rootstock and perpetuate it by cloning methods. The objective was to evaluate adventitious rooting capacity of softwood cuttings of three cultivars and several clonal rootstock selections of Prunus spp., under intermittent mist system. Two trials were conducted and ‘Capdeboscq’, ‘Okinawa’ (P. persica) and ‘Sharpe’ [‘Chickasaw’ (P. angustifolia Marsh.) x Prunus spp.] were used as reference cultivars. After 53 days (trial 1) and 72 days (trial 2) from the cutting setting, we conclude that softwood cuttings under intermittent mist system are a feasible way to propagate peach rootstock selections of 2010/2011 PTSL selection cycle. Root quality was satisfactory in most selections, with high percentages of cuttings suitable for transplanting and excellent root number and root length. OS-GRA-10-17, VEH-GRA-10-31, VEH-GRA-10-32, VEH-GRA-10-37 and VEH-GRA-10-38 selections had the highest mortality and the lower percentages of live rooted cuttings. The ease of vegetative propagation must be taken into account in more promising rootstock.

In vitro multiplication and rooting of GF677 rootstock

Purpose: Micropropagation of GF677 rootstock, the most widely clonal rootstock used in peach orchards, is an important method for large-scale production of disease-free plants. In this research, effects of media, plant growth regulators and carbohydrates in order to optimize the efficient micropropagation protocol of GF677 rootstock has been investigated. Research method: In vitro shoots were multiplicated on MS, WPM and DKW media supplemented with 0, 0.5, 1, 2 mg L-1 BA. Proliferated shoots were rooted on MS, WPM and DKW media containing 0, 0.5, 1, 2 mg L-1 IBA. In another experiment, the effect of carbohydrate type was investigated. Findings: High shoot number and node number as well as shoot fresh weight were achieved with shoot tips when cultured on MS medium supplemented with 1 or 2 mg L-1 BA. The highest percentage of rooted shoots was obtained on MS or WPM media supplemented with 1 or 2 mg L-1 IBA. Maximum root number was regenerated on WPM medium containing 1 mg L-1 IBA. Sorbitol was found to be more effective carbon source on shoot multiplication than sucrose, while the highest average of root number and root length were observed in the medium containing sorbitol and sucrose medium, respectively. Survival rate during the acclimatization in the greenhouse was 67%. Limitations: Plant acclimatization needs to be studied for commercial production. Originality/Value: This protocol has proven useful for micropropagation of GF677 rootstock.

Study of cherry agrobiological and biochemical values depending on the breeding method

In 2018–2020, in the Federal Research Centre of Horticulture in the Leninsky district of the Moscow region, a research study into the growth, production and biochemical processes of ungrafted and grafted cherry trees was performed. The planting plan was 5×2.5 m, the age of the trees — 17-19 years. Three varieties of cherries (Rusinka, Volochaevka, Apukhtinskaya), grafted on clonal rootstock (AVCH-2, Moskoviya Izmailovskiy) and own-root, propagation-grown by herbaceous cuttings, were selected as the study objects. Biochemical studies involved determining the total antioxidant status of the alcoholic extract, the chlorophylls (a and b) and carotenoids content, the total of phenolic compounds, rutin and quercetin in the leaves. The study aimed to assess the agrobiological and biochemical parameters of grafted and own-root cherry varieties and to identify the optimal growing technique for promising ones. It was found that the variety, rootstock and breeding method influenced the growth and development of cherry trees. The linear and radial growth improved for the trees grafted on the AVC-2 and Moskoviya rootstocks and the height and crown volume thinned for the own-root trees and in those grafted on the Izmailovskiy rootstock. Depending on the variety, stock and growing technique of seedlings, the productivity of trees ranged from 3.5 (Rusinka, own-root) to 11.6 kg/tree (Apukhtinskaya, own-root). The advantage of own-root trees compared to grafted ones was revealed for Apukhtinskaya and Volochaevka varieties. The Rusinka variety showed the highest productivity when grafted on the Izmailovsky rootstock (5.5 kg/tree). To increase the yield per garden when cultivating the Apukhtinskaya and Volochaevka varieties, it is beneficial to use own-root seedlings grafted on the Moskoviya and Izmailovskiy rootstocks. For the Rusinka variety, the optimal result can be achieved when growing seedlings grafted on the Izmailovsky rootstock. The biochemical studies allowed the influence of rootstock on the photosynthetic, antioxidant systems and the synthesis of phenol compounds in the cherry leaves to be determined. It was shown that the antioxidant activity and the accumulation of phenol compounds in the leaves were the highest for the own-root plants of the most winter-hardy Rusinka variety and the Rusinka/Izmailovskiy graftedrootstock combination. The chlorophyll and carotenoid contents were the highest in the leaves of the Apukhtinskaya variety own-root trees, Apukhtinskaya/Izmailovskiy and Rusinka/Izmailovskiy grafted-rootstock combinations with increased productivity. Notably, the biochemical values decreased for all varieties grafted on the AVC-2 rootstock.

Clonal selection in cacao based on early yield performance of grafted trees.

An experiment with 45 Theobroma cacao L. clones grafted onto a common rootstock was established between September 1991 and November 1997 to determine the yield potential of trees selected from interclonal families. Scionwood of 40 promising trees selected from among 1,320 trees, representing five families and three locations "m Puerto Rico, were patch bud grafted onto the rootstock clone EET-400. Additionally, scionwood of five of the eight parental clones involved in the combination of the families was also grafted onto the same rootstock. The 45 treatments were arranged in a randomized complete block design with six replications, each containing two experimental trees per replication. The trees reached full production in 1994, during the third growing year. Between 1994 and 1997 the mature pods were harvested, and the dry bean weight and pod index were determined. The means of the 40 grafted selections were compared with the combined means of five parental clones or to the mean of their highest yielding parent (P < 0.01). At the termination of the experiment in November 1997, only nine of the grafted clones significantly outyielded their parents, with a mean production of 2,170 kg/ha/year of dry beans. This finding indicated that fewer than 1% of the trees in the original five-family population were exceptionally superior yielders. Five of the nine superior yielding clones also had a significantly higher pod index. None of the 16 clones representing families IMC-67 X SCA-12 and IMC-67 x UF-613 performed as superior yielders. We concluded that either one or both parents involved in these interclonal crosses lack combining ability and may be excluded from cacao improvement programs, in addition, we found a direct relation between high pod index and superior dry bean weight in the progeny of family SCA-6 x EET-62.

PECULIARITIES OF BIOECOLOGY OF HARMFUL VIRUSES IN APPLE PLANTS

The prevalence of harmful viruses of Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV), depending on the location, age, and varietal composition of plantings, was studied. Sandwich ELISA was used in serological tests. Diagnostic kits from «Loewe» (Germany) were used for the analyzes. Leaves were taken as samples. The results of the analysis were recorded using a «Stat Fax 2100» photometer. On apple varieties and clonal rootstocks, the frequency of viruses was 36-54 % and 24 %, respectively. In the Moscow region, the ASPV virus (23 %) prevailed, in the Ryazan region — ApMV (33 %), in the Yaroslavl region — ACLSV (54 %). At the end of the 20th century, the ACLSV virus was more often detected on the apple tree, and in the last decade, we have established an increase in the infection of this crop with the more harmful ASPV and ASGV viruses. The highest prevalence of latent viruses was noted on old domestic apple varieties and foreign varieties (50 % each). A tendency to an increase in the indices of infection with most of the studied viruses was revealed with an increase in the age of trees. In apple trees of old age (over 20 years), the indices of infection with the ASPV virus increased by 25 %, ASGV — by 20 %, ACLSV — by 43 % compared to middle-aged trees (8-10 years). Apple plants of 15 varieties and apple rootstocks of 2 forms 54-118 and 57-490 were found free from the main harmful viruses

Growth and Nutrients Uptake in Commercial Pear Cultivars on Seedling, Pyrodwarf® and OH × F69 Rootstocks

Pyrodwarf and OH × F69 rootstocks are the main clonal rootstocks for pear trees in Iran. This research was conducted to compare growth and nutrient uptake in different commercial pear cultivars including; Louise Bonne, Dargazi and William`s Duchesse on Pyrodwarf, OH × F69 and Dargazi seedling rootstocks in two years in the nursery. Both clonal rootstocks inducted higher growth in cultivars. Cultivar Louise Bonne had the highest growth on Pyrodwarf rootstock. Calcium content varied from 1.4% to 1.5%, but nitrogen, phosphorus, potassium and manganese showed higher variation, and the highest content of these nutrients were observed in cultivar Dargazi on Pyrodwarf rootstock. The lowest and the highest variations were observed in zinc and iron content, respectively. In addition, about 30% of total iron of the leaves was active iron, indicating high level of active iron in pear in comparison with other fruit tree species. In all graft combinations, variation in micro and macro nutrients contents were in optimum range. Comparison of nutrient contents with active lime level in soil indicated that the range of 10-15% active lime in soil would not hinder growth and nutrients uptake of plants.

In vitro Effect of Replacement Mineral Salts of Trace Elements with P-containing Chelates to Improve Rooting of Cherry Rootstock (cv. VC-13)

In this paper, we studied the effect of modified culture medium based on Murashige and Skoog (Murashige T. Skoog F., 1962) on the in vitro rhizogenesis of clonal rootstock of stone cultures - VC-13. For the first time, the nutrient medium was modified with complexes of all incoming trace elements based on a phosphorus-containing ligand of the bisphosphonate class. The effect of 3 levels of concentrations of chelated trace elements was studied: 1.25, 2.5 and 5 ml/l without the use of increased doses of BMI, and a comparative analysis was carried out in comparison with the modification of trace elements based on EDTA. The maximum effect – 100% rooting after 30 days of subcultivation was found at a concentration of chelated trace elements of 5 ml/l. When modifying EDTA, rooting did not occur. Also, the modification of the nutrient medium by phosphorus-containing complexes contributed to a change in the nature of the formation of the root system of micro-gears. Micro-plants had from 3 to 6 short strong roots, convenient for washing from the nutrient medium and then planting at the stage of adaptation to non-sterile conditions. Repeated tests of the effect of culture medium modification on rhizogenesis in vitro on a larger scale confirmed the high efficiency of this approach. The rooting rate of micro-gears of the VC-13 clone rootstock was more than 80%. The results obtained allow us to conclude about the key role of the nature of the chelating agent.

Assessment of fire blight resistance in apple clonal rootstocks using molecular markers

Background. Clonal apple rootstocks are one of the main components of intensive gardening. The degree of rootstock damage by fire blight affects the resistance of the variety–rootstock combination. The paper presents a study on marking quantitative trait loci (QTL) of resistance to fire blight Erwinia amylovora in clonal apple rootstock.Materials and methods. A collection of 20 rootstock forms was analyzed. For the study, SCAR markers GE-8019, AE10-375 and microsatellite marker CH-F7-FB1 were used.Results. Polymorphism was observed for all three markers, and their various combinations in one genotype were revealed. It was previously noted that genotypes that carry all three markers were more resistant than those that lack them. The presence of all three markers was observed only in forms 62-396 (В10), 16-1 and 2-9-102. The other genotypes did not have the GE8019 marker. The AE10-375 marker was identified in eight clonal rootstocks. Microsatellite marker CH-F7-FB1 was present in all tested rootstocks. However, polymorphism was detected there. Most genotypes had a 174 bp fragment, but a 210 bp fragment was identified in two of the 20 forms. Clonal rootstock 70-20-21 proved heterozygous for this marker. The analyzed collection also included samples that had only the microsatellite marker: G16, Malysh Budagovskogo, Paradizka Budagovskogo (B9), 54-118 (В118), 57-491, 70-20-20 (В119), 70-20-21, 71-7-22, 76-3-6, 83-1-15, 87-7-12, and 2-12-10. The study of rootstock forms on the basis of resistance to metabolites of the fire blight pathogen was carried out under laboratory conditions using the E. amylovora culture filtrate in vitro on leaf explants. Most of the studied genotypes had different combinations of markers. However, the experiments showed that forms 62-396 and 14-1 with two out of three markers (AE10-375 and CH-F7-FB1) phenotypically manifested the trait of resistance to metabolites of E. amylovora.

The role of Prunus cerasifera Ehrh. in the origin, evolution and improvement of stone fruit cultivars

At Krymsk Experiment Breeding Station of VIR, as a result of collecting, studying, and selective use of myrobalan plum genetic diversity, the intraspecific taxonomy of the species Prunus cerasifera Ehrh. was clarified. Donors of traits significant for breeding were identified and, with their use, adaptable cultivars of myrobalan plum, Russian plum and clonal rootstocks of stone fruit plants were developed.Intraspecific classification of P. cerasifera is proposed, with the identified subspecies:subsp. cerasifera (typical myrobalan plum);subsp. orientalis (M. Pop.) Erem. et Garcov. (Oriental myrobalan plum);and subsp. macrocarpa Erem. et Garcov. (large-fruited myrobalan plum).Within subsp. P. cerasifera subsp. macrocarpa, varieties were identified:var. macrocarpa (typical, or Krymsk);var. georgica Erem. et Garcov. (Georgian);var. iranica (Koval.) Erem. et Garcov. (Iranian);var. nairica (Koval.) Erem. et Garcov. (Armenian);var. pissardii Carr. (Pissard);and var. taurica (Kost.) Erem. et Garcov. (Taurida).The participation of myrobalan plum in the origin of spp. P. brigantiaca Vill., P. cocomilia Tem., and P. spinosa L. was traced. Involvement of large-fruited myrobalan plum in hybridization with blackthorn contributed to the manifestation of an exceptional polymorphism among the varieties of the hybridogenic species P. domestica L. (P. cerasifera × P. spinosa). As a result of hybridization between myrobalan plum and Chinese plum varieties, a new cultigen species emerged – Russian plum (× P. rossica Erem.). By now, 127 cultivars of this species and 7 clonal rootstocks for stone fruit crops have been developed. These cultivars and clonal rootstocks are zoned for Russia and a number of other countries.

Rooting dynamics of Prunus minicuttings

There is a lot of information on the peach tree culture. However, it still lacks an efficient system for the seedlings production that guarantees genetic and sanitary quality, resulting in high productivity. The objective of this study was to determine the optimum rooting time for Prunus minicuttings to obtain clonal rootstocks. The installation of an experiment happened to check the viability of propagation by herbaceous minicuttings of the rootstocks, using Flordaguard, Okinawa, and the Capdeboscq canopy cultivar on different evaluation days (20, 30, 40, 50, and 60 days). Each treatment consisted of four replications of 20 minicuttings. The experiment consisted of preparing herbaceous minicuttings of approximately three to five centimeters, containing two buds and a leaf cut in half, with a bevel cut at the apex and transverse at the base of the mini-pile and two superficial lesions on opposite sides of the base. Later, they were immersed in a solution of 2000mg L-1 of indolebutyric acid (IBA) for 10 seconds and placed in transparent plastic containers containing medium-granulated vermiculite, previously moistened. Afterward, they were placed in greenhouses under controlled temperature. At 50 days, the highest percentage of rooting observed in the cultivar was Flordaguard (70%). The other cultivars resulted in a lower percentage of rooting on different evaluation days.

Optimization of the technology of clonal micro-propagation of cherry varieties and clonal rootstocks at the initial stages of in vitro cultivation

The article presents the results of studying some components of the in vitro technology of clonal rootstocks and common cherry varieties, which allow to increase the efficiency of its application to the tested cherry varieties and clonal rootstocks. Differences in the viability and intensity of the development of clonal cherry rootstocks and varieties explants depending on the timing of their introduction into the crop, the characteristics of genotypes and the composition of nutrient media were established. The influence of nutrient medium composition, content and ratio of growth regulators and genotype in it on the multiplication coefficient of cherry varieties and clonal rootstocks was revealed. The optimal calendar dates for the introduction of cherry varieties and clonal rootstocks explants into the crop in vitro for the autumn-winter-spring period are established. The optimal composition of the culture medium for the initial stages of clonal micropropagation is established. The reproductive potential of some clonal rootstocks and cherry varieties in crop in vitro was revealed.

Перспективные клоновые подвои косточковых плодовых культур селекции Крымской опытно-селекционной станции

The authors present data of the studying of promise stone fruit crops clonal rootstocks bread at the Krymsk FBS in the nursery and orchard. Besides, their ability of cuttings rooting, compatibility with perspective stone fruit crops cultivars were researched as well as suitability for growing in different regions of the country. The prospect of applying industrial the intensive technologies of the sweet cherry cultivation in the south of Russia, became possible in the recent years in connection with the creation of new high-quality and productive varieties and inland low-growing clonal rootstocks, more adapted to the unfavourable environmental conditions, which often occur here. The low-growing rootstocks obtained recently at the Krymsk FBS concerning their characteristics can compete with the well – known foreign semi-dwarf ones, such as Gizela 5, Gizela 6, Inmil, Piku 1, Piku 3, Piku 4. The plum and peach dwarf rootstock Upriamiets as regards vigour similar to BBA 1, reduces the growth of the trees grafted on it by 50-60 %, is characterized with early maturity and compatible with all the varieties of the tested above mentioned crops. RVL 9 is a medium-sized and Rulan 8 semi-dwarf sweet cherry rootstocks. They have a very strong root system that provides good trees anchoring in the orchard and form root sprouting when have non-considerable mechanically damage only. Sweet cherry trees on RVL 9 are by 25-30 % and on Rulan 8 35-40 % a size smaller as compared to those grafted on cherry seedlings. The fruiting begins in the third year, the yield is high. The propagation using hard-wood cuttings, which does not require special structures, has significant advantages over others methods. It ensures the high reproduction coefficient at minimum expenditures, including manpower. Therefore just this method is the most perspective for utilizing in production. Among the zoned sweet cherry clonal rootstocks easily propagate only VSL 2, VSL 1 and L 2 are propagated easily when hard-woody cuttings are applied. The study of RVL 9 and Rulan 8 as for their ability of reproduction using the above mentioned cuttings has shown that in this respect they are close to the control standard clonal rootstock VSL 2. As a result of the breeding work which we have carried out, the clonal rootstocks Upriamiets, RVL 9 and Rulan 8 have been entered in the State Register of Breeding Achievements admissed for the application in Russian Federation.

Study of the water regime dynamics of cherry in the summer period

The research was carried out on the basis of the VNIISPK Laboratory of Fruit Plant Resistance Physiology in 2019-2020. The research object was the Novella cherry variety on the clonal rootstocks of the institute selection. The purpose of this research is to study the dynamics of the water regime of the Novella variety on clonal rootstocks and to identify the most adapted scion-rootstock cherry combinations. A strong relationship was determined between the cherry leaves hydration and the average daily air temperature (r = 0.99). During the ripening period of the fruits of the Novella variety scion-rootstock combinations, the maximum decrease in the total water in the leaves was recorded. The water content decreased as the age of the leaves increased. The decrease in water content in the Novella scion-rootstock combinations was accompanied by an increase in the dry matter content in the leaf tissues. There was a strong relationship between the dry matter accumulation in the leaves and the average daily air temperature (r = -0.99). The water deficit in the leaves depended on the hydrothermal regime of the summer period. Correlation (r = 0.76) between the leaves water deficit and the average daily air temperature, the amount of precipitation (r = -0.77) and the HTC (r = -0.83). The highest water deficiency indicator in leaves was found during shoots growth and formation of the leaf apparatus in the Novella variety on clonal rootstocks. The conducted studies allowed to identify adapted scion-rootstock combinations of Novella/Rubin, V-2-180, 74340, 74336, 74332, which, against the background of water content decrease and dry matter accumulation were characterized by the lowest water deficit of leaves in the summer.

Anticipating the formation of guava seedlings using mini-grafting onto smaller-diameter clonal rootstocks

Abstract The production of grafted seedlings requires longer periods of time. The technique of mini-grafting onto rootstocks previously obtained from herbaceous cuttings can guarantee the genetic fidelity of scion and rootstock and allows grafting onto smaller-diameter stems, accelerating the time required to obtain seedlings. The aim of this study was to anticipate the formation of ‘Paluma’ guava seedlings grafted onto clonal rootstocks with smaller-diameter stems. Treatments consisted of grafting onto rootstocks with five stem diameter classes. The experimental design was randomised blocks with three replicates and five seedlings per plot. Rootstocks were produced from cuttings of herbaceous branches of mother plants originating from crossing between P. guineense and P. cattleianum. Mini-grafts were obtained from a clonal ‘Paluma’ guava mini-garden . Seedlings grafted onto rootstocks with stem diameters from 3.7 to 10.3 mm presented the same success rate however the greatest seedling vigour was observed when grafted onto larger-diameter rootstocks. Grafting success and seedling height show that mini-grafting onto clonal rootstocks with diameters from 3.7 to 5.5 mm allows producing seedlings suitable for transplanting 300 days after cutting.