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Samuel Kwakye, Davie M. Kadyampakeni, Kelly Morgan, Tripti Vashisth, and Alan Wright

needs to be applied to HLB-affected [‘Bingo’ ( Citrus reticulata, Blanco)] trees in Florida, considering its role in photosynthesis and biological defense of the citrus tree. There has been little to no research of the response of citrus mandarins to

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S. Singh, B.K. Ray, S. Bhattacharyya, and P.C. Deka

Multiple shoots were obtained from shoot tips (2 to 3 mm) derived from mature plants (5 to 6 years old) of Citrus reticulata Blanco cv. Khasi mandarin and C. limon Burm.f. cv. Assam lemon when cultured on Murashige and Skoog (MS) medium, supplemented with (mg·liter-1) 1.0 BAP, 0.5 kinetin, and 0.5 NAA. Root induction was observed when 7-week-old single shoots (≈ 2 cm long) of both Citrus species were cultured on MS medium supplemented with (mg·liter-1) 0.25 BAP, 0.5 NAA, and 0.5 IBA. These plantlets were successfully established in the soil. Chemical names used: naphthalene acetic acid (NAA), indole 3-butyric acid (IBA), and benzylamino purine (BAP).

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Mebelo Mataa and Shigeto Tominaga

The effects of root restriction, induced by root restriction bags, was evaluated on `Yoshida' Ponkan mandarin (Citrus reticulata Blanco). Trees were planted in 0.02-m3 volume root wrap bags (RWBs), which were made from woven polystyrene fiber, or root control bags (RCBs) made from nonwoven UV-stabilized Duon polystyrene fibre with plastic bottoms. A direct soil planted, nonrestricted root treatment (DPC) was included as a control. After 3 years, reductions in height (14% to 29%), canopy volume (66% to 43%), girth (10% to 22%), and leaf area (8% to 12%) were recorded in both of the root restriction treatments. Greater reductions occurred in the RWB treatment. Photosynthesis, transpiration, water potential, and leaf carbohydrate content were not affected by root restriction although soil moisture content was lower in the root restricted treatments. Fruiting efficiency (i.e., number of fruit per unit volume of tree canopy) improved only in the RWB treatment over the control. Total soluble solids and the fruit color index were enhanced by root restriction.

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José Egea, Manuel Rubio, José A. Campoy, Federico Dicenta, Encarna Ortega, María D. Nortes, Pedro Martínez-Gómez, Antonio Molina, Antonio Molina Jr, and David Ruiz

‘Mirlo Blanco’, ‘Mirlo Anaranjado’, and ‘Mirlo Rojo’ are very early-season ripening apricot cultivars ( Prunus armeniaca L.) with high productivity, excellent fruit quality, and an attractive red-blushed fruit for fresh markets. These cultivars are

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Ute Albrecht and Kim D. Bowman

Huanglongbing (HLB) is a destructive disease of citrus in most citrus-producing countries worldwide. The disease, presumably caused by phloem-limited bacteria of the genus Candidatus Liberibacter, affects all known citrus species and citrus relatives with little known resistance. Typical disease symptoms are the production of abnormal-looking fruit and chlorosis or blotchy mottle of the leaves followed at advanced stages by tree decline and death. Trifoliate orange (P. trifoliata L. Raf.) and some of its hybrids reportedly lack distinct disease symptoms despite infection with the pathogen. US-897 is a hybrid of trifoliate orange and ‘Cleopatra’ mandarin (C. reticulata Blanco), the latter being highly susceptible to HLB. This study investigated whether field-grown, naturally infected trees and greenhouse-grown, graft-inoculated seedlings of this genotype display tolerance or resistance to HLB. It was shown that naturally infected US-897 trees exhibited no distinct disease symptoms commonly associated with HLB, except for the occurrence of few mottled leaves in a small percentage of trees. Analysis of fruit and seed from infected trees did not detect any growth reduction or otherwise negative impact on development. Graft-inoculated US-897 seedlings became polymerase chain reaction (PCR)-positive for the pathogen but exhibited a superior performance compared with ‘Cleopatra’ mandarin seedlings, which displayed severe disease symptoms soon after inoculation. Despite infection, most US-897 seedlings did not develop leaf symptoms typical for HLB. Foliar symptoms observed in a small number of plants at later stages of the disease were faint and difficult to discern. Contrary to ‘Cleopatra’ seedlings, growth in stem diameter was only moderately reduced or unaffected in infected US-897 seedlings. The superior performance of US-897 plants in greenhouse and field locations suggest tolerance of this genotype to Ca. L. asiaticus.

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Andrew J. Krajewski and Etienne Rabe

To investigate the effects of bud age on sprouting and flowering, bearing Clementine mandarin trees were hand-pruned at monthly intervals from late spring to fall. This pruning resulted in regrowth bearing axillary buds ranging in age from 9 to 5 months. After winter rest and during the return bloom, sprouting and flowering were assessed on axils on terminally positioned stems of these ages. The proportion of axillary buds sprouting and the number of spring shoots produced by each sprouting axillary site decreased with decreasing bud age. The proportion of axils sprouting one or more inflorescences, and the average number of flowers per stem also decreased with decreasing bud age. The number of axillary sites per stem, also significantly affected sprouting and flowering. Our results demonstrate the potential of hand-pruning to manipulate sprouting and return bloom depending on when in the summer or autumn the trees are pruned.

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Emilio Nicolás, Trinitario Ferrandez, José Salvador Rubio, Juan José Alarcón, and Ma Jesús Sánchez-Blanco

( Clary et al., 2004 ; Franco et al., 2000 ; Sánchez-Blanco et al., 1998 , 2004a , 2004b ; Savé et al., 1993 ). Although studies in relation to cultivation techniques in R. officinalis have been realized ( Silva and Pedras, 1999 ), the agronomic and

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Francisco Javier López-Escudero, Miguel Ángel Blanco-López, Carmen Del Río Rincón, and Juan Manuel Caballero Reig

Verticillium wilt of olive (VWO), incited by Verticillium dahliae Kleb., has become the most destructive disease of olive throughout the Mediterranean basin ( Al-Ahamad and Mosli, 1993 ; Blanco-López et al., 1984 ; Hiemstra and Harris, 1998

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Jesús A. Gil-Ribes, Louise Ferguson, Sergio Castro-Garcia, and Gregorio L. Blanco-Rodán

machine together, and for determining energy efficiency. Analyzing the process of the detachment and the fruit harvesting enabled us to make specific recommendations for harvester operation, shaking time ( Blanco-Roldán et al., 2009 ), and vibration

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Sabrina J. Ruis, Humberto Blanco-Canqui, Ellen T. Paparozzi, and Russ Zeeck

United States ( USDA-NASS, 2017 ). A fraction (30% to 50%) of the residue produced could be sustainably removed for expanded uses ( Blanco-Canqui and Lal, 2009 ; Graham et al., 2007 ; Zhao et al., 2015 ). This means ≈92.5 to 185 Mg can be available for