Quantification of dwarfing effect of different rootstocks in ‘Picual’ olive cultivar using UAV-photogrammetry

Hedgerow orchard is an olive growing system where trees are planted at a super high-density higher than 20-fold (i.e., 1200–2500 trees ha−1) compared to the traditional density of olive orchards (usually 50 to 160 trees ha−1). It is dominating a great proportion of new plantations because harvesting can be fully mechanized, it is early bearing and has a relatively constant high productivity. However, there are a limited number of cultivars with sufficiently low vigour to be suitable for such plantation densities. For that reason, a set of low vigour cultivars and breeding selections has been used in a field experiment as rootstocks for reducing the vigour of “Picual”, the most frequent cultivar planted in Spain. Tree vigour was characterized by measuring crown height, projected and side areas, and volume through the analysis of photogrammetric point clouds created from images acquired with an unmanned aerial vehicle. A significant reduction of the ‘Picual’ vigour was observed in most of the rootstocks tested, with canopy volume reduced up to one half. High variability on vigour, first harvesting and their relative relationship was observed between the different rootstocks used. This indicates there might be enough genetic variability to perform breeding selection for dwarfing rootstocks on ‘Picual’ olive cultivar.

ISPITIVANJE SORTI ŠLJIVE RANOG VREMENA SAZREVANJA PLODA NA PODRUČJU ČAČKA

Although there are more than 6000 plum varieties originated from different wild species from Europe, Asia and North America, there is a constant need to develop new varieties with better characteristics, tolerant/resistant to adverse environmental factors and the most important diseases, in the first place Sharka virus. In addition, one of the most important aims of plum breeding in the world is to create varieties of early and late ripening time in order to prolong the season of fresh fruits on the market as much as possible. The aim of this study was to examine the most significant pomological and productive characteristics of two domestic (ʻBorankaʼ and ʻC ačanska ranaʼ) and three introduced (ʻOpalʼ, ʻKatinkaʼ and ʻTegeraʼ) early ripening plum varieties. The most important phenological (phenophase of flowering and fruit ripening) and morphometric characteristics (fruit and stone mass, flesh percentage ratio, fruit dimensions and sphericity), as well as tree vigour (trunk cross-sectional area) and yield (yield per tree and yield efficiency) were examined.

Breeding and spread of the apple (Malus domestica Borkh.) new cultivars

The main task of the apple present day breeding is creation of intensive cultivars. In order to accelerate this process at present is the knowledge which has been accumulated in the genetics of the traits of the necessary crop. It is much simpler to carry out breeding on the traits that are controlled by the major genes. If any trait is conditioned by the dominant allele of the major gene it is possible to expect half of seedlings with this trait in the offspring as a result of the crossing. Such approach enables to plan and valuate objectively a great number of seedlings at the primary stages. The principle of a new сv creation is almost similar both in Ukraine and abroad. But in other countries this process is more modern since new laboratories are at the service of a breeder which can accelerate the appearance of a new variety by some years. That′s why this cultivar is more expensive. However that does not guarantee the creation of “ideal” cultivar which would meet all the requirements of a producer and consumer and in most cases such сv becomes known and spreaded not thanks to its certain unrepeatable signs but due to publicity. The breeding on the obtaining of a new apple variety is long-term labour-consuming and complicated work including many stages – from the hybridization to entering into the State Register of the Plant Cultivars Favourable for the Spread in Ukraine. The presence of the registration and licence for the further reproduction as of сv for the wide manufacturing introduction is a very suitable factor but it does not suffice the promotion at the market. Certainly, as in case of everything new many doubts, misgivings and questions appear in this connection and in order that a demand emerge on a new variety and it become known, beside publicity, it is necessary to show all the advantages and potential as compared to the spreaded cultivars and present complete recommendations concerning the peculiarities of its growing, the substantial robe belonging to a rootstock which influences the tree vigour and fruit early ripening and quality. Therefore the testing оn some most spreaded or new rootstocks should be conducted under different planting plans including the trees pruning, ovary thinning, measuments on the soil management and fertilizing and leaf-feeding dressing into the plants management system in order to ensure the high annual crop.

Pomological and phenological characteristics of the main pistachio cultivars in Greece

The present study aimed to evaluate the pomological and phenological traits, as well as kernel antioxidant potential of the dominant Greek pistachio cultivars, ‘Aegina’ and ‘Pontikis’ (Pistacia vera L.). Blooming of ‘Aegina’ cultivar occurred from early to mid of April, and nut maturation at middle to late of August. Production started at 6 to 7 years from grafting and full production observed at year 13. Blooming and nut maturation of ‘Pontikis’ occurred about 1 to 2 days later than ‘Aegina’ and production started 6 to 7 years from grafting, with full production observed in the 14th year. Mean tree yields reached 18.0 ± 1.0 kg and 17.4 ± 1.1 kg of dry nuts, in ‘Aegina’ and ‘Pontikis’ cultivar, respectively. ‘Aegina’ cultivar presented intermediate tree vigour and spreading growth habit, whereas ‘Pontikis’ high tree vigour and semi-erect growth habit. ‘Aegina’ nut had a narrowly cordate shape and the percentage of split nut was found at 78.5 ± 6.5. ‘Pontikis’ nut had ovoid shape and the percentage of split nut was 84.1 ± 6.2. In ‘Aegina’ cultivar 100 nuts weighted 101.0 g and in ‘Pontikis’ 114.4 g. Color of kernel was green externally and green to green-white internally, greener in ‘Pontikis’. The antioxidant potential of pistachio kernel measured by FRAP assay, total polyphenolic substances, flavonoids, flavanols and hydroxycinnamic acids content, did not differ (P > 0.05) between cultivars. Evaluation of ‘Aegina’ and ‘Pontikis’ pistachio cultivars revealed that both are high yielding, with large nut sizes of acceptable appearance and high quality.

Correlations of Soil Fungi, Soil Structure and Tree Vigour on an Apple Orchard with Replant Soil

The soil-borne apple replant disease (ARD) is caused by biotic agents and affected by abiotic properties. There is evidence for the interrelation of the soil fungal population and soil aggregate structure. The aim of this study conducted between March and October 2020 on an orchard in north-east Germany was to detect the correlations of soil fungal density, soil structure and tree vigour under replant conditions in a series of time intervals. By using the replant system as the subject matter of investigation, we found that replanting had an impact on the increase of soil fungal DNA, which correlated with a mass decrease of large macro-aggregates and an increase of small macro- and large micro-aggregates in the late summer. Increased proportions of water-stable aggregates (WS) with binding forces ≤ 50 J mL−1, decreased proportions of WS > 100 J mL−1 and a decrease of the mean weight diameter of aggregates (MWD) emphasised a reduction of aggregate stability in replant soils. Correlation analyses highlighted interactions between replant-sensitive soil fungi (Alternaria-group), the loss of soil structure and suppressed tree vigour, which become obvious only at specific time intervals.

Relevance of stem and crown defects to estimate tree vigour in northern hardwood forests

The visual assessment of tree vigour before partial cutting is a key element of the long-term sustainability of managed hardwood forests. Several classification systems have been developed and applied to perform this task during the tree marking process. They segregate trees in different vigour classes based on the presence and severity of stem and crown defects. Yet, the relevance of using these defects to assess tree vigour has rarely been empirically validated. In this study, we analysed the relationships between quantitative vigour indicators and a full range of individual defects using 336 sugar maple and 84 yellow birch trees. Among the tested defects, the tree crown density showed the best ability to identify slow growing, non-vigorous sugar maple trees, regardless of their size. However, none of the stem-related defects, such as bark aspect, the presence of cambial necrosis or conks and stromata were strongly related to our quantitative vigour indicators. For yellow birch, none of the stem defects and crown conditions were found to be related to our vigour indicators. We conclude that, pending longitudinal studies that will provide a full empirical validation of classification systems, crown density should be used to assess recent growth and vigour of sugar maple trees and guide tree marking.