GENETIC SOURCES FOR BREEDING BUSHY AND SHORT-VINE WATERMELON CULTIVARS

Background. When studying the collection of watermelon, it is important to disclose its genetic potential by identifying spontaneous mutations, using its accessions in crosses, and analyzing inheritance of its main traits in hybrids. One of the priorities in watermelon breeding is to develop and produce genetic sources of bushy and short-vine forms with stable manifestation of their morpho-biological characters under various environmental conditions.Material and methods. Accessions from the watermelon collection (local landraces, commercialized and promising cultivars, hybrids and lines obtained in the process of work) of diverse ecogeographic groups served as the material for this research. Description of morphological characters and assessment of economically useful ones were based on the guidelines for studying and maintaining the cucurbit collection and the guidelines for cucurbit crop breeding, both developed by VIR.Results. Variability and inheritance of the bushiness and short vine characters were studied in watermelon accessions according to the features of their growth and development. The habitus of the bushy forms is shaped by the length of stems (0.8– 1.2 m) and very short (2–3 cm) internodes. Short-vine plant stems are 1.3–1.5 m long. Short-vine plants in the early period of development distinctly stand out for their compact bush, if compared with long-vine forms. Short vines are developed due to short internodes (4–5 cm) and a smaller number of lateral shoots.Conclusion. Many years of studying the watermelon collection in the field resulted in identification of promising genetic sources for the breeding of bushy and short-vine cultivars: bushy dissected-leaf lines (KRL) – KRL 694, KRL 656, KRL 376 and KRL 394; bushy entire-leaf lines (KTsL) – KTsL 760/13; yellow-green bushy dissectedleaf lines (ZhZKRL) – ZhZKRL; short-vine watermelon lines (KPL) – KPL 774 and KPL 368. The developed lines differ in morpho-biological and economically useful characters (yield,fruit quality, growing season duration, etc.). They possess resistance to diseases (fusarium wilt and anthracnose) and environmental stressors. The lines are offered for use in the breeding of new bushy and short-vine cultivars and improvement of the existing ones, with various combinations of morpho-biological and economic traits. Brief descriptions of main economically valuable characters of the breeding lines are presented

DIVERSITY OF THE PUMPKIN COLLECTION AND ITS HEREDITARY POTENTIAL. RESULTS AND PROSPECTS OF BREEDING PRACTICE

Background. Pumpkin is an important food, feed and medicinal crop. It is widely used by national cuisines in many countries and utilized as raw material for canning industry and in pharmacy to prepare drugs. The Kuban Experiment Station of VIR, where the collection of pumpkin genetic resources is maintained and regenerated for long-term storage in the genebank, conducts comprehensive research work to analyze the genetic diversity of pumpkin accessions and disclose the potential of its hereditary variation.Objective. The aim of this study was to screen various species from the global pumpkin collection and identify sources of traits valuable for breeders in order to develop promising cultivars and hybrids.Materials and methods. The pumpkin collection was studied and the breeding work was performed using the guidelines worked out by VIR’s scientists. The work included botanical description, study of variability and inheritance of traits, hybridization, inbreeding, mutagenesis, and different selection techniques (individual, group, individual/ family, and mass selection). In the first stages of the study, inbreeding was employed to select best plants from the collection in order to set up a trait-specific collection and incorporate its accessions into the hybridization process. Self-pollination was usedfor several years to obtain self-pollinated lines, sufficiently uniform in the selected trait. The hybrid progenies from crosses between parental forms were analyzed to throw light on the inheritance of major traits and their genetic control. The accessions were assessed for their earliness, productivity and quality. Evaluation of disease resistance was carried out in the field under natural infection pressure.Results and discussion. Targeted breeding efforts resulted in releasing cultivars of Cucurbita pepo L., C. maxima Duch. and C. moschata Duch. ex. Poir. having different maturation schedules and approved for cultivation in various regions of Russia: ‘Kustovaya oranzhevaya’, ‘Lechebnaya’, ‘Kustovaya zolotaya’, ‘Malyshka’, ‘Matreshka’, ‘Krasavitsa’, Zimnyaya sladkaya’, ‘Zhemchuzhina’, ‘Yantarnaya’ and ‘Mariya’. These cultivars are in demand among both agricultural producers and individual growers. New sources of valuable morphobiological and agronomic characters have been identified as useful for modern plant breeding trends: KL 625, ZhZM 692, L-180, L-193, KPL 168, KL 568 and KL 570. New bushy lines of C. maxima and C. moschata selected from cultivar and hybrid populations are now tested in an elite test nursery in order to submit the best of them to the State Variety Trials

Identification and development of source material for breeding early bushy and short-vined cultivars of <i>Cucurbita moschata</i> Duch. ex Poir.

Background. There are three species cultivated in Russia: Cucurbita pepo, C. maxima, and C. moschata, the latter being the most thermophilic among them. Cultivars of C. moschata are grown in southern regions, where a growing season of no less than 110–130 days is required. C. moschata has no bushy cultivars suitable for cultivation. The aim of this study was to search for, identify and develop source material of C. moschata for breeding early-ripening bushy and short-vined cultivars.Materials and methods. Accessions from the VIR collection, advanced cultivars, hybrids and lines of various generations served as research material. The study was based on the guidelines for studying and maintenance of the collection and for cucurbit crop breeding.Results. Source material was identified for breeding practice: early accessions (90–98 days) possessing high productivity and fruit quality, with good taste, namely ‘Early Butternut’, ‘Butternut’, ‘Waltham Butternut’; accession k-3549, ‘Orekhovy’, and accession k-4235; and mid-early accessions (104–105 days) ‘Palov-kadu’, and ‘Aydzu Аkkikudza’. They exceeded in productivity the early-ripening reference (cv. ‘Mariya’) by 26.7–130%, and matched the reference in fruit quality. Hybrids from the crosses of vined accessions with the bushy form KL 745 were studied. Bushiness is inherited monogenetically and controlled by the recessive bu (bush) gene. Identified for breeding were early (93–95 days) bushy lines (KL) with a stem length of 0.8–1.2 m: KL 648, KL 652 and KL 656. Their productivity was within 4.2–4.5 kg per plant (higher than the reference by 40–50%). In fruit quality they were on the reference level. Early (92–98 days) short-vined lines (KPL) were identified, with a stem length of 1.3–2.0 m: KPL 168, KPL 640 and KPL 680; their productivity ranged 4.9–6.8 kg per plant, and their fruit quality was good or excellent

Genetic bases of compact forms among cucurbit crops

The genetic base of compactness has been an area of active research in recent years, with several genes and mutations identified to be associated with the appearance of dwarf phenotypes. Understanding the functions of these genes and the underlying mechanisms of dwarfism in cucurbit crops is essential for developing new cultivars with improved yield and fruit quality. This study presents current data on genes and mutations associated with the evolvement of compact phenotypes in cucurbit crops. The review includes examples of mutant compact phenotypes and their associated genes in representatives of the Cucurbitaceae family, such as Cucurbita maxima Duch., Cucurbita pepo L., Cucurbita moschata Duch., Citrullus lanatus (Thunb.) Matsum. &amp; Nakai, and Cucumis melo L. The review provides up-to-date information on the genetic and molecular bases of compact phenotype formation, as well as molecular markers for detecting known genes associated with reduced plant size