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Jinq-Tian Ling, N. Nito, and M. Iwamasa

Protoplasts were isolated from embryogenic calli of Citrus reticulata cv. Ponkan and Citropsis gabunensis, and fused in electric fields. The maximal fusion efficiency was obtained by application of AC at 75 V/cm (1.0 MHz) and DC square-wave pulse at 1.125 KV/cm for 40 usec. Fusion-treated protoplasts were cultured on MT medium without phytohormone, solidified with 0.6% agar. Colonies from the protoplasts were proliferated on MT medium with zeatin 1 mg/l and 0.9% agar. Selection of somatic hybrid callus was based on chromosome count and isoenzyme analysis. The somatic hybrids were tetraploid (2n=36). C. reticulata and C. gabunensis were both homozygous at Got-1 locus, but distinguishable easily because band of the latter migrated faster than that of the former. In zymogram of somatic hybrid, both parent bands were retained and a new hybrid band was also evident between them. Embryos from somatic-hybrid callus regenerated intact plant. The hybrid plants showed intermediate morphological characteristics of the parents.

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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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Ockert P.J. Stander, Jade North, Jan M. Van Niekerk, Tertia Van Wyk, Claire Love, and Martin J. Gilbert

This study aimed to determine the effects of different types of nonpermanent netting (NPN) on foliar spray deposition, insect pest prevalence, and production and fruit quality of ‘Nadorcott’ mandarin (Citrus reticulata) trees in a commercial orchard at Citrusdal (lat. 32 32′31″S, long. 19 0′42″E), Western Cape, South Africa. The deposition quantity (FPC%) of foliar spray volumes of 3500, 7000, or 15,000 L·ha−1 was greater for leaves of control trees compared with leaves treated with NPN during summer (January) (8.8 vs. 6.1; P = 0.0055) and winter (June) (4.8 vs. 3.1; P = 0.0035). Deposition uniformity (CV%) was better for control leaves during summer (64.9 vs. 75.2; P = 0.0062) and winter (59.6 vs. 80.5; P = 0.0014), and deposition quality (ICD%) was better during winter (79.4 vs. 84.2; P = 0.0393). There were no differences in FPC%, CV%, and ICD% for fruit when foliar spray volumes of 3500 and 15,000 L·ha−1 were used for the control and NPN treatment groups during winter. However, with a foliar spray volume of 7500 L·ha−1, fruit from the control treatment group had greater FPC% (19.3 vs. 6.1; P = 0.0262), CV% (70.3 vs. 50.9; P = 0.0484), and ICD% (57.1 vs. 79.9; P = 0.0157). There were no differences in macronutrient concentrations between the leaves of trees subjected to control and NPN treatments, but leaf zinc (<81%; P = 0.0317) and iron (<78%; P = 0.0041) concentrations were lower with the NPN treatment. During short NPN treatments, fruit yield was reduced by ≈37% compared with that after control treatment, and longer NPN treatments had no effect on fruit yield. The reduction in fruit yield with NPN was not related to the effects of NPN on foliar spray deposition or to lower leaf micronutrient concentrations. The lower fruit yield during short NPN treatments was most likely caused by fruit drop that was exacerbated by the removal of the NPN. In the long NPN treatment group, fruit damage caused by sunburn was reduced by 17%, but the outer canopy fruit experienced increased wind damage or scarring. Except for the lower titratable acidity content with the shortest NPN treatment and the higher Brix°:TA ratio with two NPN treatments, NPN did not impact other fruit quality attributes. The use of NPN excluded male wild false codling moths (Thaumatotibia leucotreta) (FCM) males; however, it was still possible to capture a very small amount of mass-released sterile FCM and wild fruit flies under the NPN.

Open access

H. K. Wutscher and A. V. Shull

Abstract

Twenty-nine mandarins (Citrus reticulata Blanco) and mandarin hybrids on sour orange (C. aurantium L.) rootstock were grown for 10 years. At the first 6 harvests, ‘Orlando’ tangelo was most productive, followed by ‘Pearl’, C52-36-6, 6-5-15, and ‘Fairchild’. Hybrids 6-12-26, C52-84-35, and ‘Minneola’ produced the largest fruit. About half the selections had small fruit (fruit circumference <22 cm); 16 selections lacked attractive exterior color. ‘Minneola’, ‘Orlando’, and ‘Page’ fruit contained more than 60% juice; only 5 selections had less than 50%. Total soluble solids were never below 10% and were usually 11% or higher. Four selections had acids below 0.70% and 6 were above 1.0%, with ‘Lee’ being lowest and C52-84-35 highest. All Brix acid ratios were above 9:1. Ten selections had 30 or more seeds/fruit; only 3 had 15 or less, including satsuma with 4 seeds/fruit. Very few of the selections appear promising under the South Texas environment.

Open access

Coral Ortiz, Antonio Torregrosa, Enrique Ortí, and Sebastià Balasch

trees grown on production systems trained to a narrow tree wall canopy. Some studies using manual gasoline-powered shakers and electric combs for thinning mandarins ( Citrus reticulata ) of the varieties Clemenrubí and Clemenules have been performed

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Ockert P.J. Stander, Karen I. Theron, and Paul J.R. Cronjé

. Chiarawipa, R. 2005 Fruit splitting occurrence of Shogun mandarin ( Citrus reticulata Blanco cv. Shogun) in southern Thailand and alleviation by calcium and boron sprays Songklanakarin J. Sci. Technol. 27 719 730 Stewart, W.S. Klotz, J.L. Hield, H.Z. 1951

Open access

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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Ockert P.J. Stander, Johané Botes, and Cornelius Krogscheepers

‘Ponkan’ ( Citrus reticulata Blanco) J. Jpn. Soc. Hort. Sci. 65 513 523 McArtney, S.J. Obermiller, J.D. 2012 Use of 1-aminocyclopropane carboxylic acid and metamitron for delayed thinning of apple fruit HortScience 47 1612 1616 McArtney, S.J. Obermiller

Open access

S.P. Monselise, E.E. Goldschmidt, A. Golomb, and R. Rolf

Abstract

Scaffold branches of ‘Michal’ tangerine (a Citrus reticulata hybrid) trees were fall-girdled once. Individual branches were driven into opposite phases of alternate bearing which continued for at least 3 successive years, without an additional stimulus. Bearing and nonbearing branches behaved like whole on- and off-trees, with regard to macronutrient and starch concentration in leaves and twigs, respectively. Off/on ratios for individual factors, however, were closer to unity than those previously found for whole alternating ‘Wilking’ trees, possibly due to the moderating effect of the common root system.