Vegetative growth
2020
Primo-Millo, Eduardo | Agustí, Manuel | Talón, Manuel
Growth development from seed germination to tree size is reviewed as a chronological sequence of events. Water potential gradient between the seed and the soil moisture and phases of root respiration are preliminary studied for a better understanding of the biosynthesis of hydrolytic enzymes, and the ultrastructural changes taking place in the radicle, plumule, and cotyledons. The polyembryonic characteristic of the seed and its importance in the propagation of citrus complete the first part of the chapter. Juvenility is characterized by the inability of a tree to flower and, thus, to produce. Factors that explain this phenomenon, especially the genetic factors, are described. Reference is made to dormancy. In the Mediterranean climate, it is caused by low temperatures which, in turn, are responsible for floral bud induction. In the tropical climate, it is caused by the lack of water during the dry season. The primary and secondary shoot growth, the development and abscission of leaves, and the bud sprouting and its control are reviewed. Similarly, root development is also revised. The chapter ends with a reference to dwarfing rootstocks, and how they affect the tree size, and a brief review on the use of growth retardants.
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