Vine Biology and Function Presented by Mary Retallack for - PowerPoint PPT Presentation

Vine Biology and Function Presented by Mary Retallack for

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We will cover the following topics • Cell structure and function • Types of plant tissues (meristematic, dermal, photosynthetic, cortex and vascular) • Grapevine Anatomy (roots, shoots, buds, leaves, flowering, fruit development) • Photosynthesis, Translocation, Transpiration, Respiration And how this relates to vineyard management!

Introductions • What would you like to find out more about today?

What is currently happening in the vineyard?

Growth (Meristematic) tissue • Meristematic cells divide to make more cells, allowing the vine to grow. • They occur in the buds, root tips and shoot tips.

Growth (Meristematic) tissue • The cambium layer of the vine stem is an example of a secondary meristem because it enables organs to grow in thickness. When it is cut (damaged) it produces callus tissue.

Wood (inner) and Bark (outer) Cells Wood contains two main cell types • Xylem cells, through which water and nutrients flow • Ray (parenchyma) cells , which store food (starch and proteins) Bark contains two different cell types • Phloem through which sugars and other nutrients move from one part of the vine to another • Cork (phellum) cells which protect the vines inner tissues.

Protection (dermal cells) • Outermost layer of cells (epidermis) • The bark of the vine protects the inner cells from physical damage, pest invasion and winter loss. • The epidermis of leaves and stems may contain guard cells and hairs.

Photosynthetic Tissue • Chloroplasts are the sugar producing cells (mainly found in leaves). • The chlorophyll in these cells enables the process of photosynthesis to occur.

Parenchyma (storage cells) • Living cells with large central vacuoles (storage of substances) and thin but flexible cell walls • They form the cortex and pith of stems, the cortex of roots, the pulp of fruits and the mesophyll of leaves (containing chloroplasts).

Collenchyma (living outer most cells) • These cells form a complete cylinder around the stem • Elongated cells with thicker cell walls (cellulose) providing strength and flexibility to stems and leaves

Sclerenchyma (support cells) • Similar to collenchyma cells but have additional lignin fibres in their cell walls which add strength and support to the plan body. • As these fibres mature and die they leave a hard skeleton of lignin fibres.

Vascular (conducting tissue) Xylem • Xylem Conveys water and dissolved minerals upward from roots into the shoot • Consisting of elongated cells called tracheids and vessel elements along with supporting fibres and parenchyma cells. • The vessel walls contain perforations connected to the next vessels in the line (which facilitate the movement of water and dissolved substances).

Vascular (conducting tissue) Phloem • Phloem is the food or sugar conducting tissue located on the inside of the bark. • Vertical rows of sieve tubes along with supporting fibres and parenchyma cells. • A sieve tube plates connect each sieve tube and controls the direction and flow of dissolved substrates. • The movement of this sugar is always away from the production site to a ‘sink’ or where it is to be utilised.

Dormant Ramsay cutting • Section showing the small, thin walled cells of the cambium • The large sieve tube cells and the thick-walled fibre cells of the phloem and xylem, • The ray cells which in the xylem contain starch grains and • The large water-conducting xylem vessel cells.

Anatomy of Vitis vinifera cane (A) and root (B) • Although the internal structure of the vascular cylinder (phloem, xylem and pith) is similar in Vitis stems and roots, the relations of the various tissues in the vascular cylinder differ considerably. rh – rhytidoma (dead bark); co – dead cortex; ca – cambium; pe – periderm; phf – phloem fibres; pefi – perivascular fibres; ph – phloem; x – xylem; pi – pith, 11 – medullary ray; and px – residues of the primary xylem

Anatomy of Vitis vinifera cane (A) and root (B) perivascular fibres The anatomy of one year old cane (A) can easily be distinguished from that of one year pith old root (B) bark Medullary rays • Its strikingly larger pith phloem • It’s numerous and narrower medullary rays • Its narrower phloem section • The presence of perivascular fibres outside each vascular bundle rh – rhytidoma (dead bark); co – dead cortex; ca – cambium; pe – periderm; phf – phloem fibres; • The presence of a thick dead bark pefi – perivascular fibres; ph – phloem; x – xylem; pi – pith, 11 – medullary ray; and px – residues of the primary xylem

Support and Vascular tissue of a stem/cane

Support and Vascular tissue of root

Root distribution and function • Main roots, lateral roots and feeder roots . • Feeder roots are formed regularly during the growing season, short lived, and provide the large absorption surface needed to supply the vine with its nutrients and water.

Root distribution and function Each root has at its end a yellow coloured region less than 2.5 cm long containing the absorption zone below this is the • zone of elongation • growing point • root cap

Zone of maturation Zone of elongation Zone of cell division

The Casparian strip controls water movement into the vascular cylinder of the root

Root functions Anchorage Water and nutrient absorption • Dissolved nutrients in the soil solution are absorbed by the roots and diffuse into the vascular tissue ( xylem) • Uptake of these nutrients depends on their concentration and mobility in the soil, the uptake rate of the particular grape variety and the soil temperatures (optimum 25-30 o C). • Role of mychorrizal fungi

Arbuscular mycorrhizal root system and hyphae • Beneficial organisms that colonize plant roots • Assist in the update of nutrients (Phosphorous) • Improve drought tolerance • Improve resistance to certain fungal diseases

Root functions Storage of reserves • In late summer and autumn, carbohydrates are transferred for storage in the root system to provide food reserves for the future season’s growth. Hormone production • Hormone production (gibberellin and cytokinin) by the roots influences growth and development of the shoots and clusters of the grapevine.

6 Root Distribution • Most of the roots are concentrated in the top metre of the soil directly under the vine canopy.

Apical meristem Shoots • A shoot is the succulent stem bearing the leaves, tendrils and flower clusters (inflorescences) all of the information required to grow a shoot is contained within a bud.

Leaf Function • Leaves undergo a gradual transition from importing photosynthetic products to export (at approximately 30-50% of the maximal size). Full leaf expansion may take between 30 to 40 days. • Photosynthetic products from grapevine leaves are exported to the developing apex and clusters. • Following harvest/fruit removal, the majority of photosynthates are directed towards and stored in the roots. • Leaf fall or senescence normally begins in late autumn when minerals are translocated (remobilised) back into the canes and trunk.

Compound and prompt buds • Each compound bud contains three partially developed shoots (primary, secondary and tertiary latent buds) enclosed in small leaf like structures called bracts which develops in the leaf axil. • A lateral shoot (summer lateral) grows from a prompt bud in the leaf axil. • The prompt bud will grow into a lateral shoot in the same season that it completes its development. The lateral shoot develops soon after the leaf at the same node has expanded.

Grapevine reproductive development A) A developing latent bud showing an early stage of uncommitted primordium production. B) A later stage showing an uncommitted primordium, a leaf- opposed primordium, that has separated from the shoot apical meristem. C) A dormant latent bud with an inflorescence primordium on the flank of the shoot apex. D) A dissected shoot tip with an immature tendril showing two branches. E) The structures found in the axil of a grape leaf. F) The typical architecture of Vitis Vinifera shoots originating from latent buds (Gibbard et al, 2003 pg 594).

Formation of grapevine flowers (3 stages) - Anlagen • Anlagen (uncommitted primordia) • May develop into inflorescence primordia, tendril primordia or shoot primordia. • Hormones • Giberellin (GA) applied to inflorescence primordia can convert them to tendril like structures. • Cytokinin can be used to induce inflorescence formation in place of tendrils.

Formation of grapevine flowers (3 stages) - Inflorescence primordia • The formation of inflorescence primordia takes place if the anlage undergoes repeated branching to develop many rounded branch primordia. Stages in inflorescence development, May 2006 (left) and August 2006 (right) (Heaslewood, PowerPoint Presentation)