Table grapes are a crop with high nutritional value that need to be monitored often to achieve high yield and quality. Non-destructive methods, such as satellite and proximal sensing, are widely used to estimate crop yield and quality characteristics, and spectral vegetation indices (SVIs) are commonly used to present site specific information. The aim of this study was the assessment of SVIs derived from satellite and proximal sensing at different growth stages of table grapes from veraison to harvest. The study took place in a commercial table grape vineyard (Vitis vinifera cv. Thompson Seedless) during three successive cultivation years (2015–2017). The Normalized Difference Vegetation Index (NDVI) and Green Normalized Difference Vegetation Index (GNDVI) were calculated by employing satellite imagery (Landsat 8) and proximal sensing (Crop Circle ACS 470) to assess the yield and quality characteristics of table grapes. The SVIs exhibited different degrees of correlations with different measurement dates and sensing methods. Satellite-based GNDVI at harvest presented higher correlations with crop quality characteristics (r = 0.522 for berry diameter, r = 0.537 for pH, r = 0.629 for berry deformation) compared with NDVI. Proximal-based GNDVI at the middle of veraison presented higher correlations compared with NDVI (r = −0.682 for berry diameter, r = −0.565 for berry deformation). Proximal sensing proved to be more accurate in terms of table grape yield and quality characteristics compared to satellite sensing.

Hailstorms are typically localized events, and very little is known about their effect on crops. The objective of this study was to examine the physiological and vine performance responses to natural hail, registered four weeks after full bloom, of field-grown Thompson seedless (Vitis vinifera L.) grapevines, one of the most important table grape varieties cultivated in Greece and especially in the Corinthian region in northeastern Peloponnese. Leaf gas exchange, vegetative growth, vine balance indices, cane wood reserves, yield components, and fruit chemical composition were recorded from hail-damaged vines and compared with control vines. Visibly, the extent of the hailstorm damage was great enough to injure or remove leaves as well as cause partial stem bruising and partial injury or total cracking of berries. Our results indicated that natural hail did not affect leaf photosynthesis, berry weight, total acidity, and cane wood reserves but significantly reduced the total leaf area, yield, and the total phenolics of berries at harvest. At the same time, hail-damaged vines increased the leaf area of lateral canes and presented a higher total soluble solid (TSS) accumulation, while no effect on the next year’s fertility was registered. The present work is the first attempt to enhance our understanding of the vegetative yield, berry quality, and physiological responses of grapevines to natural hail, which is an extreme and complex natural phenomenon that is likely to increase due to climate change.

The aim of this study was the identification and discrimination of 49 grapevine varieties that are cultivated in northern, western and central Greece with the use of the ampelographic description and the molecular method RAPD. The grapevine varieties were located in their cultivation centers and the studied samples were collected from productive vineyards of these regions. For the ampelographic description, 22 ampelographic characters were used following a list of descriptors developed by the International Organization of Vine and Wine (OIV), while for the molecular analysis 8 of the most polymorphic primers were used. The results showed that: (a) there is high degree of genetic heterogeneity among most of the varieties studied, (b) grapevine varieties ‘Xinomavro’ and ‘Zalovitiko’ exhibited identity with both methods used, therefore the latter constitutes a synonym/clone of the former, (c) high degree of genetic similarity was recorded between cv ‘Stavroto’ and ‘Abelakiotiko’, a result enhancing the view that they constitute biotypes/clones of an original/parent variety and originated through the accumulation of mutations, (d) a previous hypothesis is confirmed. This hypothesis states that in the vineyards of northern Greece, different varieties of Vitis vinifera L. as well as hybrids (direct producers) were imported. Names/synonyms were given to these imported varieties and hybrids related to their place of origin or the morphological traits of the grape/berries implying identity among them (‘Mavroudi’, ‘Voulgariko’, ‘Voulgaroudia’, ‘Vapsa’ etc.), while they are different varieties, (e) the combination of the ampelographic description and the molecular method RAPD is very effective in the identification and discrimination of grapevine cultivars.