Oleocellosis Injury of Fruitlets from Late-season Mechanical Harvesting of ‘Valencia’ Orange Trees after Different Irrigation Treatments Does Not Affect Internal Fruit Quality

Oleocellosis or oil spotting on the peel of citrus fruit is a common post-harvest injury caused by improper handling. Mechanical injury allows phytotoxic oil to leak out of oil glands and cause injury to surrounding flavedo cells, resulting in oleocellosis. Mechanical harvesting (MH) of ‘Valencia’ sweet orange is conducted in late spring, when the next season's fruitlets are in their early stages of development. There is a concern that mechanical injury from harvesting machines can cause oleocellosis and fruit drop of young, green ‘Valencia’ sweet orange fruitlets, especially late in the harvest season when fruitlets are relatively large. We evaluated the effects of winter drought stress and subsequent late-season MH with a canopy shaker on oleocellosis of ‘Valencia’ sweet orange fruitlets. In April, mature fruit size, juice content, total soluble solids, and acidity were unaffected by previous winter drought stress treatments. Mechanical harvesting removed ≈90% to 95% of mature fruit and 20% to 50% of fruitlets depending on previous drought stress treatments and harvesting date. Beginning 1 week after the late harvest (13 June), attached fruitlets were tagged and visually evaluated approximately every other month to determine oleocellosis injury until the late-season harvest 12 months later. Only 12% of the fruitlets had oleocellosis on more than 30% of their surface area. Up to 75% of the fruitlets from the previously drought-stressed trees had less than 10% of their surface area injured after MH and 11% of these fruitlets dropped before harvest. Nonetheless, there was no significant increase in fruit drop with increased surface area injured nor was juice quality affected at harvest. Overall, fruit surface oleocellosis decreased and healed as fruit expanded, but surface blemishes did not completely disappear. Thus, fruitlet oleocellosis in late-season mechanically harvested trees was cosmetic and did not increase fruit drop nor alter internal fruit quality.

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Young-tree Performance of Juvenile Sweet Orange Scions on Swingle Citrumelo Rootstock

HortScience ◽

10.21273/hortsci.46.4.541 ◽

2011 ◽

Vol 46 (4) ◽

pp. 541-552 ◽

Cited By ~ 8

Author(s):

William S. Castle ◽

James C. Baldwin

Keyword(s):

Sweet Orange ◽

Early Spring ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Juice Quality ◽

Cumulative Yield ◽

Young Tree ◽

Late Season ◽

Swingle Citrumelo ◽

Blood Orange

A worldwide search was conducted for sweet orange [Citrus sinensis (L.) Osb.] selections with higher yield and better juice quality than existing commercial cultivars used in Florida primarily by the processing industry. Seeds of nearly 100 selections were introduced, germinated, and used as a source of buds for propagation. The scion selections were divided among six trials established by propagating juvenile buds from ≈12-month-old scion seedlings onto Swingle citrumelo [C. paradisi Macf. × Poncirus trifoliata (L.) Raf.] rootstock plants already in place in the field. Comparison trees using buds from mature sources were produced in a commercial nursery. The trials consisted of four to five replications of one- or two-tree plots with trees planted 4.3 × 6.7 m within and between rows, respectively. The scions were early-maturing (fall to early winter), midseason (winter to early spring), and late-season (early spring to early summer) common orange, blood orange, and ‘Pera’ orange selections. Data collected routinely included seed counts, standard measurements of juice quality, and yield during an ≈13-year period of evaluation. All trees exhibited typical juvenile traits such as vigor and thorniness; however, flowering and first cropping were not substantially delayed. Many selections began fruiting within 3 years after planting, which is the common commercial experience among trees propagated with mature bud sources. Many selections were low-seeded with counts of less than 10/fruit. Mean cumulative yield (8 years) among the early- and midseason selections in the first-planted trial was 1390 kg/tree and ranged to a high of 1751 kg/tree; for the late-season types, the mean was 947 kg/tree with little variability among eight selections. The yields of the early- to late-season selections in the other trials were similar. The blood orange selections proved to be mostly midseason in maturity. They lacked the deep peel and flesh coloration of blood oranges grown in a Mediterranean-type climate, but some selections did develop an enhanced orange color of the juice and the different flavor typical of blood oranges. ‘Pera’ orange selections exhibited a bud union incompatibility and subsequent decline with Swingle citrumelo rootstock and also when another sweet orange was inserted as an interstock. Their mean cumulative yield over six seasons was 797 kg/tree with an ≈30% difference between the lowest and highest values. Juice soluble solids, acid, and color values were typical of ‘Pera’ fruit grown in Brazil. The overall collection of sweet oranges displayed considerable diversity in their traits despite their supposed origin as a monophyletic group. Several early-season selections were released for commercialization, including ‘Earlygold’ and ‘Itaborai’, because of their better juice color and flavor. ‘Vernia’, a midseason selection, was released because of its high juice quality in late winter–early spring and its cropping precocity.

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Peach Fruit Quality Is Affected by Shade during Final Swell of Fruit Growth

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.116.3.383 ◽

1991 ◽

Vol 116 (3) ◽

pp. 383-389 ◽

Cited By ~ 49

Author(s):

Richard P. Marini ◽

Donald Sowers ◽

Michele Choma Marini

Keyword(s):

Fruit Quality ◽

Prunus Persica ◽

Fruit Weight ◽

Soluble Solids ◽

Photon Flux ◽

Fruit Drop ◽

Red Color ◽

Solids Content ◽

Fruit Harvest ◽

The Relationship

Girdled or nongirdled `Biscoe' peach (Prunus persica [L.] Batsch) secondary scaffold branches were covered with shade fabric to provide a range of photosynthetic photon flux densities (PPFD) from 44 to 20 days before harvest (DBH), from 20 to 0 DBH or 44 to 0 DBH. Fruit quality was affected differently by the various periods of shade during the final swell of fruit development. Shading 40 to 20 DBH did not affect fruit weight or quality, whereas shading 44 to 0 DBH had the greatest effect on fruit weight and quality. Fruit quality was generally similar on branches exposed to 100% and 45% incident PPFD (IPPFD). Fruit on” girdled branches generally responded to shade more than fruit on nongirdled branches. Fruit weight was positively related to percent IPPFD for girdfed but not nongirdled branches shaded 20 to 0 DBH and 44 to DBH. On nongirdled branches, fruit exposed to 45% IPPFD for 44 to 0 DBH had 14% less red color and 21% lower soluble solids content (SSC) than nonshaded fruit. Harvest was delayed >10 days and preharvest fruit drop was increased by shading to <23% IPPFD. Shading branches for 20 to 0 or 44 to 0 DBH altered the relationship between flesh firmness and ground color: Firmness declined as ground color changed from green to yellow for fruit shaded 44 to 20 DBH, but firmness declined with little change in ground color for fruit shaded 20 to 0 or 44 to 0 DBH. Girdling results indicated that fruit weight and SSC partially depended on photosynthate from nonshaded portions of the canopy, whereas fruit redness, days from bloom to harvest, and ground color depended on PPFD in the vicinity of the fruit.

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Fruit Abscission and Fruit Quality of Apples Following Use of Dicamba to Control Preharvest Drop

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.115.3.390 ◽

1990 ◽

Vol 115 (3) ◽

pp. 390-394 ◽

Cited By ~ 2

Author(s):

Richard P. Marini ◽

Ross E. Byers ◽

Donald L. Sowers ◽

Rodney W. Young

Keyword(s):

Fruit Quality ◽

Starch Content ◽

Soluble Solids ◽

Naphthaleneacetic Acid ◽

Soluble Solids Content ◽

Fruit Abscission ◽

Fruit Drop ◽

Solids Content ◽

Methoxybenzoic Acid

Five apple (Malus domestica Borkh.) cultivars were treated with dicamba at concentrations of 0 to 200 mg·liter-1 during 3 years. Although the response varied with cultivar, dose, and year, dicamba always delayed fruit abscission. At similar concentrations, dicamba usually reduced fruit drop more than NAA, but less than fenoprop. Dicamba at 10 mg·liter-1 effectively delayed drop of `Delicious', whereas 20 to 30 mg·liter-1 was required for `Red Yorking', `Rome', `Winesap', and `Stayman'. Dicamba did not influence flesh firmness, soluble solids content, water core, or starch content at harvest or after storage. Chemical names used: naphthaleneacetic acid (NAA); 2-(2,4,5-trichlorophenoxy)propionic acid (fenoprop); 3,6dichloro-2-methoxybenzoic acid (dicamba).

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Effect of time of harvest on alternate cropping yields and fruit quality of Valencia orange trees

Australian Journal of Experimental Agriculture ◽

10.1071/ea9780461 ◽

1978 ◽

Vol 18 (92) ◽

pp. 461 ◽

Cited By ~ 2

Author(s):

PT Gallasch

Keyword(s):

Fruit Quality ◽

South Australia ◽

Mature Fruit ◽

Late Season ◽

Valencia Orange ◽

The Common ◽

Orange Trees ◽

Early Harvest ◽

Time Of Harvest

At Loxton, South Australia, early harvest of heavy, and late harvest of light, Valencia orange crops was compared with the common practice: early harvest of light and late harvest of heavy crops. These treatments were compared with two years of early, mid- or late season harvests. Early harvest of heavy and late harvest of light crops changed the 3.1:1.0 alternate cropping cycle to 1.1:10 and increased the light crop by 101 per cent compared with the common district practice which gave a 3.2 : 10 cycle. Consistent early and mid-season harvests reduced the alternate cropping ratio to 1.3 : 1.0 and 1.4 : 1.0 respectively, produced 14 per cent more fruit than the common district practice and avoided harvesting the light crop late, when fruit quality is poor. Mature fruit weights from trees consistently harvested late were 27 per cent lower than those trees harvested mid-season.

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Midseason oranges for juice production

Australian Journal of Experimental Agriculture ◽

10.1071/ea9931141 ◽

1992 ◽

Vol 32 (8) ◽

pp. 1141 ◽

Cited By ~ 2

Author(s):

RA Sarooshi ◽

RJ Hutton

Keyword(s):

Orange Juice ◽

Sweet Orange ◽

Quality Characteristics ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Juice Quality ◽

Rough Lemon ◽

Large Trees ◽

Production Areas ◽

Troyer Citrange

Juice quality, yield performance, and cropping efficiency of 6 midseason orange varieties (Hamlin, Parramatta, Pineapple, Joppa, White Siletta, and Mediterranean Sweet), together with Seedless Valencia on 4 rootstocks [Troyer citrange, Poncirus trifoliata, rough lemon, and either Benton citrange (coastal) or sweet orange (inland)], were studied for their suitability for both processed and fresh orange juice production. Promising midseason varieties for processed orange juice were Parramatta and Hamlin on Troyer citrange, and Parramatta on P. trifoliata, when grown in coastal districts. Debittered juice of Joppa on Troyer citrange could also be used for processing by early September on the coast. Preferred inland varieties for production of processed orange juice were Mediterranean Sweet and Harnlin on Troyer citrange. Midseason oranges grown inland had higher citric acid levels than the same variety grown on the coast. This resulted in inland fruit having lower ratios of total soluble solids (TSS) to acid, and later maturities, than fruit grown on the coast. Acceptable fresh orange juice was produced from fruit of Parramatta, Hamlin, White Siletta, and Mediterranean Sweet varieties grown on Troyer citrange rootstock in coastal districts; inland, fruit of Mediterranean Sweet, Joppa, Parramatta, and White Siletta varieties on Troyer citrange rootstock produced good quality, fresh orange juice. Hamlin can also be marketed as fresh fruit. In coastal production areas, harvesting can commence from mid July for Hamlin, from mid to late August for Parramata, and from early September for White Siletta and Mediterranean Sweet. Harvest in inland districts for processed juice should commence in mid July for Hamlin and in early September for Mediterranean Sweet, whilst harvest for fresh juice and/or fruit should proceed in early September for Mediterranean Sweet, and in late September for Parramatta, White Siletta, and Joppa. Highest fruit yields and large trees were produced by Parramatta and Joppa on Troyer citrange and rough lemon rootstocks. Most quality characteristics were better for fruit produced on Troyer citrange than on rough lemon. Both Benton citrange and sweet orange performed poorly and are not recommended as rootstocks for midseason oranges. All varieties on Troyer citrange had better yield and TSS/ha than those on P. trifoliata rootstock, which produced smaller but highly cropping efficient trees.

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Rootstocks and the Performance and Economic Returns of ‘Hamlin’ Sweet Orange Trees

HortScience ◽

10.21273/hortsci.45.6.875 ◽

2010 ◽

Vol 45 (6) ◽

pp. 875-881 ◽

Cited By ~ 12

Author(s):

William S. Castle ◽

James C. Baldwin ◽

Ronald P. Muraro

Keyword(s):

Financial Analysis ◽

Sweet Orange ◽

Block Design ◽

Tree Height ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Juice Quality ◽

Volkamer Lemon ◽

C 32 ◽

Orange Trees

‘Hamlin’ is a principal sweet orange grown in Florida for processing. It is productive but produces juice with low soluble solids content and poor color. A long-term trial was conducted in central Florida to determine rootstock effects on yield and juice quality and the effect of economic analysis on the interpretation of the horticultural results. The trees were a commonly used commercial selection of ‘Hamlin’ sweet orange [Citrus sinensis (L.) Osb.] propagated on 19 rootstocks planted in a randomized complete block design of three-tree plots with six replicates in a Spodosol soil at a density of 350 trees/ha. Routine horticultural data were collected from the original trial (H1) for 10 years. Trees on some rootstocks that grew and yielded poorly were removed within a few years and replaced with a second trial (H2) with 13 rootstocks from which data were collected for 5 years. The H1 data were financially analyzed to compare the relative usefulness of horticultural and economic data in interpreting results and making rootstock decisions. In H1 after 10 years, tree height ranged from greater than 5 m [Volkamer lemon (C. volkameriana Ten. & Pasq.)] and Cleopatra mandarin (C. reshni Hort. ex Tan.) to 2.4 m {Flying Dragon trifoliate orange [Poncirus trifoliata (L.) Raf. ]}. In H2, the trees on somatic hybrid rootstocks were ≈2 m tall after 8 years and 4.4 m among those on mandarins and C-32 citrange (C. sinensis × P. trifoliata). Tree losses from citrus blight were generally low except for the trees on Carrizo and Troyer citranges (greater than 50%). Horticulturally, the highest performing trees in H1, measured by cumulative yield and soluble solids production over 10 years, were those on Carrizo, Troyer, and Benton citranges; poor performers were those on Smooth Flat Seville and Kinkoji (putative sour orange hybrids). Fruit yield and soluble solids production were directly related to tree height regardless of the difference among rootstocks in juice quality. The same relationship existed among the trees in H2 in which the best rootstocks were C-32 and Morton citranges. Trees on Swingle citrumelo (C. paradisi Macf. × P. trifoliata) ranked no. 12 of 19 rootstocks and 9 of 13 rootstocks in H1 and H2, respectively. Financial interpretation of the outcomes to include tree replacement resulting from blight losses did not substantially change the horticultural interpretations. Additional financial analyses demonstrated that the performance of trees on rootstocks with relatively low productivity/tree, like those on C-35 citrange and Kinkoji, would equal those on more vigorous rootstocks when tree vigor was properly matched with spacing. Yield determined the economic outcomes and financial analysis aided the interpretation of rootstock horticultural effects but did not greatly alter the relationship among rootstock results. Highly significant correlations between annual and cumulative data indicated that relative rootstock performance among ‘Hamlin’ orange trees in Florida could be reliably determined based on the first 4 cropping years.

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Association between Fruit Development and Mature Fruit Drop in Huanglongbing-affected Sweet Orange

HortScience ◽

10.21273/hortsci14931-20 ◽

2020 ◽

Vol 55 (6) ◽

pp. 851-857

Author(s):

Lisa Tang ◽

Sukhdeep Singh ◽

Tripti Vashisth

Keyword(s):

Fruit Development ◽

Sweet Orange ◽

Water Status ◽

Fruit Size ◽

Substantial Reduction ◽

Fruit Growth ◽

Mature Fruit ◽

Callose Deposition ◽

Immature Fruit ◽

Fruit Drop

In the past decade, FL citrus industry has been struck by Huanglongbing (HLB), a disease caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas). Besides tree decline, HLB causes a sharp increase in mature fruit drop before harvest, leading to a substantial reduction in citrus production. The aim of the study was to provide insights in HLB-associated mature fruit drop. For HLB-affected ‘Valencia’ and ‘Hamlin’ sweet orange (Citrus sinensis), trees exhibiting severe symptoms (“severe trees”) had a significantly higher rate of mature fruit drop compared with mildly symptomatic ones (“mild trees”). Interestingly, dropped fruit were smaller than those still attached to tree branches regardless of the symptom levels of trees; overall, fruit of severe trees were smaller than mild trees. The result suggests a negative effect of HLB on fruit growth that may lead to a high incidence to drop subsequently at maturity. This possibility is further supported by the difference in immature fruit size as early as 2 months after bloom between severe and mild trees. Although HLB-triggered phloem plugging due to callose deposition in citrus leaves, which results in disrupted carbohydrate transport, has been documented in literature, the results of the histological analysis demonstrated no consistent pattern of callose deposition in the mature fruit pedicel in relation to the drop incidence. Additionally, sugar concentration in juice was not significantly different between dropped and attached fruit, providing evidence that carbohydrate shortage is not the case for dropped fruit and thus not the predominant cause of HLB-associated mature fruit drop. Notably, the midday water potential was significantly lower for severe than mild trees during the preharvest period (2 weeks before harvest of the current crop) in late March, which was also the second week after full bloom of return flowering. This suggests that altered tree water status due to HLB might limit fruit growth during the initial stage of fruit development (immediately after flowering) and/or increase the incidence of mature fruit abscission, leading to elevated preharvest fruit drop. Together, the results suggest that in the presence of HLB, strategies to increase fruit size and minimize additional stresses (especially drought) for the trees may improve mature fruit retention.

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Performance of ‘Valencia’ Sweet Orange Trees on 12 Rootstocks at Two Locations and an Economic Interpretation as a Basis for Rootstock Selection

HortScience ◽

10.21273/hortsci.45.4.523 ◽

2010 ◽

Vol 45 (4) ◽

pp. 523-533 ◽

Cited By ~ 25

Author(s):

William S. Castle ◽

James C. Baldwin ◽

Ronald P. Muraro ◽

Ramon Littell

Keyword(s):

Financial Analysis ◽

Sweet Orange ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Juice Quality ◽

Sour Orange ◽

Central Florida ◽

Carrizo Citrange ◽

Acid Ratio ◽

Fruit Samples

Two field experiments with ‘Valencia’ sweet orange [Citrus sinensis (L.) Osb.] trees propagated on 12 rootstocks were conducted in commercial orchards. The objectives were to compare rootstock horticultural performance between two locations with soils representative of the Central Florida Ridge (AP) and coastal flatwoods (I), the major citrus-growing regions in Florida, and to see if financial analysis would provide an improved basis for interpreting rootstock performance. The randomized complete-block trials involved six-tree plots replicated eight or 10 times at planting densities of 358 trees (AP) or 252 trees (I)/ha, respectively. Tree growth and survival, yield, and juice quality were measured for 15 years. When losses occurred, trees were replaced annually with another one on the same rootstock. The data of seven rootstocks were subjected to a financial interpretation of three scenarios: tree loss and tree loss with or without tree replacement using the discounted cash flow and internal rate of return methods at a 15% rate. At the flatwoods location, when differences among replications became apparent on several rootstocks, soil data were collected to study its possible association to tree performance; also in this trial, 400-kg fruit samples were differentially harvested in 2 successive years from mature trees on each of five commercial rootstocks when the juice soluble solids/acid ratio was near 15. The juice was extracted, pasteurized, and evaluated for flavor by an experienced taste panel. The horticultural data obtained for trees on specific well-studied rootstocks [Volkamer (C. volkameriana Ten. & Pasq.)] and rough (C. jambhiri Lush.) lemons, Carrizo citrange [C. sinensis × Poncirus trifoliata (L.)], sour orange [C. aurantium (L.)], Cleopatra mandarin (C. reshni Hort. ex Tan.), trifoliate orange (P. trifoliata), a selection of sweet orange (C. sinensis), and Swingle citrumelo (C. paradisi Macf. × P. trifoliata) at both locations were typical of their well-documented performance in Florida and elsewhere. Tree losses were virtually only from citrus blight and ranged from none (sour orange) to greater than 50% (Volkamer and rough lemons) at both locations, although tree loss began later at the Central Florida location. ‘Valencia’ cuttings (only at the flatwoods site) were long-lived and cropped well for their smaller size compared with the budded trees. Taste panelists were not able to distinguish differences over two seasons among pasteurized ‘Valencia’ juices produced from trees on different rootstocks and normalized by soluble solids/acid ratio. Yield and planting density were the main factors affecting financial outcome; also, in the highly variable soils of the coastal flatwoods, trees growing in sites with greater depth to an argillic layer had 30% to 200% higher yields. Trees on Volkamer lemon had only ≈50% survival at both locations but had the highest ($7,338/ha I) or one of the highest cash flows ($13,464/ha AP) as compared with one of the commercial standards, Carrizo citrange ($6,928 I; $16,826 AP), which had only ≈25% tree loss. Inclusion of financial analysis, with certain limitations, was concluded to considerably improve rootstock selection decisions compared with selection based only on horticultural data.

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Rootstocks Influence Yield Precocity, Productivity, and Pre-Harvest Fruit Drop of Mandared Pigmented Mandarin

Agronomy ◽

10.3390/agronomy10091305 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1305

Author(s):

Marco Caruso ◽

Alberto Continella ◽

Giulia Modica ◽

Claudia Pannitteri ◽

Riccardo Russo ◽

...

Keyword(s):

Fruit Quality ◽

Agricultural Research ◽

Fruit Size ◽

Citrus Fruit ◽

High Sensitivity ◽

Quality Parameters ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Citrus Paradisi ◽

Fruit Drop

Citrus fruit quality and scion productivity are influenced by the choice of rootstock. We aimed to evaluate the effect of rootstocks on yield and fruit quality of Mandared, a triploid pigmented mandarin. To do so, we established a rootstock field trial on a high pH soil (8.6) in which Mandared was grafted onto 11 rootstocks. These included some standard rootstocks, such as trifoliate orange ((Poncirus trifoliata (L.) Raf.), Troyer citrange (Citrus sinensis (L.) Osb. × P. trifoliata), Swingle citrumelo (Citrus paradisi Macf. × P. trifoliata), and C35 citrange (C. sinensis × P. trifoliata), as well as new releases from the Council for Agricultural Research and Economics (CREA, Acireale, Italy) and the University of California Riverside (UCR). The cumulative yield was measured over five consecutive years, while fruit quality was analyzed for two years. The trees on C35, C57 (Citrus sunki Hort. ex. Tan. × P. trifoliata), and C22 (C. sunki × P. trifoliata), started to set fruits one year earlier than the others. The trees on C57 provided some of the highest cumulative yields and canopy volumes. The production of Mandared grafted onto C57 was double that of Mandared grafted onto Troyer, while Mandared grafted onto C35 and C22 resulted in the best yield efficiency. The trees on Swingle and C57 significantly reduced the pre-harvest fruit drop, to which Mandared is particularly sensitive. However, grafting Mandared onto Swingle resulted in the highest variation among replicates, probably due to its high sensitivity to iron chlorosis. Most of the fruit quality parameters, such as fruit size, total soluble solids (TSS), and acidity were not significantly different among the rootstock treatments. However, fruits produced by Mandared grafted onto C22 had one of the highest rates of anthocyanin accumulation. The results indicate that C57, C35, and C22 were the most suitable rootstocks for Mandared in South-Eastern Sicily.

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Soluble Solids Accumulation in `Valencia' Sweet Orange as Related to Rootstock Selection and Fruit Size

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.129.4.0594 ◽

2004 ◽

Vol 129 (4) ◽

pp. 594-598 ◽

Cited By ~ 11

Author(s):

Graham H. Barry ◽

William S. Castle ◽

Frederick S. Davies

Keyword(s):

Sweet Orange ◽

Fruit Size ◽

Poncirus Trifoliata ◽

Soluble Solids ◽

Quality Data ◽

Juice Quality ◽

Direct Role ◽

Size Category ◽

Carrizo Citrange ◽

Rough Lemon

Juice quality of `Valencia' sweet orange [Citrus sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks was determined for fruit harvested by canopy quadrant and separated into size categories to ascertain the direct role of rootstock selection on juice soluble solids concentration (SSC) and soluble solids (SS) production per tree of citrus fruit. SS production per fruit and per tree for each size category was calculated. Juice quality was dependent on rootstock selection and fruit size, but independent of canopy quadrant. Fruit from trees on Carrizo citrange had >20% higher SSCs than fruit from trees on rough lemon, even for fruit of the same size. Large fruit accumulated more SS per fruit than smaller fruit, despite lower juice content and SSC. Within rootstocks, SS content per fruit decreased with decreasing fruit size, even though SSC increased. Rootstock effect on juice quality was a direct rather than an indirect one mediated through differences in fruit size. The conventional interpretation of juice quality data that differences in SSC among treatments, e.g., rootstocks or irrigation levels, or fruit size, are due to “dilution” of SS as a result of differences in fruit size and, hence, juice volume, is only partly supported by these data. Rather, accumulation of SS was greater for fruit from trees on Carrizo citrange than rough lemon by 25% to 30%.

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