Almond Fruit Drop Patterns under Mediterranean Conditions

Almond is an important tree nut crop worldwide, and planted areas have been increasing year after year. While self-fertility is one of the key factors when it comes to improved almond productivity of new cultivars, yield is also affected by the number of flowers produced, pollination, fruit set, fruit drop, and fruit weight. Almond fruit drop patterns of 20 Mediterranean almond cultivars were studied over three years. In addition, fruit drop patterns of two scion cultivars ‘Marinada’ and ‘Vairo’ budded onto eight to 10 different rootstocks managed with three different pruning strategies were studied for two years. Cumulative flower and fruit drop ranged from 50% to 90% among cultivars and treatments, and there were up to four fruit drop events during the growing season, the main one occurring from 20–60 days from full bloom (DFFB). Subsequent drops were at 100 DFFB, 120–140 DFFB, and the last one at 160–180 DFFB. The later drops were less apparent. In general, about half of the cumulative drop was comprised of buds and flowers, and the remaining percentage was fruit that dropped 20 or more days after full bloom. Furthermore, different fruit drop patterns were observed depending on the cultivar. For late- and extra-late flowering cultivars, cumulative fruit drop began to decrease earlier, with most of the drops occurred already at full bloom, whereas the opposite was observed for the early flowering cultivars. Rootstocks also had an important effect on the fruit drop pattern, with different effects depending on the scion cultivar. Tree management, such as type of pruning, also had an important effect on the rate of fruit drop and cumulative drop. Therefore, each combination of cultivar × rootstock × pruning type will require different strategies in order to reduce the fruit drop and optimize crop loads.

Vegetative growth of apricot (P. armeniaca L.) cultivars and rootstocks

The continuous innovation in point of apricot cultivars and rootstocks requires comparative trials, which can be evaluated by precise measurements. An experiment is established, initiated from the recent trends. 15 scion cultivars were budded on 6 different rootstock cultivars. Apricot seedling, Montclar, Myrobalan 29C, Wavit, Rootpack R and Fehér besztercei were used as rootstock. Scions included traditional Hungarian cultivars (Gönci Magyar kajszi, Ceglédi óriás, Ceglédi szilárd, Pannónia), naturalized cultivars (Bergeron, Roxana) and modern cultivars too (Goldrich, Tardif de Valence, LadyCot, FlavorCot, PinkCot, Spring Blush). The experiment was settled at spring of 2018, with 3⇥5 m spacing. Sprouting was 98%, the deficiency was originated only from fawn damage. The main effect of the different rootstocks can be observed in the growth habit of scions, meanwhile the scion cultivar also has a moderate impact.

Initial development of peach rootstock genotypes propagated by herbaceous cuttings

The peach tree is a temperate fruit tree propagated by grafting with the scion cultivar and the rootstock from seeds, generating low uniformity, a viable alternative is propagation by herbaceous cuttings. The objective of this study was to evaluate the performance of different genotypes of peach rootstock propagated by herbaceous cuttings. The experiment was carried out with standardized cuttings of 15 cm in length treated with 3,000 mg L-1 of IBA solution, then were transplanted into 3 L polyethylene bags. A completely randomized design with five replications was adopted, each plot consisting of three plants. Sixteen peach genotypes from UFV breeding program were tested: 713-3, 713-6, 713-7, 713-10, 813-2, 813-3, 813-5, 813-15, 913-3, 913-6, 913-11, 913-17, C6, C7 and C8. After 80 days the following parameters were evaluated: stem length (cm), stem diameter (mm) and internode length (cm). Data were subjected to analysis of variance by the F test and averages compared by the Scott-Knott test at a 5% probability level with the GENES statistical software. It can be concluded that the lower initial development was observed in genotype 1113-11 and the highest initial development was from genotypes 713-13 and 813-5.

Use of root pruning, paclobutrazol, and prohexadione-Ca combination strategies to control growth and improve productivity on pear trees

Growth control in pear orchards is essential, not just to reduce competition between vegetative and reproductive sinks, but also to improve return bloom, yield and fruit quality. The goal to optimize growth control, return bloom and yield must be pursued with the integration or combination of several strategies. Aim of this study was to assess the use of root pruning, paclobutrazol, and prohexadione-Ca (ProCa) either alone or in combination, to control growth and improve productivity on pear trees. The experiment was conducted during three years in a 10 year-old pear orchard with ‘Blanquilla’ as the scion cultivar. All of the different strategies that were assessed improved growth control in pear trees, with different grade depending on the strategy. Control trees had about 50% of the shoots shorter than 60 cm, root pruning 63%, ProCa 70%, paclobutrazol and root pruning plus ProCa 83%, and root pruning plus paclobutrazol 86%. In addition, yield, fruit weight and return bloom were more affected by applications of ProCa than paclobutrazol. Use of paclobutrazol either alone or in combination with root pruning seems to be most suitable for situations of high-vigor cultivars. The fact that use of paclobutrazol may be challenged again in the future, leave combinations of root pruning plus ProCa as the best shot for vigorous cultivars. In other situations of medium-low vigor, ProCa alone would be the best strategy.

THE PHENOLOGICAL AND POMOLOGICAL TRAITS OF SELECTED GENOTYPES OF WILD PEAR [Pyrus pyraster (L.) Du Roi] IMPORTANT FOR THE PRODUCTION OF GENERATIVE ROOTSTOCKS

The aim of this work is to produce the generative rootstocks for the wild pears, which will be of moderate denseness. The initial material is the population of wild pear in the area of Polimlje. The study focused on few segments. Very first one included recording of the phenological traits – first flowering, full flowering, end of flowering and harvest period. The other segment comprised pomological features, i.e. physical [fruit weight (g), fruit size (mm), mass of dry seed (g), and number of seed in 1 kg of the fruit]. Seeds from 9 selected genotypes of wild pears were planted in the nursery and raised seedlings were evaluated for nursery characteristics: germination, seedling vigor, uniformidty and branching. Raised seedlings were used as rootstocks for scion cultivar ‘Grand Champion’. The most important benefit of this study is the fact that the parent trees, the seeds of which provide the best morphological and physiological characteristics for the production of generative rootstocks, were found and favored (in situ). Results of this research show that the rapid growth and uniformity of scions depend on the genetic characteristics of generative rootstocks of selected genotypes of wild pears, such as: plant height, stem diameter (corpulence), branching and uniformity. The selected genotypes, especially ‘Genotype 11’, proved to be the best for mountainous areas of the north of Montenegro, higher altitudes and poorer types of soil. The ‘Genotype 11’ is suggested as the best option for the production of generative rootstocks due to its small vigour level.

ADVANCES IN PEACH, NECTARINE AND PLUM PROPAGATION

ABSTRACT Nursery trees of stone fruits (Prunus spp.) are traditionally produced by union of two distinct genotypes - the rootstock and the scion - which, by grafting, form a composite plant that will be maintained throughout of all plant life. In Brazil, the rootstocks are predominantly seed propagated and therefore usually results in heterogeneous trees for vigor and edaphic adaptation. However, with advances in rootstock breeding programs that released cultivars and certification in several countries (notably in Europe), the system will come gradually evolving for vegetative propagation (cuttings and tissue culture) and use of seeds of selected rootstocks with specific characteristics and potted nursery trees production. For scion cultivar propagation, the budding system (with its many variations) has predominantly been adopted in major producing countries. This review had as objective to comment main propagation methods adopted for rootstocks and scion in peach, nectarine and plum, and recent technical progress obtained as well as the needs of improvement for nursery tree production.