Citrus general information

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Fruit anatomy, fruit and leaf absission zones

Plant Compoments

• Fruit MeSH Citrus fruit is considered a berry because it has many seeds (pips), is fleshy, soft and develops from a single ovary; (this specific type of berry is called hesperidium - a berry with leathery rind). Citrus fruit is characterized by non-climacteric development.
  • Pericarp Tissue surrounding a seed that develops from the ovary wall of the flower.
    • Rind Also peel or exocarp; orange
      rind contains numerous pits
      containing volatile oil glands.
      • Albedo Mesocarp; a spongy white
        tissue on the inside of the rind. Albedo consists of spongy layers of perenchymatus cells rich of glycosides (flavanones). Pectin and pectic enzymes make it bitter. The thread-like vascular bundles run from the albedo along the fruit's axis forming a network outside the carpels. They are rich in peroxidase.
      • Flavedo Or epicarp; external
        colored part of the rind.
    • Pulp A fleshy interior (endocarp) of the citrus fruit
      • Carpel Sections of the citrus fruit
      • Juice sac Juice-filled vesicle, which
        is specialized hair cell.
  • Seed
• Abscission
  zone A distinct process that culminates in the shedding of plant parts due to a series of physiological and biochemical events that lead to cell wall breakdown in the few rows of cells on either side of the fracture line and, ultimately, to detachment of the organ; mature citrus fruits require unusually large forces to remove them from the tree, and this has been an obstacle to efficient and economical mechanical harvesting; it is why citrus fruit abscission and its regulation attracts much attention of researches.
  • Leaf
    abscission
    zone
    • Branch
      abscission
      zone This AZ is located between the branch and the petiole.
    • Laminar
      abscission
      zone This AZ is located between the petiole and the leaf blade.
  • Fruit
    abscission
    zone
    • Abscission
      zone A This AZ is located between the branch and the fruit penduncle.
    • Abscission
      zone C this AZ is located in the fruit calix (cup-like structure at the end of the fruit where the fruit is attached to the penduncle).

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Orange fruit anatomy

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Absission zones

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References

• Iglesias DJ et al. Physiology of citrus fruiting. Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias, Apdo.Nov. 2007 (.pdf)