Calcium preharvest application influences fruit quality. The impact of preharvest foliar sprays using several commercial fertilizers with Ca content on the fruit quality and nutritional status of the kiwi cv. ‘Hayward’ was investigated for a 2-year period. Fruit flesh firmness increased under all Ca sprays compared to the control. Total soluble solids and acidity were not altered significantly by any of the studied Ca products. Treatment differences with regard to fruit firmness, soluble solids concentration and acids at harvest were maintained during cold storage for 2 and 4 months. Foliar sprays did not affect the N, P, K, Mg, B, Fe, Mn and Zn concentrations of leaves and fruits. However, all treatments increased the concentration of Ca in leaves and fruits compared to the control.

Fruits from wild forest trees and shrubs represent a natural source of antioxidants against oxidative stress and a growing market for novel minor crops. This study presents a multifaceted approach which sets the basis for sustainable agronomic exploitation of selected Greek native germplasm of four traditional but neglected and underutilized forest fruit trees and shrubs, namely Amelanchier ovalis Medik., Cornus mas L., Rosa canina L., and Sambucus nigra L. The studied plant species are traditionally used in Greek ethnobotany but are currently neglected and underutilized in commercial terms, thus characterized as neglected and underutilized plant species (NUPs). The investigation includes new information on the evaluation of the ex situ cultivation of the Greek germplasm (three of the four focal NUPs), thus supplementing respective full datasets for their comparative evaluation based on four evaluation axes (documentation and molecular authentication of genotypes, phytochemical evaluation, asexual propagation via rooting of cuttings, and ex situ cultivation) after multi-year and multifaceted groundwork data previously acquired. Consecutively, the work includes feasibility and readiness timescale evaluation for the sustainable exploitation of each focal species based on existing literature and extant research experience. The feasibility for sustainable exploitation and readiness timescale evaluation results were very encouraging, showing high exploitation feasibility with an already achieved readiness timescale for R. canina and S. nigra, whereas C. mas and A. ovalis showed an achievable readiness in the short term. The comparative evaluation of the Greek native focal NUPs outlined the excellent potential of R. canina, S. nigra, and A. ovalis, and the high potential of C. mas. The results herein illustrate the very high fruit antioxidant potential (free radical scavenging activity) of all focal species, the diverse but effective asexual propagation capacity via cuttings at the species level, and summarize the results of a pilot cultivation trial set up in 2020 (still ongoing) outlining tree growth rates and the onset of fruit production among genotypes and species. Overall, the meta-analysis of previously published data in conjunction with new data generated herein may serve the sustainable exploitation of the studied NUPs.

Wild-growing Cornelian cherries (Cornus mas L., Cornaceae) are well-known native fruits in Greece since ancient times that are still consumed locally nowadays. Modern research has highlighted the value of Cornelian cherries as functional food with exceptional health benefits on account of the fruits’ biochemical profile. However, apart from local consumption directly from wild growing individuals, Greek native C. mas populations have not yet been investigated or sustainably utilized. A multifaceted evaluation was conducted herein including authorized collection-documentation, taxonomic identification, and molecular authentication (DNA barcoding), asexual propagation via cuttings and phytochemical evaluation (multiple antioxidant profiling) of neglected and underutilized Greek native C. mas germplasm sources. Successive botanical expeditions resulted in the collection of 18 samples of genotypes from distant C. mas populations across different natural habitats in Greece, most of which were DNA fingerprinted for the first time. Asexual propagation trials revealed high variability in rooting frequencies among Greek genotypes with low (50%) using external indole-3-butyric acid (IBA) hormone application on soft- or hard-wood cuttings. The comparative phytochemical evaluation of the studied Greek genotypes showed significant potential in terms of antioxidant activity (>80% radical scavenging activity in 13 genotypes), but with variable phenolic content (47.58–355.46 mg GAE/100 g), flavonoid content (0.15–0.86 mg CE/100 g), and vitamin C content (1–59 mg AAE/100 g). The collected material is currently maintained under ex situ conservation for long-term monitoring coupled with ongoing pilot cultivation trials. The pivotal data create for the first time a framework for the sustainable utilization of Greek native C. mas germplasm as a superfood with significant agronomic potential.

Ιn an effort to create walnut cultivars (Juglans regia) with high productivity, fruit quality and lateral bearing, a new cultivar, named “Leto”, was created by the cross “Gustine” × “Pedro”. Its main phenological and pomological characteristics were assessed according to the criteria of IPGR (1994) and UPOV-TG/125/6 (1999), for 10 consecutive years and compared with its maternal cultivars and “Chandler”. Observations showed that “Leto” has high lateral bearing habit (90%) and presents satisfactory yield at the full production age. The tree size is smaller than that of its parents and “Chandler”, female flowers bloom from 11 to 22 of April and male from 3 to 6 of April. “Leto” nuts are harvested at the end of September, present easy hull dehiscence and high kernel percentage. Other positive nut characteristics of “Leto” are light kernel color, well kernel filling and easy removal of the kernel halves. “Leto” is a mid-early cultivar of great interest due to its high- quality nuts, suitable for dense plantings, in regions where the last spring frosts occur in late March to early April, thus, making it a promising cultivar for Greece, but also for other regions with similar geomorphological and climatic conditions.

Walnut (Juglans regia L.) is a monoecious species and although it exhibits self-compatibility, it presents incomplete overlap of pollen shed and female receptivity. Thus, cross-pollination is prerequisite for optimal fruit production. Cross-pollination can occur naturally by wind, insects, artificially, or by hand. Pollen has been recognized as one possible pathway for Xanthomonas arboricola pv. juglandis infection, a pathogenic bacterium responsible for walnut blight disease. Other than the well-known cultural and chemical control practices, artificial pollination technologies with the use of drones could be a successful tool for walnut blight disease management in orchards. Drones may carry pollen and release it over crops or mimic the actions of bees and other pollinators. Although this new pollination technology could be regarded as a promising tool, pollen germination and knowledge of pollen as a potential pathway for the dissemination of bacterial diseases remain crucial information for the development and production of aerial pollinator robots for walnut trees. Thus, our purpose was to describe a pollination model with fundamental components, including the identification of the “core” pollen microbiota, the use of drones for artificial pollination as a successful tool for managing walnut blight disease, specifying an appropriate flower pollination algorithm, design of an autonomous precision pollination robot, and minimizing the average errors of flower pollination algorithm parameters through machine learning and meta-heuristic algorithms.

"‘Ourania’ Walnut" published on 26 Feb 2021 by American Society for Horticultural Science.