Mechanical segregation of apricot varieties and their ripeness levels at harvest

Some laboratory tests consisting on quasi-static compression and puncture forces carried out on twelve varieties of apricot during 1990 and 1991 were effective in sorting them. These mechanical properties show a high correlation w i th the ethylene production rate per fruit, so allowing to discriminate between ripeness levels at harvest. In this study it is also demonstrated that puncture seems to be the less variable mechanical test. The values (N/mm) obtained with it show a highly significant correlation with compression resistance and with quasi-static compression damage of the fruits.

Mechanical properties of peanut varieties

On the efforts for rationalizing the production of peanuts in Spain, one of the objectives was to obtain a well adapted variety, suitable for mechanization. We tried to get information on the characteristics that would condition the suitability of a variety to mechanized production, principally mechanical harvesting. All the characters studied would then be taken into account in a breeding program.

Relations between resistance of fruit and skin characteristics in tomato varieties.

Varietal differences in physical properties of processing tomato fruits related with resistance are determined. Mean values of skin resistance and firmness are highly correlated with rupture of the fruits by quasi-static compression and by impact. Skin resistance is dependent on the features of the epidermis, studied microscopically.

Fruit firmness and skin resistance of processing tomato varieties tested in Badajoz (Spain), related to mechanical harvesting.

Determinations of resistance to damage were carried out in a total of 31 tomato varieties for processing, with the purpose of choosing the most suitable ones for mechanical harvesting. The characteristics studied include: puncture, deformation and rupture of the fruits, the ease of detachment of the fruits also being determined. Seventeen varieties were chosen, for further tests, with values 0.76 to 1.7 2 N of resistance to puncture; 3 to 9 N/mm of resistance to compression and 2.16 to 29.40 N resistance to detachment.

Impact damage on selected varieties of apples, pears and other fruits.

During the past years, different laboratory impact response studies have been carrj.ec out in following fruits: apples (2 varieties), pears (4 varieties), Asian or Nashi pears (4 varieties), melons (2 varieties), peaches (2 varieties) and avocados. The methodology of the tests is described, as well as the results and observations obtained in each group of tests. Impact response is compared to bruising susceptibility, bruise characteristics (appearance and structural features) and varietal and ripeness differences.

Genetic characterization of chestnut (Castanea sativa Mill.) orchards and traditional nut varieties in El Bierzo, a glacial refuge and major cultivation site in Northwestern Spain

This paper presents a detailed genetic study of Castanea sativa in El Bierzo, a major nut production region with interesting features. It is located within a glacial refuge at one extreme of the distribution area (northwest Spain); it has a centenary tradition of chestnut management; and more importantly, it shows an unusual degree of genetic isolation. Seven nuclear microsatellite markers were selected to analyze the genetic variability and structure of 169 local trees grafted for nut production. We analyzed in the same manner 62 local nuts. The selected loci were highly discriminant for the genotypes studied, giving a combined probability of identity of 6.1 × 10−6. An unprecedented density of trees was sampled for this project over the entire region, and nuts were collected representing 18 cultivars marketed by local producers. Several instances of misclassification by local growers were detected. Fixation index estimates and analysis of molecular variance (AMOVA) data are supportive of an unexpectedly high level of genetic differentiation in El Bierzo, larger than that estimated in a previous study with broader geographical scope but based on limited local sampling (Pereira-Lorenzo et al., Tree Genet Genomes 6: 701–715, 2010a). Likewise, we have determined that clonality due to grafting had been previously overestimated. In line with these observations, no significant spatial structure was found using both a model-based Bayesian procedure and Mantel’s tests. Taken together, our results evidence the need for more fine-scale genetic studies if conservation strategies are to be efficiently improved.