The main purpose of this study is to determine the contents of 3 major phenolic compounds (gallic acid, catechin, and epicatechin) in 22 different grape cultivars/hybrids obtained from 2 different breeding programs. Additionally, changes in these phenolic components in the grape leaves of some resistant/tolerant species were determined in relation to powdery and downy mildew diseases in viticulture. The skin, pulp, and seeds of grape berries were analysed over two years, while changes in the phenolic contents of grape leaves were determined before and after these diseases for two years. The major phenolic contents of new hybrids/cultivars were compared with those of popular cultivars in different parts of the grapes, and significant differences in phenolic contents were found among hybrids/cultivars and different grape parts. Variations in the contents of phenolics in grape seeds, skins, and pulp were high, but seeds contained higher levels of these phenolics than pulp and skin. Analyses of the relationship between two viticultural diseases and phenolic changes in resistant/tolerant cultivars in relation with the susceptible “Italia” cultivar revealed that an increase in the content of the phenolic compounds was found after powdery mildew disease. Hybrids/cultivars with high phenolic contents are recommended to develop new superior cultivars, which are resistant to grape fungal diseases, in breeding programs.

Many wild plant species are actually true treasures of our world. The value of these treasures is better understood today and many wild species are used for different purposes. Also Vitis species are among the most important species with their ancient history. China and North America are the native ranges of many Vitis species that survive to the present day, most of which have survived by natural selection. These species have attracted the attention of plant breeders for many years due to their resistance to various biotic and abiotic stress conditions, and they have used these species to develop new cultivars. In parallel with the developments in the field of biotechnology, interspecific hybrid genotypes obtained in breeding research for resistance to different stress conditions can be obtained in accordance with the targets in a much shorter time. In these investigations, gene regions in Vitis species with resistance genes were transferred to new hybrid genotypes. Additionally, these species have been used as parents in many breeding programs in different countries due to their resistance to biotic stress conditions, especially fungal diseases. Similar breeding research has been carried out on tolerance to abiotic stress conditions, and interspecific cross-breeding have been made to develop hybrid genotypes that are more tolerant to many abiotic stress conditions. In recent years, resistance and high-quality wine and table grape cultivars obtained from rossbreeding have begun to be used in production. As a result, newly developed interspecific hybrid grapes can be grown with much lower production costs in accordance with the sustainable viticulture model.

Many grape varieties or genotypes of Vitis species are grown for different purposes in various parts of the world. However, despite a large number of cultivars, there is a demand for different grape cultivars due to changing consumer expectations. Grapevine breeding programs are carried out by scientists in different countries in order to meet these expectations. Breeding studies, which used to take a long time with traditional crossbreeding methods, have become studies that achieve the desired results in a much shorter time with the development of molecular methods and biotechnology. One of the most important developments in grapevine breeding is that the relevant gene regions in hybrid populations developed from breeding programs can be identified in a very short time. In recent years, the demand for cultivars that are more resistant or tolerant to biotic and abiotic stress conditions has increased, and for this purpose, there has been a significant increase in breeding studies on cultivars and rootstocks that are resistant or tolerant to different stress conditions. Considering the current breeding programs, genetically manipulated new cultivars with desired characteristics and interspecies hybrid cultivars will soon become the main study subjects of grapevine breeding programs.

The presence of dormant embryos in seeds and nonuniformity in seedling growth are the main limiting factors for kiwifruit propagation. Studies on the germination of hybrid genotypes are limited, especially at different ploidy levels. Low germination percentages and nonuniformity in seedling growth are two of the limiting factors of kiwifruit breeding, especially new and imported germplasm. The effect of cold moist stratification and growing substances on seed germination and seedling growth, respectively, on different kiwifruit seed populations were evaluated in this study. The effect of cold moist stratification (3, 4 and 5 weeks at 4 °C) and growing substrate composition (peat, perlite and coco peat) on seed germination and seedling growth of different Actinidia genotypes were assessed. In general, increasing stratification period duration often increased germination speed and uniformity. It was also found that increasing the ratio of peat moss improved the vegetative growth parameters of all kiwifruit seedlings. Stratification treatment, light and temperature fluctuation and consequently suitable substrate can accelerate and increase the production of seedlings and reduce seedling losses. It was also found that peat–perlite (1:1) medium was the best medium for kiwifruit seedling growth.