promising genotypes in the areas where this species grows. The identification of the valuable breeding forms of English walnut among local seed populations facilitates the solution of breeding problems and replenishes the collections of genetic resources with valuable specimens. In this work, we aim to assess the prospects of using new forms to solve breeding problems by means of phenotypic evaluation and molecular genetic analysis. The search for promising forms was carried out in 2022–2023 on the territory of settlements in the different districts of Krasnodar Krai. Economically valuable traits were recorded according to the “Program and Procedure for the Studying the Varieties of Fruit, Berry, and Nut Crops.” In order to assess the level of genetic diversity in the sample of new, promising forms of English walnut, SSR genotyping was carried out using seven microsatellite DNA markers: WGA001, WGA376, WGA069, WGA276, WGA009, WGA202, WGA089. The heterogeneous group of varieties and elite breeding forms of the North Caucasus Federal Scientific Center of Horticulture, Viticulture, and Winemaking, representing the overall diversity of the collection, was also included in the studied sample. The comparison of the polymorphism level in the studied specimens for both individual markers and the entire sample of markers suggests a relatively high heterogeneity of the new, promising forms included in the study. The use of UPGMA, PCoA, and analysis in STRUCTURE software allowed genetic relationships to be established between the new, promising forms and specimens from the genetic collection of the North Caucasus Federal Scientific Center of Horticulture, Viticulture, and Winemaking. The new forms were found not to form a separate cluster and to generally have an intermediate position between the three genotype groups in the gene pool collection. For the new forms, the effect of the Central Asian geneplasm was established, which determines the presence of several valuable breeding traits. Given the data on the genetic diversity of new, promising forms of English walnut relative to the genetically contrasting sample of breeding forms from the collection of the North Caucasus Federal Scientific Center of Horticulture, Viticulture, and Winemaking, it is reasonable to involve new forms in breeding in order to enrich the local English walnut gene pool.

Common plum (Prunus domestica L.) is one of the fruit crops that are particularly difficult to study genetically. Unlike most other species of the genus Prunus, it is a hexaploid species (2n=48) originating from complex interspecific hybridization, and the question of its origin is yet to be conclusively resolved. Presently, several studies are available that examine the phylogeny and systematics of the genus Prunus in general and specifically the speciation of Prunus domestica L., with the use of molecular genetics methods. Although the SSR marker method is widely adopted in the practice of studying the most important stone fruit crops, the polymorphism of SSR loci in Prunus domestica L. is rarely studied in the gene pool. The present study examined the effectiveness of 22 microsatellite (SSR) markers using common plum and cherry plum varieties bred at the Federal Horticultural Center for Breeding, Agrotechnology, and Nursery in order to obtain the genetic profiles of these varieties and develop a variety passport. In addition, this set of markers was used to evaluate the genetic diversity and genetic similarity between the varieties of common plum and cherry plum, as well as remote hybrids obtained using embryo rescue, from the collection of the Federal Horticultural Center for Breeding, Agrotechnology, and Nursery. The screening results obtained for a set of 22 SSR markers using 10 varieties and 19 hybrid specimens revealed a low level of polymorphism detected by this set and a small number of shared alleles. This set of markers was found to be inadequate to fully evaluate our sample in terms of allelic diversity, as well as genetic similarity between parental and hybrid forms. The proportion of unique genotypes that can be identified using these markers amounts to less than 50 %. The large number of overlapping fragment sizes prevents the generation of individual genetic profiles for the varieties. It was found necessary to apply and test additional markers, as well as to develop multiplex sets on their basis, which will form the basis for routine genotyping of varieties. For a more accurate and reliable estimation of fragment lengths and allele sharing, further analysis should be performed using capillary electrophoresis. The work was carried out at the Laboratory of Reproductive Biotechnology of the Federal Horticultural Center for Breeding, Agrotechnology and Nursery in 2022.

The development of stone fruit varieties that meet modern production requirements is a labor-intensive process involving low yields of progeny obtained through controlled intraspecific and interspecific hybridization, which can take up to 25 years. The non-viability of hybrid seeds is caused by the abortion of the embryo that does not have time to complete its morphophysiological development and endosperm abortion in interspecific hybrids. It is possible to preserve hybrids having a unique combination of traits by removing embryos derived from interspecific and intergeneric crossing that are unable to survive in vivo or when using conventional methods for breeding embryos at early developmental stages and placing them under in vitro conditions for further development. On the basis of literary sources, the study aims to analyze growth media, conditions of their application, and time of embryo placement under in vitro conditions designed to preserve immature embryos and create hybrids of stone fruit crops, as well as to identify the most effective in vitro embryo isolation schemes for further use in the breeding process. The analytical review used open sources containing information on the composition of the most commonly used growth media, their compositions, modifications, application conditions, time of embryo placement under in vitro conditions for common peach (Prunus persica (L.) Batsch.), common apricot (P. armeniaca L.), common plum (P. domestica L.), Chinese plum (P. salicina Lindl.), cherry plum (P. cerasifera Ehrh.), sloe (P. spinosa L.), sour cherry (P. cerasus L.), sweet cherry (P. avium (L.) L.), as well as electronic scientific libraries (eLibrary, Scopus, and Google Scholar). The performed analysis of works revealed the following media as optimal for sustaining the development of embryos: common peach – modified growth medium Woody Plant (up to 100 % of preserved embryos); common apricot – modified Monnier (up to 92.4 % of preserved embryos); sour cherry, sweet cherry, plum, and interspecific hybrids – different variants of Murashige and Skoog (over 70 % of preserved embryos). The used modifiers include 6-benzylaminopurine (6-BAP), gibberellic acid (GA), kinetin, peracetic acid, carbohydrates, L-glutamine, iron chelate, ascorbic acid, thiamine, glutamic acid, tryptophan, casein hydrolysate, etc. The time of placement under in vitro conditions varies from 28 days (sour cherry) to 99 days (common peach) depending on the crop. Stratification in the dark at +4…+5 ℃ prior to development increases the yield of viable embryos. The optimal photoperiod for in vitro embryo cultivation ranges from 12 (common peach) to 16 (cherry plum, sour cherry, sweet cherry, and interspecific hybrids) hours. As a result of selection from the fund of hybrids obtained through embryo preservation, one common peach variety (Krymskii Shedevr) and three sweet cherry varieties (Vesnyany Naspivy, Prizerka, and Uslada), recommended for the North Caucasus region, were included in the State Register of Breeding Achievements approved for use; two common plum varieties (Tulitsa and Velichavaya) were included into the Register of Protected Breeding Achievements for the Central Region.

The article examines the effect of jasmonic a cid used at concentrations of 0.1-1.0 mg/L in the longterm continuous in vitro cold storage of clonal apple rootstock explants (54-118, 57-490, 57-545, and MM 106) on their subsequent development on under standard cultivation conditions. A positive effect of jasmonic acid was noted on the preservation of the viable explants of clonal apple rootstocks at all used concentrations over a period of 48-54 months (+3-6 ℃) of continuous cold storage, as compared to the explants cultivated without its application. Different concentrations of jasmonic acid in the cold storage medium were found to have no significant effect on the net reproduction of explants that were subsequently cultivated without jasmonic acid under standard cultivation conditions (+20-22 ℃). However, a significant increase in the length of microshoots (by 1.4-1.6 times) and the average number of leaves per microshoot (by 1.2-1.6 times) was observed in all studied forms of clonal apple rootstocks on growth medium with a jasmonic acid concentration of 1.0 mg/L. Subsequently, these explants exhibited no delay in vegetative development in vitro as compared to the explants that did not undergo cold storage (control). Jasmonic acid addition to the growth medium for long-term continuous cold storage at can be recommended as a way to improve the preservation of explants when clonal apple rootstock collections are stored for long periods of time in in vitro culture.

The article characterizes a kiwifruit cultivated in the subtropical zone of the Black Sea coast in Krasnodar Krai. Scientists are currently interested in kiwifruits that contain a considerable amount of vitamins, specifically vitamin C. The present study aims to examine the biochemical composition of a kiwifruit having a high nutritional value, as well as vitamins and useful elements necessary for the human body. These studies on the plantings of Actinidia deliciosa have been conducted at the Adler Experiment Station of the Federal Research Center N. I. Vavilov AllRussian Institute of Plant Genetic Resources (Krasnodar Krai) since 2017. The growing area is 5×4 m, amounting to ha. The crop is grown in alluvial grassland low-humus soil. The biochemical composition of fruit was analyzed at the Department of Plant Physiology and Biochemistry of the Subtropical Scientific Centre of the Russian Academy of Sciences. The results of biochemical studies (2017–2018) evaluating the fruit of Actinidia delicata are presented. The study included five kiwifruit varieties: ‘Hayward’ (late ripening period), ‘Allison’, ‘Abbott’ (early ripening period), ‘Bruno’, and ‘Monty’ (average ripening period). The maximum sugar amount of 9.67–10.92 % was observed in the fruit of ‘Monty’, ‘Bruno’, ‘Abbott’, and ‘Allison’ varieties, while the minimum amount was found in ‘Hayward’ (7.79 %). In the experiment, the titratable acidity amounted to 0.75–0.82 %. The sugar-acid ratio was found to be within the range of 9.50–14.99 RU. The best varieties in terms of the content of extractive substances in fruits were ‘Abbott’ and ‘Bruno’. A high ascorbic acid content of 148–171 mg/100 g was observed in ‘Hayward’, ‘Abbott’, and ‘Bruno’ varieties, while a low content of 119.50–125.50 mg/100 g was noted in ‘Monty’ and ‘Allison’ as compared to other varieties. The quantitative content of dry matter was found to be within 15.04–16.00 %, which indicates good transportability, storability, and shelf life of kiwifruit as long as the necessary rules are followed.

In addition to ascorbic acid and phenolic compounds, yellow, orange, and bright red fruit and berry crops contain carotenoids—antioxidant substances that have a positive effect on the human body. The article presents the results of studying the content of carotenoids in light-colored berry fruits: sea buckthorn, gooseberry, and red currant. Sea buckthorn was found to be the leader in the accumulation of this biologically active substance. In gooseberry and red currant, which have light-colored fruits, carotenoids are found in small amounts. The average carotenoid content is as follows: sea buckthorn – 4.98 ± 0.49 mg/100 g; gooseberry – 0.68 ± 0.07 mg/100 g; red currant – 0.33 ± 0.04 mg/100 g.

The average content of carotenoids accumulated in sea buckthorn fruits varies significantly from 1.69 (Zheltoplodnaya) to 10.59 mg/100 g (ELS 8-51), with a variation interval of 8.90 mg/100 g and a variation coefficient of 46.0%. Of the studied varieties, elite and selected forms of sea buckthorn, specimens having a carotenoid content of over 6.00 mg/100 g in fruits were identified: Karamelka, Kenigsbergskaya, Podarok Chernozem’yu, Syurpriz Baltiki, ELS 8-51, and OS 8-51-44-20. In 31.8% of variety specimens, the carotenoid content in fruit was lower than the variety average (below 3.50 mg/100 g)– from 1.69 to 3.46 mg/100 g. Of breeding interest is the selected elite young plant 8-51 that accumulates the maximum amount of carotenoids in fruit (10.59 mg/100 g) and exhibits the studied trait stability (V = 10.9%). Gooseberry and red currant are of no breeding interest as sources of carotenoids.

The article presents the results of an analysis conducted from 2022 to 2023 to assess the quality of modern neural network models of apple fruit identification in tree crowns shown in images. In order to conduct the studies on identifying the best detector, the following neural networks were used: SSD (Single Shot MultiBox Detector), YOLOv4 (You Only Look Once, Version 4), YOLOv5, YOLOv7, and YOLOv8. The performance of the considered models of apple fruit identification was assessed using such binary classification metrics as precision, recall, accuracy, F-score, and AUC-ROCTotal (area under the curve). To assess the accuracy in predicting apple fruit identification, the mean absolute percentage error (MAPE) of the analyzed neural network models was calculated. The neural network performance analysis used 300 photographs taken at an apple garden. The conducted studies revealed that the SSD model provides lower speed and accuracy, as well as having high requirements for computing resources, which may limit its use in lower performance devices. The YOLOv4 model surpasses the YOLOv5 model in terms of accuracy by 10.2 %, yet the processing speed of the YOLOv5 model is over twice that of the YOLOv4 model. This fact makes the YOLOv5 model preferable for tasks related to real-time big data processing. The YOLOv8 model is superior to the YOLOv7 model in terms of speed (by 37.3 %); however, the accuracy of the YOLOv7 model is 9.4 % higher. The highest area under the Precision-Recall curve amounts to 0.94 when using the YOLOv7 model. This fact suggests a high probability that the classifier can accurately distinguish between the positive and negative values of the apple fruit class. MAPE calculation for the analyzed neural network models showed that the lowest error in apple fruit identification amounted to 5.64 % for the YOLOv7 model as compared to the true value determined using the visual method. The performance analysis of modern neural network models shows that the YOLO family of neural networks provides high speed and accuracy of object detection, which allows them to operate in real time. The use of transfer learning (tuning of only the last layers to solve highly specialized problems) to adjust the performance of models for different apple fruit varieties can further improve the accuracy of apple fruit identification.