ArticlePDF Available

Improving Navel orange (Citrus sinensis L) productivity in Delta Region, Egypt



The objective of this work presents general information about the Washington Navel sweet orange cultivar (Citrus sinensis L.) productivity in Delta region, Egypt, over the next few years, focusing on increasing total yield and enhancement fruit quality by following good agricultural practices, and increasing alertness among growers of the need for implement fruit quality to compete in the global market. Some of the practices include using proper fertilizers, irrigation technique, pruning, integrated pest management and harvest technique.
Advances in Agriculture and Environmental Science: Open Access
Improving Navel orange (Citrus sinensis L) productivity
in Delta Region, Egypt
Waleed Abobatta
Agriculture Research Center, Egypt
Correspondence: Waleed Abobatta, Agriculture Research Center, 9 Gamaa, Egypt, Tel +201224296948, Email
Received: February 02, 2018 | Published: February 26, 2018
Copyright© 2018 Abobatta. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original author and source are credited.
Submit your Article |
Citation: Abobatta W. Improving Navel orange (Citrus sinensis L) productivity in Delta Region, Egypt. Adv Agr Environ
Sci. (2018);2(1): 8-10.
Citrus trees occupy a signicant economic importance among fruit
crops in Egypt regarding cultivated area, production and exportation
potentialities; also, it is the largest horticultural industry, Egypt
considered the largest orange exporter in the world and ranking as
the sixth largest producer. Orange is the main citrus species in Egypt,
where the area of cultivated about 133,236 hectares representing
about 69% of the total citrus area, producing about 2.9 million tons,
representing about 71% of the total citrus production, exports orange
about 1.1 million tons, representing about 92% of the total amount of
total citrus exports.1
Problem statement
There are different problems of navel orange productivity in the Delta
region like:
1. Poor irrigation technique mostly used excessive quantities of
water without a proper irrigation system.
2. Lack of appropriate amount of fertilizers, also, mostly there’s no
recommended fertilization programs
3. There are wide areas had low productivity due to the tree sinensis,
some of this orchards planting more than 50 years ago.
4. Low productivity of different orchards (around 22 tons/ ha).
5. Planting distance vary from 4x 6, 3x 5, 3x6 even 2x 3 in some
6. Most of the orchards in Delta region have mixed varieties within
the same eld.
7. Sour orange (Citrus aurantium L) considered the main rootstock
utilized in Delta region and mainly affected by soil pathogen like
Phytophthora root rot.
8. Local wholesaler and retailer prices are very low compared to
other fruits.
Cultivated area
Orange considered is the main cultivated species among citrus
varieties in Egypt, also, orange almost is planted in all of the Egyptian
governorates. However, most of the Navel orange planted area is
concentrated in the Delta governorates (Gharbia, Qalyoubia, Menoua,
Sharqiya, and Ismailia) which considered the main producing areas.
Navel oranges are the predominant variety of citrus all over Egypt and
especially in Delta region, also, Navel orange rank the rst position
between citrus crop and representing 60 percent of all cultivated area
and 60 percent of the total orange production.1
From another side, Navel orange is the most favorite cultivar in Egypt
and it is considered the popular fresh citrus fruits for the Egyptians
due to its seedless, large size and avor and aroma characteristic, fruit
high quality, desirable taste and low prices compared to other fruits,
Navel orange is the main source of early season income for citrus
growers in Delta region.
Egypt is one of the world’s leading orange producers and exporters
rank as the sixth orange producer in the world after Brazil, China,
USA, EU, and Mexico. Oranges represent around 30 percent of the
total Egyptian fruit production and 65 percent of citrus production.
Short communication
The objective of this work presents general information about the Washington Navel sweet orange cultivar (Citrus sinensis L.) productivity in Delta region,
Egypt, over the next few years, focusing on increasing total yield and enhancement fruit quality by following good agricultural practices, and increasing alertness
among growers of the need for implement fruit quality to compete in the global market. Some of the practices include usingproper fertilizers, irrigation technique,
pruning, integrated pest management and harvest technique.
Keywords: navel orange, citrus sinensis, yield, fruit quality, delta region.
Advances in Agriculture and Environmental Science: Open Access
Submit your Article |
Citation: Abobatta W. Improving Navel orange (Citrus sinensis L) productivity in Delta Region, Egypt. Adv Agr Environ
Sci. (2018);2(1): 8-10.
Orange cultivated area in 2016 reaches 133, 236 hectares producing
about 2.90 million tons, and Egypt’s proximity to major importing
Even though the deterioration of old farms in the various Delta
governorates for different reasons there are good chance for Egyptian
Navel orange growers to increase yielding and fruit quality due to
the availability of irrigation water, appropriate climatic conditions,
fertile soil, low labor costs, an early harvest time compared to other
producers in the world.
Orange verities
Several orange varieties are produced in Egypt but the main varieties
are six, Navel and Valencia are the major export varieties while the
others are used more for domestic consumption.
While, Navel orange considered the main variety produced in Delta
region, however, there are other varieties like Baladi Orange, Blood
orange, Khalily orange and Sweet Orange (Sukkari) but in small areas.
Implementation navel orange productivity in
delta region
Navel orange orchard management requires an understanding of
physiology and crop phenological stages, wherever appropriate
practice and enhancement of management activities improve the total
yields which increase the nal income for growers.
Nutrient management
In the Nile delta region, where water and fertile grounds are available
and just need good practice to manage nutrient applications like soil
testing, tissue testing to the determined amount of different fertilizers
according to trees requirements,2 also, preferable splitting nutrient
doses, and using proper application techniques
Nutrition management considered an important part of agricultural
performs that reduce pollution soil and groundwater resources, help
protect the environment and though, and keeping of different natural
resources. Proper nutrient management is essential to optimize yield
and productivity of navel orange, and reducing the environmental
Irrigation management
Most of the navel orange orchards in delta region irrigated by
ooding system which used excessive quantities of water, this system
and scheduling of irrigation require quickly change to improving
productivity through reducing water consumption and decrease the
loss of water and fertilizers.
Irrigation management practice could include the use of high-
efciency irrigation systems, proper tools like soil moisture sensors,
tensiometers, and weather data.
Pest management
Due to different reasons navel orange orchards infected with some
pests and diseases affects trees productivity, i.e. Citrus Leafminer,
Aphids, Asian Citrus Psyllids, various soft scales, Whiteies, fruit
ies, mealybugs, citrus thrips, citrus nematode, Phytophthora root rot,
stubborn disease.
The appropriate pest management practice working in two ways:
1. Preventative method: including choosing rootstocks fewer
susceptible to soil damage, removing weeds from orchards
to reduce sources of different pests, using a proper irrigation
system, development, and implementation of responsible farm
management practices that enable growth of a healthy root system,
2. Chemically control: the primary management strategy currently
depending on stimulating the proper handling of controlled using
biological control, newer and safer pesticides, rather than harmful
chemicals, and avoids Intensive chemical control.3
Integrated pest management could assist in reducing the pesticides
and different infections, also, reduction of probable hazards to labors,
consumers, and the environment through reduced fruit exposure.
Pruning management
Citrus trees have been pruned in different ways; some better than
others, with respect to the traditional technique, which only removes
dead, infected, weak wood, out of place branches.
Light is critically important for owering and fruit set in citrus trees
and considered the most critical factor controlling productivity of
trees, in unpruned trees, light intensity decreased inside the canopy
maybe 2% that of full sunlight which affects ower bud initiation,
owering, and fruit quality and tree growth.4
However, proper pruning and canopy management navel orange trees
effects in productivity of vegetative growth that increased total yield
and fruit quality.
The object of proper pruning is to encourage trees to produce a
balance of vegetative and fruiting wood, with efciently ventilated
interior citrus canopy and small enough to harvest from the ground
without the need for long rung ladder.
Fruit harvest
In delta region most of the citrus orchards harvesting manually for
many years, however, nowadays there’s increasing cost of harvesting
operations due to labor shortages (manual harvesting of citrus fruit
represents 35–45% approximately of total production cost), in the
same time manual harvesting offers the benets of determined fruit
selection and full product quality, but has a relatively low picking rate.
Picking technique need development by providing mechanical
harvesting methods to improve fruit quality and reduce harvesting
cost. Mechanical harvesting offers a considerably greater harvesting
rate over manual picking, the maximum picking rate of manual
pickers is 0.5 t/h, whereas the picking rate of trunk shaking harvesters
is 10 t/h.5
Weed control
Due to usage of ooding irrigation system, there are different kind
of weeds grow in citrus orchards in Delta region, mechanically
control for weeds used after harvesting to reduce compete with the
tree, and preparing rings manually around trees to avoid root damage
and infection with root rot disease and other pathogens and regular
removing before weed owering to prevent seeds production.
Advances in Agriculture and Environmental Science: Open Access
Submit your Article |
Citation: Abobatta W. Improving Navel orange (Citrus sinensis L) productivity in Delta Region, Egypt. Adv Agr Environ
Sci. (2018);2(1): 8-10.
Preferable usage handy mowing for weeds after fruit set to reduce
weed compete, during July weed could chopping again, to avoid
different kinds of the grasshopper, also, some growers spray herbicide
in the inter-rows escaping touching the plants, wherever, in other
areas farmers’ usage mulching materials to control weeds.
Short plan for improving navel orange productivity
in delta region
1. Using some agricultural bio stimulants substances including,
soil organic residues (humates compounds), yeast, and living
2. Application of plant growth substances provides important
economic benets to citrus farmers dependent on the time of
application and concentration.
3. Pruning: citrus tree needs full sun and light penetration all the
year to get determined crops, so annual pruning open canopy for
light and avoid crowding and shading.
4. The suitable quantity of irrigation water improves fruit quality
and increase total yield.
5. Balanced fertilizing program formulated to deliver exact nutrient
requirements for growth, predictable yield and fruit quality
Improving Navel orange orchards productivity and fruit quality in
Delta region depending on usage ofproper agricultural management
practice like balanced nutrition, proper irrigation system; right
pruning technique, using agricultural bio-stimulants, and integrated
pest management.
1. Annual Reports of Statistical Institute and Agricultural Economic Research
in Egypt. 2016.
2. Srivastava AK. Advances in Citrus Nutrition. 2012;369‒389.
6. Grafton-Cardwell, Elizabeth E, Stelinski LL, et al. Biology and
Management of Asian Citrus Psyllid, Vector of the Huanglongbing
Pathogens. Annu Rev Entomol. 2013;58:413–432.
7. Fischler M, Goldschmidt EE, Monselise SP. Leaf area and fruit size on
girdled grapefruit branches. J Amer Soc Hort Sci. 1983;108(2):218‒221.
8. Sanders KF. Orange harvesting systems review. Bio-systems Engineering.
2005;90 (2): 115–125.
9. Abobatta W. Growth and Fruiting of Valencia orange trees. LAP LAMBERT
Academic Publishing. 2015.
10. Zekri M. Factors affecting citrus production and quality. Citrus Industry.
... Pruning aims to optimize the radiation received by the plant, in addition to optimizing branch growth, so there are production pruning and maintenance pruning. Radiation is essential in citrus growth and production, especially for flower initiation, blooming, and fruit formation (Abobatta, 2018). Pruning branches make the plant canopy broader and more regular so that every part of the plant gets optimal light intensity. ...
Full-text available
Self-pruning can lower production costs, especially in the case of annual crops such as citrus. The study aimed to determine self-pruning of lime treated with growth regulators and a fertilizer. Self-pruning was applied on a one-year-old of Citrus aurantifolia from February 2020 to April 2022 in Bogor, Indonesia. The treatments used NPK at three levels: 22.5:7.5:2.5 g/tree, 32.5:17.5:12.5 g/tree, and 42.5:27.5:22.5 g/tree, and growth regulators: 500 ppm ichiphon + 100 µM ABA, 750 ppm ichiphon + 50 µM ABA, and 1000 ppm ichiphon. Initial symptoms of self-pruning, namely leaf fall, which correlated with the ethylene concentration in the leaves, occurred in all treatment applications. The combination of the NPK fertilizer 32.5:17.5:12.5 g/tree with 750 ppm ichiphon + 50 M ABA gave the highest ethylene concentration. The highest concentration of ABA was found on the first day after the treatment with the NPK fertilizer 42.5: 27:5: 22.5 g/tree and growth regulators 500 ppm ichiphon + 100 M ABA; however, it did not differ from the treatment with the NPK fertilizer 42.5: 27.5:22.5 g/tree and the 1000 ppm ichiphon growth regulator on the fourth and twelfth days. The percentage of secondary, tertiary, and deciduous branches did not differ between the treatments. Self-pruning that occurs as a result of induction by ichiphon, abscisic acid, and NPK fertilizers, can be an alternative to mechanical pruning.
... According to Abobatta (2018), fertilization is a cultivation technique used to improve soil nutrient availability in order to maximize yield. Fertilization will directly affect the growth, fruit-set, retention yield and quality improvement and sustainable production of Kinnow orchards (Huang et al., 2014;Yasseen and Manzoor, 2010). ...
Full-text available
Pruning and fertilization are factors that can determine the production and quality of citrus. The objective of this study was to determine the effect of pruning intensity and fertilizer doses of N (nitrogen), P (phosporus), and K (potassium) on citrus production and quality. The study was carried out in a citrus orchard in Central Java, Indonesia, over the course of two seasons, 2016-17 and 2017-18. The experiment was conducted as a two-factorial, completely randomized block design where the first factor was pruning intensity, namely 0, 5, 10, and 15 % of the total number of branches per tree while the second factor was doses of N, P, and K fertilizers, namely 0, 2, and 4 % of the weight of harvested citrus fruit in the previous season. The result showed that increasing doses of N, P, K fertilizers from 0 to 4 % increased fruit-set, harvested fruits, fruit size, content of vitamin C, sugar, and soluble solid. The highest fruit-set, weight of harvested fruits, and content of vitamin C were achieved by pruning intensity of 10 %.
... Table 2 shows that these areas reached about 144 thousand feddans, which increased from 122 to 158 thousand feddans with a significant annual growth rate of approximately 1.6%. According to[7] [8], the navel orange ranks first among citrus crops because it is considered as the most popular fresh citrus fruit for ...
Full-text available
In Egypt, oranges are the most important citrus crops for local consumptionor export. It represents approximately 72.2% of the total Egyptian citrus pro-duction in 2019/2020. The main cultivated variety of orange is the Washing-ton navel orange and it is more popular because of its delicious taste, nutri-tion, and its seedless besides being rich in vitamin C. Washington navelorange is susceptible to fruit cracking, and it is a common physiological dis-order that takes place during fruit development. This work aims to investigatethe negative effect of fruit cracking in reducing the yield and quality ofWashington navel orange produced in Egypt by studying major economic in-dicators and estimating an economical evaluation of using treatment ofWashington navel orange during the period time of 2007/2008 until2019/2020. Results showed that fruit areas and production of Washingtonnavel orange represented about 52.9% and 53.2% of fruit areas and produc-tion of orange during the study period. However, the yield was unstable witha significant annual growth rate of about 1.1%. Also, the last mentionedtreatment achieved a high price for farmers by about 5.1% and total revenueof about 3.2% during the study period. Nowadays, Egypt has become thelargest exporter of oranges in the world within the last year and the achievedearnings reached $661 million in 2019/2020. In addition, results showed thatevaluation of using a treatment to reduce the rate of Washington navelorange cracking was economical to be applied.
... Egypt is one of the world's largest orange growers, with exports ranking sixth globally. Oranges account for around 30% of overall Egyptian fruit output and 65% of citrus production [18]. Because orange trees must be trimmed annually, substantial amounts of waste are generated, causing several environmental problems. ...
In this paper, composites of PEO/PVP reinforced with different biochar loadings (0, 0.5,1, and 2 wt %) were obtained via the solution casting method. The crystallite size of the blend is increased by increasing the biochar up to 1 wt%. This behaviour is due to the increasing intermolecular interaction between biochar and blend. The strong interaction between C-O/C-O-C of blend and biochar caused altering the crystalline regions deduced from FTIR. The optical properties of the composite are dependent on the biochar content, where the direct and indirect optical band gaps are decreased upon the addition of the biochar up to 1 wt%. The refractive index values at 650 nm increased by increasing biochar concentration in PEO/PVP blend. Urbach tail energy is increased by adding biochar to 1 wt%. This behaviour is because increasing traps in the blend result in a lower energy transition. The effect of different concentrations of the biochar on the blends' optical parameters such as optical conductivity, optical dielectric constant, and extinction coefficient is also studied. The thermal stability of the blend increased with increasing biochar content up to 1 wt% due to an increased degree of crystallinity. Further addition of biochar reduced the thermal stability of the blend due to aggregation of biochar particles.
... Citrus represents an important economic Egyptian fruit crop. Egypt ranks the 6th largest orange exporter and producer worldwide [6]. In 2019/2020, Foreign Agriculture Service (FAS) Cairo forecasts fresh orange exports to reach 1.5MMT. ...
Full-text available
Aging of the skin is a complicated bioprocess that is affected by constant exposure to ultraviolet irradiation. The application of herbal-based anti-aging creams is still the best choice for treatment. In the present study, Citrus sinensis L. fruit peels ethanolic extract (CSPE) was formulated into lipid nanoparticles (LNPs) anti-aging cream. Eight different formulations of CSEP-LNPs were prepared and optimized using 2 3 full factorial designs. In vivo antiaging effect of the best formula was tested in Swiss albino mice where photo-aging was induced by exposure to UV radiation. HPLC-QToF-MS/MS metabolic profiling of CSPE led to the identification of twenty-nine me-tabolites. CSPE was standardized to a hesperidin content of 15.53 ± 0.152 mg% using RP-HPLC. It was suggested that the optimized formulation (F7) had (245 nm) particle size, (91.065%) EE, and (91.385%) occlusive effect with a spherical and smooth surface. The visible appearance of UV-induced photoaging in mice was significantly improved after topical application on CSPE-NLC cream for 5 weeks, levels of collagen and SOD were significantly increased in CSPE-NLC group, while levels of PGE2, COX2, JNK, MDA, and elastin was reduced. Finally, The prepared anti-aging CSPE-NLC cream represents a safe, convenient, and promising skincare cosmetic product.
... Majority of Navel orchards are cultivated in Delta region due to proper soil, freshwater, and climate, whereas, there are many neglected orchards cultivated for 50 years approximately with improper pruning practice, some of these orchards need ladders to collect fruits during the harvesting season [2]. Proper management of various activities such as pruning, fertilizing, irrigation, and pest control, in proper timing, enhance physiological functions and resulting in high production with worthy fruit quality [3]. Wrong pruning practice affect negatively tree yield and fruit quality, also, increase spreading pathogens. ...
Full-text available
Citrus ranking as the first fruit crop in Egypt, Navel orange (citrus sinensis L.) represents the main citrus variety cultivated in Egypt in both terms of cultivated areas or productivity, currently; there are different challenges faces navel orange production which required proper management for various agriculture practices. Canopy management is a very important practice in determining tree productivity, there is more attention to construct strong tree structure and sustain regular productivity, and there are different mistakes in Navel orange orchards particularly the old one like higher trees and complicated canopy which affect tree growth and productivity. The aim of pruning variable from new orchards to mature one, also, there are different types of pruning include Regular annual pruning, suckering, skirting up pruning, control of alternate bearing, canopy thinning, and Rejuvenation of old orchards. There are various factors that determine the proper type of pruning and the accurate tools used in pruning like orchard conditions, trees size, and varieties growth habitat
Full-text available
The goal of this study was to examine how to improve the vegetative growth, nutritional status, productivity, and fruit quality of Washington navel orange trees by examining the effect of foliar application of ZnSO4 (0, 300, and 600 mg/L) solutions in combination with CuSO4 (0, 200, and 400 mg/L) solutions on Washington navel orange trees, which were 11 years old and grown in clay loam soil with a surface irrigation system. The results showed that all the investigated measurements responded specifically to each investigated factor. ZnSO4 elicited a stronger and more effective response than CuSO4. Nonetheless, the response varied only slightly or moderately from one measurement to the next. In terms of the interaction effect between ZnSO4 and CuSO4 concentrations, the effect of each investigated factor was directly reflected in its combinations, with ZnSO4 (600 mg/L) and CuSO4 (200 and 400 mg/L) being the most effective for the majority of the measurements under consideration. When the highest level of ZnSO4 was combined with the highest level of CuSO4, the highest values for the various vegetative growth parameters shoot length and diameter, number of leaves per shoot, leaf area, and total assimilation area per shoot were obtained. As a result, the nutritional status (the highest total leaf chlorophyll and leaf mineral contents) was significantly coupled with the treatment of 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4. Moreover, the combinations of the highest ZnSO4 concentration (600 mg/L) and CuSO4 concentration (400 mg/L) exhibited the greatest statistical values of the measurements of fruiting aspects as well as fruit quality. Consequently, it can be recommended that using 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4 as a foliar spray on monthly basis during the period from March to July could be safely recommended under similar environmental conditions and horticulture practices adopted in the present experiment.
Full-text available
A survey of insects infesting citrus orchards was conducted in Menoufia governorate at three localities during 2019. The most common insects were, cottony cushion scale, Icerya purchase, seychelles scale, Icerya seychellarum, comma scale, Lepidosaphes beckii, citrus black scale, Chrysomphalus aonidum, and red scale, Aonidiella aurantii. The obtained results revealed no infestation was recorded along with July and August of Icerya (Mealybugs) insects. However, there were two peaks recorded in May and November, as well as the highest averages were recorded in Tala center while the lowest were recorded in Alshohadaa center, moreover Shebin Elkom center occupied intermediate status between the two centers. There were no mealybugs insects during July and August, but the highest average numbers were recorded in May. Tala center orchard has the highest population of tested insects on Naval Orange along with the experiment. There were no Chrysomphalus aonidum insects at Shebin Elkom and Alshohadaa of Balady mandarin orchards during year months. Tala and Shebin Elkom orchards have similar numbers but Alshohadaa has smaller averages. Shebin Elkom orchard has the highest infection with Lepidosaphes beckii, and Aonidiella aurantia, while Alshohadaa has the least numbers. It could be recommended that control of these pests must be done along with June, July, and August, where the least population of insects.
Full-text available
The objective of this study was to add more information about the effect of different Magnetite and K-Humate treatments on vegetative growth, leaf mineral content, yield and fruit quality of the Valencia orange trees. The results showed that Magnetite and K-Humate positively affect on growth parameters, leaf chemical composition, total yield, yield efficiency and fruit quality. Wherever, M3H2 treatment was superior in increasing vegetative growth and total yield in both seasons. Generally; Magnetite and k-Humate have been utilized to reduce the effect of soil and water salinity on plant growth and enhancement different growth parameters, also, reduced negative effects of B, Na and Cl elements on trees performance.
Full-text available
The dependence of fruit growth of grapefruit ( Citrus paradisi Macf.) upon leaf area was investigated on girdled branches by manipulating leaf and fruit numbers. Leaf areas of 2.0 ± 0.5 m ² per fruit were found to be saturating with regard to fruit growth rate and size. Fruit on internal, shaded branches required larger leaf areas. Fruit on girdled branches weighed 44 to 119% more than fruit in ungirdled branches, which had leaf areas of 0.35 to 0.55 m ² per fruit. This indicates that leaf area is one of the factors limiting fruit growth. Starch accumulated in thin twigs during the fruit growth season, forming a saturation curve similar to those obtained for fruit size when plotted against leaf area per fruit. Increasing leaf area per fruit could involve a decrease in photosynthetic activity, a possibility which now is being investigated further.
Full-text available
A guesstimate proclaims over 900 million people in the world are undernourished, and malnutrition alone is responsible for 3.5 million deaths annually. Plant nutri-tion is a complex process that has developed over the course of plant evolution with the discovery of fundamental importance of plant nutrition, only second to the discovery of photosynthesis as an effective via-medium to bolden plant de-fence mechanism (Chapter 1). The accumulated biochemical and molecular evi-dences have incredibly confirmed that the nutrient stress is invariably associated with changes in antioxidant system (Chapter 2). Under such nutrient-induced stresses, phytophenolic nutrients are first to be affected (Chapter 3). Later, with the universal acceptability to the concept of essentiality of nutrients by Aron and Stout, the investigations on the anatomical, histological, and biochemical nutri-tional disorders became distinctly understandable through a variety of diagnos-tics. For such regulatory systems to function, nutrient conditions need to be sensed, signals need to be transduced, gene expression need to be transcriptionally and post-transcriptionally regulated, transporters be properly trafficked through endomembrane system, and cell cycles need to be coordinated. Such a wide range of responses may be a reflection of the very sophisticated systems that have evolved in plants over time. Citrus fruits are produced in many countries around the world, although pro-duction shows geographical concentration in certain areas, but still citrus fruits rank first in international fruit trade in terms of value, evolving from a producer- driven to a more consumer oriented market. In the backdrop of demography–driven diminishing per capita availability of arable land, plant nutrition has gained phenomenal significance in meeting the challenge of sustaining productivi-ty over changing resource outputs. Indeed, from soil and plant diagnosis to sug-gestions for appropriate fertilizer applications (Chapter 4), current levels of citrus production would never have been possible without the knowledge of plant nutri-tion. A definite credit in this context could be accredited to developments in ana-lytical techniques in both leaf (Chapter 5 and 6) and juice (Chapter 7) analysis. Of late, trunk nutrition gained some momentum (Chapter 8) where conventional methods of nutrient supply have not been able to put forth the desired results spaced over time. In addition, proximal sensing of nutrient stress (Chapter 9 and 10) and spectrum of soil enzymes as dictum of soil fertility changes (Chapter 11) have further provided some authoritative progress towards precise diagnosis of nutrient stresses. Such breakthroughs will go a long way in developing early warning system in the years to come to enable the redressal to genesis of any nutritional disorder within current growth cycle of crop. Occurrence of nutrient constraints is as old as history of citrus cultivation. Any nutrient constraint at various crop phenophases on nutrient deprived soils has al-ways baffled citrus nutritionists that could well jeopardize the incentives accruing through otherwise balanced fertilization in highly diversified nutrient demanding citrus cultivars. The current state of knowledge on the subject is very fragmenta-ry. The subject becomes still very complex in the absence of knowledge on kinet-ics and co-kinetics of different nutrients being partitioned across different growth stages so that growth stagewise nutrient demand is precisely modulated. Accor-dingly, type and source of nutrients are fed synchronising with physiological nu-trient demand (Chapter 12). Two major processes of nutrient cycling viz., minera-lization and immobilization of nutrients via litter fall offers a lion’s share in meeting out the crop nutrient demand in perennial canopy framework of citrus. Development of microbial consortium (microbial reactor) exploiting the native and natural microbial synergisms (with twin role as growth promoter and antago-nistic against soil borne pathogens) is one of the popular methods of providing the desired dynamism to nutrient dynamics within the rhizosphere (Chapter 13). Such rhizosphere specific consortia could further engineer rhizosphere’s nutrient de-mand and supply through loading with organic manures in much value added form, e.g., biodynamic soil fertility management (Chapter 14). The efforts such as these, could only meet their objectivity unless duly supported by methods leading to improved nutrient use efficiency (Chapter 15 and 16) including the intervention of genomics with metaloenzymes (Chapter 17) and variable rate fertilization (Chapter 18). Development of nutrient norms using crop specific plant parts in citrus culti-vars, needs a thorough revisit and to be field validated in order to provide their wider application down to orchard level. However, the major point of discon-tent still remains to be warded off with respect to whether nor not different nu-trient norms are required as per cultivar within the same variety. The biggest con-straint on the other hand in making soil test ratings more purposeful is the non-redressal of spatial variation in soil fertility. Conjoint use of geoinformatics (Geo-graphical Information System, Global Positioning System and Remote Sensing) with nutriomics, site specific nutrient management strategy, fertigation (Chapter 19) comparatively new concept of open field hydroponics (Chapter 20), and ex-ploiting nutrient–harmone synergy (Chapter 21) have collectively yielded definite edge over conventional methods of nutrient management. Ironically, one of the most profoundly researched nutritional disorder, popularly known as lime –induced iron deficiency still needs multi-pronged strategy with regard to manage-ment of citrus on calcareous soils (Chapter 22). Well known mycorryizal depen-dency of citrus still remains an unexploited issue (Chapter 23). The concepts such as organic soil fertility management (Chapter 24) and integrated nutrient management utilising collective efficacy of organic manures, inorganic fertilizers, and microbial diversity (Chapter 25) have taken this important issue a step for-ward towards sustainable nutrient management. Such approaches have given birth to a concept like best management practices (Chapter 26) duly validated through economic analysis (Chapter 27). The entire gamut of citrus nutrition remains an unfinished exercise unless dealt with the issues like assessing soil salinity (Chapter 28) and aluminium toxicity (Chapter 29) on soluble salt rich (high pH) and divalent bases deprived (low pH) soils, respectively, considering the extreme sensitivity of citrus under both the soil conditions. Despite all these concerns, application of sensor-based technology has further added a new dimension in estimating the fruit yield (Chapter 30) in an authentic manner so that sustainable productivity vis-à-vis nutrient management strategies go hand-in-hand in offering an alternative source of nutritional security in an era of soils sick of multiple nutrient deficiencies taking their severe toll on human nutrition. This is probably a maiden effort to consolidate the information related to dif-ferent aspects of citrus nutrition in such a holistic manner. I am indebted to my colleagues numbering as many as 71 (all of them are highly respected for their ex-cellent contribution) well represented by as many as 19 frontline citrus growing countries. This has been a truly an educative experience while the course of this book. I am sure, the book will serve as a novel source of information for the stu-dents, teachers and researchers as well.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the most important pest of citrus worldwide because it serves as a vector of "Candidatus Liberibacter" species (Alphaproteobacteria) that cause huanglongbing (citrus greening disease). All commercially cultivated citrus is susceptible and varieties tolerant to disease expression are not yet available. Onset of disease occurs following a long latent period after inoculation, and thus the pathogen can spread widely prior to detection. Detection of the pathogen in Brazil in 2004 and Florida in 2005 catalyzed a significant increase in research on D. citri biology. Chemical control is the primary management strategy currently employed, but recently documented decreases in susceptibility of D. citri to several insecticides illustrate the need for more sustainable tools. Herein, we discuss recent advances in the understanding of D. citri biology and behavior, pathogen transmission biology, biological control, and chemical control with respect to "Candidatus Liberibacter asiaticus." Our goal is to point toward integrated and biologically relevant management of this pathosystem.
The harvesting of citrus fruit represents 35–45% of total production cost. Hence, an improvement in the efficiency of this one operation has a significant effect upon enterprise viability and profitability. The traditional manual harvesting method is very labour intensive, and thus expensive.Mechanical harvesting methods have been widely researched and significantly improved. This is illustrated by the large amount of research data available and reviewed in this paper. The performances of the air shaking, trunk shaking, limb shaking and canopy shaking mechanical harvesting systems are briefly summarised. The results of several tree shaping and orchard layout studies have been included because the operating environment of the mechanical harvester affects its performance. The research results show that maximum harvester performance and maximum orchard productivity are not necessarily mutually exclusive, the correct choices of harvesting system and orchard layout can optimise both aspects.Quality fruit selection is very desirable because it achieves the maximum fruit price through the supply of the highest-quality fruit. This review has found that none of the mechanical systems investigated have matched the high-quality selection ability of manual pickers. Hence, this review also includes the results of research into alternative methods of maximising manual picker productivity in order to minimise the cost of manual picking.
Factors affecting citrus production and quality. Citrus Industry
  • M Zekri
Zekri M. Factors affecting citrus production and quality. Citrus Industry. 2011.