Evaluation of Phenological and Agronomical Traits of Different Almond Grafting Combinations under Testing in Central Italy

In the new introducing almond areas, it is necessary to test the more promising almond cultivar and rootstock combinations able to guarantee the best agronomic performances according to the specific pedoclimatic conditions. With this aim, two almond trials have been established in an experimental farm located in the Latium region (Italy). The first trial (A) focused on the phenological, and agronomical influences induced by the clonal rootstock ‘GF677’ on the grafted cultivars ‘Tuono’, ‘Supernova’ and ‘Genco’, in comparison to those induced by peach seedling rootstocks, in order to identify the best grafting combination for developing “high density” plantings in this new growing area. The second trial (B) tested the phenological and agronomical influences induced by three different clonal rootstocks (‘GF677’, ‘Rootpac® 20’ and ‘Rootpac® R’), on the Spanish cultivar ‘Guara’ to identify suitable dwarfing rootstocks for “super high density” plantings in the same environment. Flowering and ripening calendars of the trial A highlighted as the medium-late flowering cultivars ‘Genco’, ‘Supernova’ and ‘Tuono’ could be subject to moderate risk of cold damages. The clonal rootstock ‘GF677’ seems to anticipate flowering and vegetative bud break by a few days in ‘Tuono’ when compared to the same cultivar grafted on peach seedling rootstocks. Furthermore, the yield per plant was always higher in plants grafted on ‘GF677’. The observations carried out in trial B highlighted as the flowering of cultivar ‘Guara’ were affected by the rootstock, with ‘Rootpac® 20’, which postponed its full bloom of about one week when compared to other rootstocks, whereas ‘GF677’ imposed more vigor to the cultivar than ‘Rootpac® 20’ and ‘Rootpac® R’.

Bud endodormancy in deciduous fruit trees: advances and prospects

Bud endodormancy is a complex physiological process that is indispensable for the survival, growth, and development of deciduous perennial plants. The timely release of endodormancy is essential for flowering and fruit production of deciduous fruit trees. A better understanding of the mechanism of endodormancy will be of great help in the artificial regulation of endodormancy to cope with climate change and in creating new cultivars with different chilling requirements. Studies in poplar have clarified the mechanism of vegetative bud endodormancy, but the endodormancy of floral buds in fruit trees needs further study. In this review, we focus on the molecular regulation of endodormancy induction, maintenance and release in floral buds of deciduous fruit trees. We also describe recent advances in quantitative trait loci analysis of chilling requirements in fruit trees. We discuss phytohormones, epigenetic regulation, and the detailed molecular network controlling endodormancy, centered on SHORT VEGETATIVE PHASE (SVP) and Dormancy-associated MADS-box (DAM) genes during endodormancy maintenance and release. Combining previous studies and our observations, we propose a regulatory model for bud endodormancy and offer some perspectives for the future.

Rootstocks.

Plants of many horticultural crops consist of multiple genetic systems, two or more distinct genotypes joined together as a single plant. The components are identified as the rootstock, interstem and scion. Grafting and budding are the processes that combine these components to establish vascular continuity between them to produce a single plant. Grafting may be natural or human initiated, forced grafting. This datasheet will mainly consider forced grafting with only a brief discussion of natural grafting. The rootstock is that component of the plant that fuses with the scion and provides the plants root system. Other terms used to describe this lower portion of the plant include stock and understock. Stock is synonymous with both rootstock and understock. Understock implies that the lower portion of the plant provides both the root system and some of the trunk while rootstock or stock implies that only the root system is provided by the lower piece. When grafting is performed high on the rootstock, the rootstock may also provide scaffold limbs. The scion is the plants shoot system. It is the component that produces the desired commodity in most cases, which are usually flowers or fruit. In perennials, the scion is nearly always vegetatively propagated. In grafted vegetables, the scion is usually propagated via seed. An interstem is a third genetic component of some grafted plants and is often selected to provide compatibility between the rootstock and the scion. Both grafting and budding combine dissimilar genotypes into one plant. Budding is a form of grafting where a single vegetative bud is used as the scion or interstem. Grafting refers to the condition where more than one bud on a common stem piece are combined with the rootstock or interstem. Perennial ornamental and fruit crops are the grafted crops that are familiar to most horticulturists. Annual vegetable crops are increasingly being grown as grafted plants and interest in using them in commercial production is rising steeply. Short lists of common rootstocks for a number of ornamental, fruit, nut and vegetable crops are presented in Tables 1-3 (at the bottom of this article). These lists are by no means complete, but provide an insight into the large number of rootstocks available in modern horticultural production. Specific recommendations for an area should be obtained from local experts. Good rootstocks should possess as many of the following crop appropriate characteristics as possible: affordable, long term graft compatible, easily propagated, promotes precocity and productivity, controls scion vigour, conveys pest resistance, improves stress tolerance, and has minimal suckering.

Morphology and symmetry of the vegetative parts of Smilax auriculata (Smilacaceae)

Smilax auriculata produces a subterranean rhizome system and an aerial vegetative branching system. Three intergrading types of stems (types 1, 2, and 3) compose the aerial branching system; these types are identified primarily according to prickle concentration, but also differ from one another in additional ways. Type-3 stems are determinate and either proleptic or precocious. Between growing seasons a foliage leaf of a type-3 stem may subtend either a solitary vegetative bud (or an expanded vegetative branch) or an inflorescence superposed over a vegetative bud (or expanded vegetative branch). Occasionally, an inflorescence terminates a type-3 stem. Whereas, rhizomes exhibit solely scale leaves, the aerial vegetative branching system manifests scale leaves, transitional leaves, and foliage leaves. On many type-3 stems the foliage leaves become oriented skyward, by bending of their leaf sheaths and petioles. The aerial vegetative branching system manifests bilateral symmetry and mirror-image symmetry. The inflorescence is a pedunculate umbel. The peduncle culminates in a torus which bears a peripheral whorl of bracts, centripetally situated bracteoles, and pedicellate flowers. Type-1 stems exhibit numerous prickles, which vary from unbranched to branched and from solitary to basally connate in rows.

Genotype-environment interaction on the density of peach buds cultivated in a humid subtropical climate

Studies on the interaction of genetic and environmental effects on floral morphogenesis in peach trees grown in humid subtropical climate provide important information related to adaptation and for assisting in the selection of new cultivars. This study aimed to verify the genetic and environmental effects and to identify peach tree genotypes with greater shoot length, vegetative bud, flower bud density adaptability and stability under humid subtropical climate conditions. Twelve peach tree genotypes were evaluated over a period of eight years, during the growing season (2006/07 to 2013/14) in Pato Branco-PR, Brazil. Data were collected for shoot length (SL), flower bud density (FBD) and vegetative bud density (VBD), as well as temperature, humidity and precipitation. For the analysis of adaptability and stability we used GEE Biplot methodology. SL was influenced by the temperature and relative humidity. Increased exposure time to temperatures below 20 °C and above 30 °C, high thermal amplitude and relative humidity of less than 50% reduced shoot growth. VBD and FBD were predominantly controlled by the genetic factor. For VBD, the genotypes ‘Cascata 1055’ and ‘Conserva 681’ were the most adapted. For FBD, the genotypes ‘Cascata 1055’, ‘BRS Bonão’, ‘Conserva 681’, ‘Cascata 967’ and ‘BRS Kampai’ presented better adaptability. The genotypes more adapted to the FBD can be recommended for cultivation in the humid subtropical climate, since they also present greater stability in the production of fruits, independently of the meteorological conditions that occur during the vegetative and reproductive season.

Does propagation method affect the field performance of peach trees?

Worldwide, peach propagation has been performed mainly by grafting scions of desirable cultivars on rootstocks obtained from seeds. There are, however, other potential propagation methods not widely adopted due to the limited reports on the field performance of the resultant trees. This study addressed this knowledge gap and investigated the field performance of peach trees of the cultivar Maciel that were established in an orchard (5.0 m × 1.4 m spacing) in 2011. The trees were trained in a "Y" system, with seedlings from three propagation techniques: 1) Conventional System (CS) - vegetative bud grafting of the scion on the rootstock of the Okinawa cultivar obtained from seed; 2) Rootstock by Minicutting (RM) - vegetative bud grafting of the scion on the rootstock of the Okinawa cultivar obtained by minicutting in a semi-hydroponic system; 3) Self-Rooting (SR) - self-rooting of the scion in a semi-hydroponic system. The vegetative, productive, and fruit quality parameters were assessed during 2012 and 2013. The Maciel peach trees that were propagated by the SR technique were found to have similar or even superior field performance to those propagated by the CS. The RM propagation method was also found to be an important potential alternative to peach propagation, since this it combines two techniques (cutting and grafting) to reduce tree vigor, especially if the goal is high-density planting.

Does propagation method affect the field performance of peach trees?

Worldwide, peach propagation has been performed mainly by grafting scions of desirable cultivars on rootstocks obtained from seeds. There are, however, other potential propagation methods not widely adopted due to the limited reports on the field performance of the resultant trees. This study addressed this knowledge gap and investigated the field performance of peach trees of the cultivar Maciel that were established in an orchard (5.0 m × 1.4 m spacing) in 2011. The trees were trained in a "Y" system, with seedlings from three propagation techniques: 1) Conventional System (CS) - vegetative bud grafting of the scion on the rootstock of the Okinawa cultivar obtained from seed; 2) Rootstock by Minicutting (RM) - vegetative bud grafting of the scion on the rootstock of the Okinawa cultivar obtained by minicutting in a semi-hydroponic system; 3) Self-Rooting (SR) - self-rooting of the scion in a semi-hydroponic system. The vegetative, productive, and fruit quality parameters were assessed during 2012 and 2013. The Maciel peach trees that were propagated by the SR technique were found to have similar or even superior field performance to those propagated by the CS. The RM propagation method was also found to be an important potential alternative to peach propagation, since this it combines two techniques (cutting and grafting) to reduce tree vigor, especially if the goal is high-density planting.