Pollen tube behavior in different Mandarin hybrids

Seedlessness is an important trait in the evaluation of commercial mandarin for fresh consumption. However, in the last decade, the presence of seeds in fruit of cultivars considered as seedless has become a problem in different citrus-growing areas because the commercial value is depreciated. Seeds have appeared concomitantly with the introduction of new cultivars that appear to be cross-compatible. To overcome this problem, different strategies have been explored, but a definitive answer is still elusive. The search for alternatives contrasts with how little is known about the basis of the problem: the pollen-pistil incompatibility reaction in mandarin, and the intercompatibility relationship between different cultivars. In this work, we characterized the pollen-pistil incompatibility in the two commonly grown mandarin cultivars Fortune and Nova, and evaluated the intercompatibility relationship between six cultivars with different genetic origins; these cultivars included Fortune (Citrus clementina Hort. ex Tan. × Citrus reticulata Blanco), Nova [(Citrus paradisi Macf. × C. reticulata) × C. clementina), Comune Clementine (C. clementina), Avana apireno (C. reticulata), Primosole (Citrus unshiu Marcov. × C. reticulata), and Simeto (C. unshiu × Citrus deliciosa Ten.). Following the controlled hand pollination in the field, we evaluated pollen tube performance after self- and cross-pollination, as well as intercultivar compatibility by observing pollen tube growth. The results show the self-incompatibility of these cultivars with the pollen tube having been arrested in the style, which explains their seedless condition when planted in solid blocks. The study of intercompatibility indicates a different pollen tube behavior depending on the genotype, as well as on the cross combinations. These results provide a basis to evaluate self- and intercompatibility in citrus, and the effect of close planting of some cultivars.Financial support for this research was provided by the Italian Ministry of Agriculture and Forestry, Project RAVAGRU (Advanced research in citriculture), publication no. 32; by the Italian Ministry of the University, Project PRIN ‘‘The productive process in fruit tree species: molecular, physiological, and agronomical aspects of floral incompatibility and strategies for its control’’; by the Minister of Science and Innovation, EU Feder (Project grant CICYT AGL-2006-13529-CO2-01/AGR); and by the Grupo de Excelencia del Gobierno de Aragón A-43.Peer Reviewe

Influence of film wrapping and fludioxonil application on quality of pomegranate fruit

Pomegranates are sensitive to low temperatures. When fruit are exposed to temperatures below 5–6 °C chilling injury appears as pitting of the skin, browning of the white segments separating the arils and discoloration of the arils, and husk scald, which generally is more severe at temperatures of 6–10 °C. The main objective of this work was to assess the effectiveness of individual film packaging, applied as a stand alone treatment or in combination with fludioxonil, on reducing the occurrence of husk scald, weight loss and decay. Fruit were dipped in an aqueous mixture containing 600 mg L−1 fludioxonil, wrapped or not wrapped with a polyolephinic heat-shrinkable film and stored at 8 °C and 90% RH for 6 or 12 weeks plus one additional week of simulated shelf-life at 20 °C and 65–70% RH. Respiration rate decreased both in cold storage and at 20 °C. Ethylene production was not detected during cold storage; its rate increased upon transfer to 20 °C, but results were inconsistent. Control fruit deteriorated at a very high rate, due to excessive weight loss, skin browning and decay. Film wrapping almost completely inhibited weight loss and husk scald and preserved fruit freshness for the whole storage time. There was no statistical difference in decay incidence between wrapped and control fruit after 6 or 12 weeks of storage and after the first shelf-life, while after the second shelf-life, wrapped fruit had significantly higher decay levels. By contrast, fludioxonil, both alone and in combination with wrapping, effectively controlled mold development, resulting in 50–67% less decay than control fruit after 12 weeks at 8 °C plus one week shelf-life. Control fruit showed minor changes in nutritional compounds as well as in total polyphenols, anthocyanins and antioxidant activity, while higher losses were detected in film-wrapped fruit during storage at 20 °C