Background: The timing of grape ripening initiation, length of maturation period, berry size and seed content are target traits in viticulture. The availability of early and late ripening varieties is desirable for staggering harvest along growing season, expanding production towards periods when the fruit gets a higher value in the market and ensuring an optimal plant adaptation to climatic and geographic conditions. Berry size determines grape productivity; seedlessness is especially demanded in the table grape market and is negatively correlated to fruit size. These traits result from complex developmental processes modified by genetic, physiological and environmental factors. In order to elucidate their genetic determinism we carried out a quantitative analysis in a 163 individuals-F 1 segregating progeny obtained by crossing two table grape cultivars.

A segregation population of 184 genotypes derived from a pseudo-testcross of table grapes (Vitis vinifera), together with 203 AFLP and 110 SSR markers was used to detect quantitative trait loci (QTLs) for fruit yield components. Diffferent QTLs, a low percentage of phenotypic variance explained by the QTLs detected and QTL instability over years were detected for each fruit yield component. These results confirm the complex genetic architecture of the yield components in grapevine due to the perennial nature of this species, which has to adapt to yearly variations in climate. Phenotypic correlation analyses between fruit yield components were also performed. The negative correlation between berry weight and the number of berries per cluster seems to have an indirect negative effect on cluster weight, as revealed by the path coefficient analysis; however, this negative correlation was not supported at the molecular level because no coincident QTLs were observed between these traits. Nonetheless, the possibility to select seedless genotypes with large berries without affecting cluster weight needs to be substantiated in future experiments because factors such as sample size and heritability might influence QTL identification in table grapes.

The leaf greenness (measured by a portable chlorophyll meter SPAD-501) has been used to differentiate table grape genotypes (Vitis vinifera) in water stress condition . The SPAD and chlorophyll values are lower in the stressed treatment after 2 weeks from the onset of stress . Linear response model has been observed between the chlorophyll content and the SPAD readings . The leaf greenness (SPAD readings) of apical and expanded leaves seems an easy indicator, which might be used for screening grape genotypes (Vitis vinifera) for drougth tolerance .

A large collection of melon (Cucumis melo L.) germplasm has been established at the Section of Genetics and Plant Breeding, Bari University (Italy). In the present work, data regarding the variation of 20 bio-agronomical traits recorded on entries and landraces collected in Albania and Apulia region (Southern Italy) are reported. The main objective of the study was to assess and describe, by means of univariate and multivariate analyses, the genetic diversity in the collection composed by genotypes classified in the Inodorus and Cantalupensis groups. The results obtained showed a large variation for all the traits examined. Furthermore, it was possible to identify valuable genotypes for future breeding programmes aimed at improving melon traits, particularly for the Inodorus group, which is an important crop in many Southern Italian sites. Genotypes of interest were especially selected for earliness and lateness, fruit shape, soluble solids content, storage time and fruit firmness.

Genotypic diversity has been detected among aromatic grapevines (Vitis vinifera) by molecular markers (AFLPs). The 22 primer-pairs generated a total of 1,331 bands of which 564 (40%) were polymorphic over all the genotypes. The bootstrap analysis pointed out that a large number of polymorphic bands (200-400) has to be used for a better estimation of the genetic distances among genotypes; 383 polymorphic AFLP bands were used for the cluster and the principal coordinate analyses because they did not present missing data across all the genotypes. The cluster analysis (UPGMA), based on polymorphic AFLP markers, revealed no relationship between the Moscato and Malvasia grapevines. The Malvasias, unlike the Moscatos distinguished by their distinct muscat aroma, have to be considered a more complex group because it includes muscat and non-muscat grapevines. The principal coordinate analysis (PCO) confirmed the pattern of the cluster analysis only for those varieties which presented a low coefficient of dissimilarity, while for the other varieties there was no correspondence between the two analyses. The pattern of aggregation among aromatic grapevines in the cluster and principal coordinate analyses does not support any classification that might include an aromatic grapevine group in V. vinifera. Even though some synonyms and homonyms are present among aromatic grapevines (V. vinifera), genetic diversity exists among genotypes in AFLP markers.