The Science of Grapevines

Markus Keller

• Publisher: Academic Press
• Year: 2020
• ISBN:
  9780128167021
• Edition: 3
• Topic: Tecnologia e ingegneria
• Subtopic: Agricoltura

The Science of Grapevines, Third Edition reflects the latest insights into cultivar relationships, vascular transport, hormone action, and stress responses of grapevines. Based on the author's many years of teaching, research and practical experience with grapevines and grape production, the book is completely revised and updated, presenting a comprehensive introduction on the physical structure of the grapevine, its organs, their functions, and their environmental interactions. While many concepts discussed are broadly applicable to plants in general, the focus is on grapevines, especially cultivated grapevines. This book enables readers to use these concepts in their own scientific research or in practical production systems.

Scientifically grounded and integrating discoveries in other plant species, the book explores the physiological processes underlying grapevine form and function, their developmental and environmental control, and their implications for practical vineyard management.

• Improves user understanding of the impact of their management decisions and cultural practices
• Enables prediction of the consequences of actions in the vineyard and the diagnosis and mitigation of potential problems before they threaten the sustainability of grape production
• Includes specific insights on canopy-environment interactions, yield formation, sources of variation in fruit composition and environmental constraints

Chapter 1

Taxonomy and anatomy

Abstract

The diverse species of grapevine belong to the botanical family Vitaceae, which includes mostly shrubs and woody lianas that climb using leaf-opposed tendrils. The vast majority of the thousands of grape cultivars belong to the species Vitis vinifera. Some of the other species are used as pest-tolerant rootstocks to which cultivars with desirable fruit properties are grafted. Cultivars are propagated asexually as cuttings so that each individual is a clone of its mother plant. Grapevines comprise vegetative organs (roots, trunk, cordon, shoots, leaves, and tendrils) and reproductive organs (clusters with flowers or berry fruit). All organs are interconnected through the vascular system comprising the xylem for water and nutrient transport, and the phloem for assimilate transport. The roots form the plant–soil interface, while the trunk, cordons, and shoots of a vine form its stem. The shoots carry the leaves, buds, tendrils, and clusters. Leaves are arranged in spiral phyllotaxy in juvenile vines and in alternate phyllotaxy in mature vines. Buds are young, compressed shoots embedded in leaf scales. Tendrils and clusters are modified shoots. After fertilization, the flower pistil develops into the berry fruit. The berry houses up to four seeds surrounded by the endocarp, the mesocarp or flesh, and the exocarp or skin.

Keywords

Bud; Clone; Cultivar; Grape berry; Leaf; Root; Rootstock; Shoot; Tendril; Vitis

Chapter outline

• 1.1 Botanical classification and geographical distribution
  • Domain Eukaryota
  • Kingdom plantae
  • Division (synonym phylum) Angiospermae (synonym Magnoliophyta)
  • Class dicotyledoneae (synonym Magnoliopsida)
  • Order vitales (formerly Rhamnales)
  • Family Vitaceae
  • Genus Muscadinia
  • Genus Vitis
  • American group
  • Eurasian group
• 1.2 Cultivars, clones, and rootstocks
  • 1.2.1 Variety versus cultivar
  • 1.2.2 Cultivar classification
  • 1.2.3 Clones
  • 1.2.4 Rootstocks
• 1.3 Morphology and anatomy
  • 1.3.1 Roots
  • 1.3.2 Trunks and shoots
  • 1.3.3 Nodes and buds
  • 1.3.4 Leaves
  • 1.3.5 Tendrils and clusters
  • 1.3.6 Flowers and grape berries

1.1 Botanical classification and geographical distribution

The basic unit of biological classification is the species. According to the “biological species concept,” a species is defined as a community of individuals—that is, a population or group of populations whose members can interbreed freely with one another under natural conditions but not with members of other populations (Mayr, 2001; Soltis and Soltis, 2009). In other words, such communities are reproductively isolated. Although each individual of a sexual population is genetically unique, each species is a closed gene pool, an assemblage of organisms that do not normally exchange genes with other species. Their genes compel the individuals belonging to a species to perpetuate themselves over many generations. Yet all life forms on Earth are interrelated; they all ultimately descended from a common ancestor and “dance” to the same genetic code, whereby different combinations of three consecutive nucleotides of each organism’s deoxyribonucleic acid (DNA) specify different amino acids that can be assembled into proteins. Because they are thus interrelated, organisms can be grouped according to the degree of their genetic similarity, external appearance, and behavior. In the classification hierarchy, closely related species are grouped into a genus, related genera into a family, allied families into an order, associated orders into a class, similar classes into a division (plants) or a phylum (animals), related divisions or phyla into a kingdom, and, finally, allied kingdoms into a domain. The “evolutionary species concept” recognizes this ancestor–offspring connection among populations that may follow distinct evolutionary paths to occupy separate ecological niches but may continue to interbreed for some time (Soltis and Soltis, 2009). For example, although they have been geographically isolated for over 20 million years, Eurasian and North American Vitis species are still able to interbreed readily.

As is the case with many plants, the species of the genus Vitis are not very well defined because of the extreme morphological variation among and within populations of wild vines (Currle et al., 1983; Hardie, 2000; Mullins et al., 1992). This implies the following: (i) all Vitis species are close relatives that share a relatively recent common ancestor and (ii) evolution is still at work, throwing up new variants all the time (see Section 2.3). Many vine species are actually semispecies—that is, populations that partially interbreed and form hybrids under natural conditions, which is in fact common among plants and may be an important avenue for the evolution of new species (Aradhya et al., 2013; Soltis and Soltis, 2009). Despite some hybridization where their natural habitats overlap, however, the various Vitis gene pools usually stay apart so that the populations remain recognizably different. Nonetheless, species that occur in close proximity are more similar than distant species in similar habitats. Grapevines are a good example of the limits of taxonomic systems. They demonstrate that there is a continuum of differentiation rather than a set of discrete, sexually incompatible units.

As early as 1822, the Rev. William Herbert asserted that “botanical species are only a higher and more permanent class of varieties,” and in 1825 the geologist Leopold von Buch postulated that “varieties slowly become changed into permanent species, which are no longer capable of intercrossing” (both cited in Darwin, 1859). A few decades later, Charles Darwin expressed it clearly: “Wherever many closely allied yet distinct species occur, many doubtful forms and varieties of the same species likewise occur” and, furthermore, “there is no fundamental distinction between species and varieties,” and, finally, “varieties are species in the process of formation” (Darwin, 1859). Indeed, > 150 years after the first publication of Darwin’s revolutionary insights, modern genetic research has confirmed that the various Vitis species evolved within the last 18 million years from a common ancestor (Aradhya et al., 2013; Péros et al., 2011; Wan et al., 2013; Zecca et al., 2012). They have not yet developed the complete reproductive isolation that normally characterizes biological species. Thus, Vitis species are defined as populations of vines that can be easily distinguished by morphological traits, such as the shape and size of their leaves, flowers, and berries, and that are isolated from one another by geographical, ecological, or phenological barriers; such species are termed ecospecies (Hardie, 2000; Levadoux, 1956; Mullins et al., 1992). The following is a brief overview of the botanical classification of grapevines, starting with the domain and finishing with a selection of species.

Domain Eukaryota

All living beings, making up the Earth’s biological diversity or biodiversity, are currently divided into three great domains of life: the Bacteria, the Archaea, and the Eukaryota. The Eukaryota (eukaryotes; Greek eu = true, karyon = nucleus) include all terrestrial, sexually reproducing “higher” organisms with relatively large cells (10–100 μm) containing a true cell nucleus, in which t...