The Genus Citrus

Front Cover
The Genus Citrus
Copyright
Contents
Contributors
Chapter 1: The citrus genome
	1.1  Concept of genome
	1.2  Citrus genomes
	1.3  Genomes: Pure, admixed, and domesticated
		1.3.1  Inference of pure and admixed genome regions
		1.3.2  Identification of the ancient progenitor citrus species
		1.3.3  A whole-genome perspective of citrus hybrids and admixtures
		1.3.4  Comparative analyses of citrus genomes: The example of evolution and domestication of mandarins
	References
	Further reading
Chapter 2: The origin of citrus
	2.1  The mythological origin of citrus
	2.2  The origin of citrus
		2.2.1  The concept of citrus
		2.2.2  Phylogeny of citrus pure species
		2.2.3  Genealogy of cultivated citrus
		2.2.4  Paleontology of citrus
		2.2.5  Chronology of citrus speciation
		2.2.6  Biogeography of citrus
		2.2.7  The center of origin of citrus
	2.3  Citrus radiation and evolution
		2.3.1  Citrus radiation
		2.3.2  Late Miocene: Global cooling and the Southeast Asian radiation
		2.3.3  Dispersal routes of ancestral citrus
		2.3.4  Early Pliocene: Wallacea orogeny and the dispersal of Australian limes
		2.3.5  Early Pleistocene: Glacial maxima and the diversification of mandarins
	2.4  A new evolutionary framework for the genus Citrus
	Acknowledgments
	References
Chapter 3: Domestication and history
	3.1  The taxonomy, cultivars, and genetic origin of citrus
		3.1.1  The taxonomy and the true citrus group
		3.1.2  The genetic origin of some hybrid citrus
	3.2  The cultivation history and distribution of citrus
		3.2.1  Ancient Chinese citrus
			3.2.1.1  The citrus taxonomy and varieties in ancient China
			3.2.1.2  The distribution of citrus in ancient China
			3.2.1.3  The spiritual symbol, medicinal value, and management of citrus in ancient China
			3.2.1.4  Wild citrus in China
		3.2.2  Ancient citrus in Japan
			3.2.2.1   Citrus tachibana (Tachibana)
			3.2.2.2   Citrus depressa (Shiikuwasha)
		3.2.3  Ancient citrus in India
			3.2.3.1  History, distribution, and origin of ancient citrus in India
			3.2.3.2  Citrus indica
			3.2.3.3  Citrus macroptera
			3.2.3.4  Citrus latipes
			3.2.3.5  Citrus assamensis
			3.2.3.6   Citrus megaloxycarpa Lushaigton (Sour Pummelo)
			3.2.3.7  Citrus limettioides
			3.2.3.8  Citrus limetta
			3.2.3.9  Ancient member of Citrus sinensis
		3.2.4  The origin, spread, and introduction of citrus
		3.2.5  The genetic diversity of Citrus
			3.2.5.1  The genetic diversity of semiwild, cultivated, and garden-yard citrus
			3.2.5.2  The genetic diversity of wild and semiwild citrus
	References
Chapter 4: Citrus taxonomy
	4.1  The genus Citrus definition
		4.1.1  The botanical treatment of the genus Citrus
		4.1.2  Phenotypical traits of the true Citrus
			4.1.2.1  Morphological characteristics of the genus Citrus (sensu Swingle)
			4.1.2.2  Traits of the related species of the true citrus
		4.1.3  Reproductive biology, cytogenetics and molecular data, and the definition of the genus Citrus
			4.1.3.1  The genus Citrus and the biological concept of species; genus or species
			4.1.3.2  Sexual compatibility and phylogenetic relationships with related genera of the true citrus; toward a new defin ...
	4.2  The genus Citrus classifications; an historical, biological, genetic, and phylogenomic perspective
		4.2.1  The history of citrus botanical classifications
			4.2.1.1  The early classifications
			4.2.1.2  The 20th-century classifications
		4.2.2  1967–2017, from traditional taxonomy to phylogenomy: 50  years to clarify the genetic organization of the genus ...
		4.2.3  The ancestral and admixture taxa
			4.2.3.1  Pure Citrus species
			4.2.3.2  Admixture types
				Bispecific admixture
				Complex tri and tetraspecific admixtures
	4.3  Phenotypic diversity structure strongly reflects evolutionary history
		4.3.1  Reticulate evolution, apomixis, and the correlation between the structures of genetic and phenotypic diversities ...
		4.3.2  Traits of the four Asian ancestral taxa of the edible Citrus ( Fig. 4.8)
			4.3.2.1   C. maxima (Burm.) Merri
			4.3.2.2   C. medica L.
			4.3.2.3   C. micrantha Wester
			4.3.2.4   C. reticulata Blanco
		4.3.3  Traits of some modern citrus taxa resulting from admixture
	4.4  Conclusion
	References
Chapter 5: Commercial scion varieties
	5.1  Pummelos/shaddocks ( Citrus maxima)
		5.1.1  Principal commercial pummelo varieties
			5.1.1.1  White-fleshed pummelo varieties
		5.1.2  Pigmented pummelo varieties
			5.1.2.1  Lightly pigmented pummelo varieties
			5.1.2.2  Highly pigmented pummelo varieties
		5.1.3  Pummelo hybrids
	5.2  Grapefruit ( Citrus paradisi)
		5.2.1  Principal commercial varieties
			5.2.1.1  White-fleshed grapefruit varieties
				Marsh (syn. Marsh seedless)
			5.2.1.2  Pigmented grapefruit varieties
				Pink-fleshed grapefruit varieties
				Red-fleshed grapefruit varieties
			5.2.1.3  Grapefruit-like hybrids
	5.3  Lemons ( Citrus limon)
		5.3.1  Principal commercial varieties
	5.4  Limes ( Citrus aurantiifolia a and Citrus latifolia)
	5.5  Oranges ( Citrus sinensis)
		5.5.1  Sugar or acidless orange varieties
		5.5.2  Blood or pigmented orange varieties
		5.5.3  Navel oranges
		5.5.4  Common orange varieties
	5.6  Mandarins ( Citrus reticulata)
		5.6.1  Principal commercial mandarin varieties
		5.6.2  Other mandarin hybrids of current or potential commercial importance
	References
	Further reading
Chapter 6: Citrus rootstocks
	6.1  Introduction
	6.2  Reasons for a rootstock
	6.3  Important rootstock attributes
	6.4  Rootstock use by region
	6.5  The major rootstocks
	6.6  Rootstock trends and future prospects
	Acknowledgments
	References
	Further reading
Chapter 7: Traditional breeding
	7.1  Introduction
	7.2  Scion breeding
		7.2.1  Somatic mutations and chimeras
		7.2.2  Nucellar selections
		7.2.3  Hybridization
			7.2.3.1  Diploid breeding
			7.2.3.2  Interspecific crosses with wild relatives to introgress resistance genes or other useful traits
			7.2.3.3  Triploid breeding
		7.2.4  Mutation breeding
	7.3  Rootstock breeding
		7.3.1  Objectives
		7.3.2  Conventional methods to generate new rootstocks
		7.3.3  Propagation
		7.3.4  Phenotyping methods for diseases and abiotic stress resistance before field trials
		7.3.5  Rootstock trials
	7.4  Perspectives
	References
Chapter 8: Genomic breeding
	8.1  Introduction
	8.2  DNA markers
		8.2.1  Types of DNA markers
		8.2.2  SSR and indel markers
		8.2.3  SNP markers
		8.2.4  RFLP and CAPS markers
		8.2.5  NGS-based high-throughput genotyping
	8.3  Linkage mapping analysis toward MAS
		8.3.1  Linkage-map construction using transferrable DNA markers
		8.3.2  DNA-marker development for monogenic traits
		8.3.3  Polyembryony
		8.3.4  Fruit traits
		8.3.5  Aroma
		8.3.6  Disease, stress resistance, and other traits
	8.4  MAS for complex traits
		8.4.1  QTL analysis of complex traits
		8.4.2  Linkage disequilibrium (LD) analysis
		8.4.3  Association mapping (AM) analysis
		8.4.4  Genomic selection (GS)
	8.5  Future trends
	References
Chapter 9: Citrus biotechnology
	9.1  Introduction
	9.2  Micropropagation
	9.3  Organogenesis and rooting
	9.4  Gametic embryogenesis
	9.5  Somaclonal variation
	9.6  Allotetraploids via somatic hybridization
	9.7  Somatic cybridization
	9.8  Molecular marker development for Alternaria brown spot disease
	9.9  Reducing juvenility via viral vectors
	9.10  Genetic transformation of citrus
	9.11  Direct DNA incorporation into citrus
		9.11.1  Protoplast transformation
		9.11.2  Particle bombardment/biolistics
		9.11.3   Agrobacterium -mediated transformation of citrus
	9.12  CRISPR gene editing
	9.13  Concluding remarks
	References
Chapter 10: Vegetative growth
	10.1  Seed germination
		10.1.1  Imbibition of water
		10.1.2  Breathing
		10.1.3  Protein synthesis
		10.1.4  Mobilization of the reserves contained in cotyledons
			10.1.4.1  Reserve compounds
			10.1.4.2  Ultrastructural location of reserves
			10.1.4.3  Transformation of reserve compounds
				10.1.4.3.1  Metabolization of cotyledon lipids during germination
				10.1.4.3.2  Mobilization of cotyledon proteins during germination
				10.1.4.3.3  Changes in the hydrocarbon fractions of cotyledons during germination
			10.1.4.4  Ultrastructural changes in the cotyledons during germination
		10.1.5  Seedling development
		10.1.6  Polyembryony
		10.1.7  Juvenile characters
	10.2  Dormancy and vegetative activity
	10.3  Development of the canopy
		10.3.1  Stem growth
		10.3.2  Secondary stem growth
		10.3.3  Sprouting development
		10.3.4  Factors affecting vegetative development
	10.4  Leaf development
		10.4.1  Leaf abscission
			10.4.1.1  Abscission zones
			10.4.1.2  The abscission process
			10.4.1.3  Anatomical and ultrastructural changes in the abscission layer
	10.5  Formation of the root system
		10.5.1  Development of the primary root
			10.5.1.1  The calyptra or root cap
			10.5.1.2  The apical meristem of the root
			10.5.1.3  Elongation zone
			10.5.1.4  Maturation zone
		10.5.2  Lateral root development
		10.5.3  Secondary root growth
		10.5.4  Root distribution
		10.5.5  Factors affecting root development
	10.6  Trees of reduced size
	10.7  Control of vegetative development through the use of growth retardants
	References
Chapter 11: Flowering and fruit set
	11.1  The process of flowering
	11.2  Type of inflorescences
	11.3  Control of flowering
		11.3.1  Environmental control
			11.3.1.1  Temperature
			11.3.1.2  Water stress
		11.3.2  Other factors affecting flowering
			11.3.2.1  Citrus cultivar
			11.3.2.2  State and age of plants
			11.3.2.3  Carbohydrate content
			11.3.2.4  Nutritional status
			11.3.2.5  Source of nitrogen
			11.3.2.6  The influence of fruit on flowering
		11.3.3  Control of flowering
			11.3.3.1  The application of gibberellic acid
			11.3.3.2  Water deficit
			11.3.3.3  Girdling or ringing branches
	11.4  Pollination and fertilization
	11.5  Fruit set
	11.6  Parthenocarpy
	11.7  Endogenous regulation of fruit set
		11.7.1  Influence of hormone levels
			11.7.1.1  Gibberellins
			11.7.1.2  Auxins
			11.7.1.3  Abscisic acid
			11.7.1.4  Cytokinins
		11.7.2  Competition for photoassimilates
		11.7.3  Interactions between hormones and photoassimilates
	11.8  Factors affecting fruit set
		11.8.1  Temperature
		11.8.2  Irrigation
		11.8.3  Nitrogen fertilization
		11.8.4  Mineral deficiencies
		11.8.5  Flowering intensity
		11.8.6  Position of the flower in the tree
	11.9  Improvement of fruit set: Cultural practices
		11.9.1  The application of GA 3
		11.9.2  Girdling or ringing
		11.9.3  Treatment with GA 3 combined with girdling
		11.9.4  Other practices that favor fruit set
			11.9.4.1  Flowering control
			11.9.4.2  Irrigation and fertilization
			11.9.4.3  Pruning
			11.9.4.4  Arching of branches
	11.10  Fruit development
	11.11  Factors affecting fruit development
		11.11.1  Endogenous factors
			11.11.1.1  Genetic potential of the fruit
			11.11.1.2  Hormone levels
		11.11.2  Tree age
		11.11.3  Fruit position on the tree
		11.11.4  Foliar area
		11.11.5  Seed number
		11.11.6  Flowering intensity
		11.11.7  Competition among developing fruits
		11.11.8  Environmental factors
			11.11.8.1  Temperature
			11.11.8.2  Relative humidity
		11.11.9  Cultural practices
			11.11.9.1  Irrigation
			11.11.9.2  Fertilization
			11.11.9.3  Treatments for setting
	11.12  Techniques to improve fruit size
		11.12.1  Pruning
		11.12.2  Manual thinning
			11.12.2.1  Manual thinning at random
			11.12.2.2  Selective manual thinning
		11.12.3  Chemical thinning
			11.12.3.1  Inhibition of flowering
			11.12.3.2  Fruitlet abscission
			11.12.3.3  Application of synthetic auxins
		11.12.4  Girdling or ringing
	11.13  Seed development
	References
	Further reading
Chapter 12: Fruit growth and development
	12.1  The long, complex, and intriguing journey from set fruitlets to ripe fruit
	12.2  The fruit of citrus is a modified berry called hesperidium
		12.2.1  The fruit rind or peel provides an interface of the fruit with the external environment
		12.2.2  The fleshy pulp is composed of segments, which contain the juice vesicles
		12.2.3  Vascular system of the citrus fruit
	12.3  Citrus fruit dimensions are genetically determined but are influenced by environmental and cultural practices
	12.4  Metabolism and accumulation of carbohydrate and organic acids, determinants of fruit flavor quality
		12.4.1  The physiology and practical aspects of carbohydrate and organic acid accumulation
		12.4.2  The genetic basis of BRIX and TA
		12.4.3  The biochemistry of carbohydrate and organic acid accumulation
			12.4.3.1  Sugar transport, metabolism, and accumulation
			12.4.3.2  Synthesis, accumulation, and catabolism of citric acid
			12.4.3.3  Citrate and proton homeostasis in the vacuole, and their transport
		12.4.4  Contribution of Omics techniques to the understanding of sugar and acid metabolism and accumulation
	12.5  Color change during fruit development and ripening
		12.5.1  Biochemical, molecular, and structural changes related to chlorophylls and carotenoids
		12.5.2  Environmental, nutritional, and hormonal cues affecting chlorophylls and carotenoids
		12.5.3  General aspects of blood oranges during fruit development and ripening
			12.5.3.1  Environmental factors controlling anthocyanin accumulation in fruit
			12.5.3.2  Potential targets to control purple pigmentation of blood oranges
	12.6  Preharvest drop impacts on and determines, respectively, citrus fruit production and harvesting time
	12.7  Transcriptome evolution during ripening: A next-generation view
	12.8  Future perspective: Basic knowledge and advanced techniques should result in improved products
	Author contribution
	References
Chapter 13: Citrus in changing environments
	13.1  Limitations to geographical expansion of citrus
	13.2  Predicted climate in citrus growing regions
		13.2.1  Mediterranean climates
		13.2.2  Humid subtropics
		13.2.3  Semiarid regions
		13.2.4  Overall climate trends in citrus-producing regions
	13.3  Citrus responses to climate-influenced environmental factors
	13.4  Soil moisture
		13.4.1  Optimal water requirements in citrus
		13.4.2  Flooding
		13.4.3  Management of soil flooding in citrus orchards
		13.4.4  Water deficit—Effects on crop productivity
		13.4.5  Irrigation to mitigate water deficit
	13.5  Soil salinity
		13.5.1  Salinity effect on vegetative and reproductive growth
		13.5.2  Salinity effects on mineral nutrition
		13.5.3  Salinity effects on citrus physiology
		13.5.4  Mitigation of salinity effects
	13.6  Air moisture
	13.7  Temperature
		13.7.1  Heat
		13.7.2  Mechanisms involved in heat tolerance
		13.7.3  Management of high temperature and breeding heat-tolerant varieties
		13.7.4  Chilling and freezing
		13.7.5  Management of freezing temperature in citrus orchards
		13.7.6  Mechanisms involved in chilling and freezing tolerance
		13.7.7  Breeding cold-tolerant varieties
	13.8  Increased carbon dioxide
		13.8.1  Effects of CO 2 on overall growth and photosynthesis
		13.8.2  Effects on partitioning and growth habit
		13.8.3  Interactions with other abiotic stresses
		13.8.4  Maximizing benefits of increased [CO 2 ]
	13.9  Conclusions
	Acknowledgments
	References
	Further reading
Chapter 14: Salinity and water deficit
	14.1  Introduction
	14.2  Salinity
		14.2.1  Salinity components
			14.2.1.1  Osmotic component
			14.2.1.2  Ion-toxicity component
		14.2.2  Salinity avoidance mechanisms
			14.2.2.1  Differences between genotypes and breeding programs
			14.2.2.2  Sodium exclusion
			14.2.2.3  Chloride nutrition
				14.2.2.3.1  Cl − homeostasis in citrus
			14.2.2.4  Molecular mechanisms regulating xylem Cl − translocation
			14.2.2.5  Morphophysiological factors and ploidy level
		14.2.3  Citrus responses to salinity
			14.2.3.1  Global gene expression
			14.2.3.2  Hormone regulation
	14.3  Water deficit
		14.3.1  Resistance mechanisms and differences among genotypes
			14.3.1.1  Ploidy level
		14.3.2  Citrus responses to water deficit
			14.3.2.1  Perception and hormonal regulation
			14.3.2.2  Global responses
	14.4  Resistance and tolerance mechanisms common to water deficit and salinity
		14.4.1  Osmotic adjustment and synthesis of compatible osmolytes
		14.4.2  Antioxidant defense
		14.4.3  Synthesis of protective proteins
	14.5  Agronomic and biotechnological approaches to improve crop stress resistance
		14.5.1  Agronomic and palliative practices
			14.5.1.1  Agronomic palliatives
			14.5.1.2  Mycorrhizas
			14.5.1.3  Priming
		14.5.2  Molecular approaches
	14.6  Concluding remarks
	References
Chapter 15: Soil and nutrition interactions
	15.1  Introduction
	15.2  Soils of major citrus-producing regions in the world
		15.2.1  Soils of tropical and subtropical regions
		15.2.2  Soils of the Mediterranean and similar regions
	15.3  The role of mineral nutrients in citrus production
		15.3.1  Nitrogen
		15.3.2  Phosphorus
		15.3.3  Potassium
		15.3.4  Calcium, magnesium, and sulfur
		15.3.5  Micronutrients
	15.4  Monitoring soil fertility and plant nutritional status
		15.4.1  Soil analysis
		15.4.2  Plant analysis
	15.5  Nutrient management strategies
		15.5.1  Acidity and alkalinity
		15.5.2  Fertilization with solubles and solids
		15.5.3  Fertigation
		15.5.4  Foliar fertilization
		15.5.5  Organic fertilization
		15.5.6  Fertilization and stress alleviation
	15.6  Concluding remarks
	References
	Further reading
Chapter 16: Citrus pests in a global world
	16.1  Introduction
	16.2  Citrus pest management in Asia
	16.3  Citrus pest management in the Mediterranean basin
	16.4  Citrus pest management in North America
		16.4.1  Florida
		16.4.2  California and Texas
	16.5  Citrus pest management in South America
	16.6  Citrus pest management in Africa
		16.6.1  Production pests
		16.6.2  Cosmetic pests
		16.6.3  Phytosanitary pests
	16.7  Epilogue
	References
Chapter 17: Diseases caused by fungi and oomycetes
	17.1  Greasy spot disease of citrus caused by Zasmidium citri-griseum
		17.1.1  Introduction
		17.1.2  Disease symptoms
		17.1.3  Infection process
		17.1.4  Pathogenicity and virulence
		17.1.5  Disease management
	17.2  Root rot, foot rot, brown rot of fruits, canopy blight, and damping-off diseases of citrus caused by Phytophthor ...
		17.2.1  Introduction
		17.2.2  Disease symptoms
		17.2.3  Infection process
		17.2.4  Pathogenicity and virulence
		17.2.5  Disease management
	17.3  Melanose disease of citrus caused by Diaporthe citri
		17.3.1  Introduction
		17.3.2  Disease symptoms
		17.3.3  Infection process
		17.3.4  Pathogenicity and virulence
		17.3.5  Disease management
	17.4  Citrus black spot disease caused by Phyllosticta citricarpa
		17.4.1  Introduction
		17.4.2  Disease symptoms
		17.4.3  Infection process
		17.4.4  Pathogenicity and virulence
		17.4.5  Disease management
	17.5  Brown spot, leaf spot and black rot diseases of citrus caused by Alternaria
		17.5.1  Introduction
		17.5.2  Disease symptoms
		17.5.3  Infection process
		17.5.4  Pathogenicity and virulence
		17.5.5  Disease management
	17.6  Postbloom fruit drop disease caused by Colletotrichum
		17.6.1  Introduction
		17.6.2  Disease symptoms
		17.6.3  Infection process
		17.6.4  Pathogenicity and virulence
		17.6.5  Disease management
	17.7  Citrus scab diseases caused by Elsinoë
		17.7.1  Introduction
		17.7.2  Disease symptoms
		17.7.3  Infection process
		17.7.4  Pathogenicity and virulence
		17.7.5  Disease management
	17.8  Mal secco disease caused by Plenodomus tracheiphilus
		17.8.1  Introduction
		17.8.2  Disease symptoms
		17.8.3  Infection process
		17.8.4  Pathogenicity and virulence
		17.8.5  Disease management
	References
Chapter 18: Bacterial pathogens of citrus: Citrus canker, citrus variegated chlorosis and Huanglongbing
	18.1  Introduction
	18.2  Citrus canker
		18.2.1  History and background
		18.2.2  Symptoms and epidemiology of ACC
		18.2.3  ACC control through eradication
		18.2.4  Endemic control/mitigation of ACC
		18.2.5  Implications of citrus canker quarantines and trade
	18.3  Citrus variegated chlorosis
		18.3.1  History and background
		18.3.2  Disease management, control, and mitigation
		18.3.3  Recent discoveries and advances
	18.4  Huanglongbing
		18.4.1  History and background
		18.4.2  Symptoms
		18.4.3  Etiology and diagnosis
		18.4.4  Pathogen biology: Phloem restriction in citrus, systemic infection in psyllid, and lack of axenic culture
		18.4.5  Genomics and taxonomy
		18.4.6  Epidemiology: Latency and incubation
		18.4.7  Control/management
	References
	Further reading
Chapter 19: Citrus viruses and viroids
	19.1  Introduction
	19.2   Citrus tristeza virus ( Closterovirus, Closteroviridae)
	19.3   Satsuma dwarf virus ( Sadwavirus, Secoviridae)
	19.4  Citrus leprosis viruses
	19.5   Citrus psorosis virus ( Ophiovirus, Aspiviridae)
	19.6   Citrus tatter leaf virus ( Apple stem grooving virus) ( Capillovirus, Betaflexiviridae)
	19.7   Citrus variegation virus/Citrus leaf rugose virus ( Ilarvirus, Bromoviridae)
	19.8   Citrus leaf blotch virus ( Citrivirus, Betaflexiviridae)
	19.9   Citrus vein enation virus ( Enamovirus, Luteoviridae)
	19.10   Citrus yellow mosaic virus ( Badnavirus, Caulimoviridae)
	19.11   Indian citrus ringspot virus ( Mandarivirus, Alphaflexivirdae)
	19.12   Citrus yellow vein clearing virus ( Mandarivirus, Alphaflexivirdae)
	19.13   Citrus chlorotic dwarf-associated virus ( Geminiviridae)
	19.14   Citrus concave gum-associated virus and Citrus virus A (tentative Coguvirus, Bunyavirales)
	19.15  Diseases of unknown etiology
	19.16  Citrus sudden death -associated virus ( Marafivirus, Tymoviridae)
	19.17  Miscellaneous viruses
	19.18  Citrus exocortis viroid ( Pospiviroid, Pospiviroidae)
	19.19  Hop stunt viroid ( Hostuviroid, Pospiviroidae)
	19.20  Citrus bent leaf viroid ( Apscaviroid, Pospiviroidae)
	19.21  Citrus dwarfing viroid ( Apscaviroid, Pospiviroidae)
	19.22  Citrus viroid V ( Apscaviroid, Pospiviroidae)
	19.23  Citrus viroid VI ( Apscaviroid, Pospiviroidae)
	19.24  Citrus viroid VII (tentative Apscaviroid, Pospiviroidae)
	19.25  Citrus bark cracking viroid ( Cocadviroid, Pospiviroidae)
	19.26  Diagnosis
	19.27  Control
	19.28  Conclusion
	Acknowledgment
	References
Chapter 20: Horticultural practices
	20.1  Grove planning and tree spacing
		20.1.1  Site selection
		20.1.2  Variety and rootstock selection
		20.1.3  Tree spacing
	20.2  Irrigation and water management planning
		20.2.1  Water management
	20.3  Canopy management and tree size control
		20.3.1  Mechanical pruning cuts
			20.3.1.1  Hedging
			20.3.1.2  Topping
			20.3.1.3  Skirting
		20.3.2  Manual pruning
			20.3.2.1  Young tree formation
			20.3.2.2  Young tree training
			20.3.2.3  Clearing internal canopy
			20.3.2.4  Rejuvenating pruning
		20.3.3  Effects of pruning on tree physiology
		20.3.4  Other considerations
	20.4  Crop load management
	References
Chapter 21: Postharvest technology of citrus fruits
	21.1  Introduction
	21.2  Postharvest Physiology
		21.2.1  Responses of citrus fruits to postharvest stress conditions
		21.2.2  Postharvest physiological disorders
			21.2.2.1  Chilling injury
			21.2.2.2  Nonchilling disorders
			21.2.2.3  Oleocellosis
			21.2.2.4  Stylar-end breakdown (SEB) blossom-end clearing (BEC)
			21.2.2.5  Zebra skin
			21.2.2.6  Peel pitting or staining in oranges, mandarins, and grapefruits
			21.2.2.7  Stem-end rind breakdown (SERB)
			21.2.2.8  Peteca of lemons
	21.3  Postharvest pathology
		21.3.1  Main postharvest diseases
		21.3.2  Preharvest and postharvest factors affecting disease incidence
		21.3.3  Disease management strategies
			21.3.3.1  Control with chemical fungicides
			21.3.3.2  Nonpolluting integrated disease management
	21.4  Postharvest handling and storage
		21.4.1  Harvesting and orchard practices
		21.4.2  Packinghouse practices
			21.4.2.1  Ethylene degreening
			21.4.2.2  Fruit cleaning and sanitation
			21.4.2.3  Sorting of citrus fruit according to quality classes
			21.4.2.4  Wax application
			21.4.2.5  Carton box design and ventilation
			21.4.2.6  Moisture loss management
		21.4.3  Transport and international shipment procedures
			21.4.3.1  Temperature management prior to and during shipments
			21.4.3.2  Possible negative impact during cold storage: Pre- and postexport
			21.4.3.3  Treatments to induce cold resistance to prolonged cold storage
		21.4.4  Postharvest quarantine treatments for citrus exports
	References
Chapter 22: Chemistry of citrus flavor
	22.1  Introduction
	22.2  Lemon
		22.2.1  Seasonal changes
		22.2.2  Lemon oil extraction
		22.2.3  Aroma volatiles
		22.2.4  Aldehydes
		22.2.5  Esters
		22.2.6  Terpenoid hydrocarbon
		22.2.7  Alcohols, ketones, and oxygen heterocycles
		22.2.8  Lemon oil sulfur compounds
	22.3  Orange and mandarin
		22.3.1  Aldehydes
		22.3.2  Esters
		22.3.3  Terpenoid hydrocarbons
		22.3.4  Alcohols, ketones, acids, and oxygen heterocycles
		22.3.5  Sulfur- and nitrogen-containing compounds
		22.3.6  Differences between orange and mandarin
	22.4  Grapefruit
	22.5  Conclusion
	References
	Further reading
Chapter 23: Global economics and marketing of citrus products
	23.1  Introduction
	23.2  Sweet oranges
		23.2.1  Sweet orange industry organization in Brazil
		23.2.2  Sweet orange industry organization in Florida
		23.2.3  Trade of fresh sweet oranges
	23.3  Grapefruit and pummelos
	23.4  Mandarins/tangerines
		23.4.1  Production and consumption by country
		23.4.2  Exports and imports by country
		23.4.3  Mandarins/tangerines used for processing by country
	23.5  Lemons and limes
	23.6  Price Determination for citrus
	23.7  Trade agreements and citrus
	23.8  Marketing and promotion of citrus
	23.9  By-products from citrus processing
	References
	Further reading
Chapter 24: Citrus and health
	24.1  Introduction
	24.2  Carotenoid in citrus fruits
		24.2.1  Carotenoid accumulation in citrus fruits
		24.2.2  The metabolism of β -cryptoxanthin in citrus fruits
		24.2.3  The role of β -cryptoxanthin in human health
			24.2.3.1  Serum β -cryptoxanthin levels
			24.2.3.2  Characteristics of β -cryptoxanthin as identified in epidemiological studies
	24.3  Flavonoid in citrus fruits
		24.3.1  Flavonoid composition in citrus fruits
		24.3.2  Heath benefits of citrus flavonoids
			24.3.2.1  Citrus flavanone hesperidin and its biological properties
			24.3.2.2  Citrus flavanone naringin and its biological properties
			24.3.2.3  Citrus polymethoxylated flavones and their biological properties
		24.3.3  The biosynthesis of flavonoids in citrus fruits
	24.4  Ascorbic acid in citrus fruits
		24.4.1  The roles of ascorbic acid in human health
		24.4.2  The accumulation of AsA in citrus fruits
		24.4.3  The metabolism of AsA in citrus fruits
		24.4.4  The regulation of AsA in citrus fruits
	24.5  Conclusion
	References
Index
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