Unshiu Marcovitch Research Articles

Differential Impacts of Citrus Thrips Across Sweet Orange and Mandarin Species.

Several domesticated Citrus species are grown as major commercial crops in California. Despite this, farmers currently use a single set of management practices, originally created for sweet oranges (Citrus sinensis (L.) Osbeck [Sapindales: Rutaceae]), for both sweet oranges and all mandarin species. Mandarins, primarily Citrus reticulata Blanco, Citrus clementina hort. ex Tanaka, and Citrus unshiu Marcovitch, comprise almost 25% of California citrus acreage, and little work has been done to assess host-pest interactions for these species. Citrus thrips (Scirtothripscitri Moulton [Thysanoptera: Thripidae]) are one of the main pests in California citrus and are major targets for early spring, "petal fall" insecticide applications. We used mixed species citrus blocks to test the influence of Citrus species, including C. sinensis, C. reticulata, C. clementina, and C. unshiu, on 1) citrus thrips densities following petal fall; 2) citrus thrips-induced scarring on both the calyx and stylar ends of fruit; and 3) fruit deformation. Citrus sinensis and C. unshiu had relatively high citrus thrips densities and scarring levels, whereas C. reticulata had lower densities of citrus thrips and scarring levels. The age structure of citrus thrips populations also varied across Citrus species. Fruit deformity associated with citrus thrips scarring was found on all Citrus species examined. Scarring on the stylar-end of fruit, a previously largely ignored location of citrus thrips scarring, was found to be common in C. reticulata. It is clear from our work that species-specific management guidelines for citrus thrips are needed in sweet oranges and mandarins.

Yield, Tree Size, and Fruit Quality of Mature ‘Owari’ and ‘Brown Select’ Satsuma on Poncirus trifoliata ‘Rubidoux’ and ‘Flying Dragon’ Rootstocks in North Florida

There is increasing interest in the culture of satsuma citrus in the states bordering the northern Gulf of Mexico. Yield, tree size, and fruit quality of mature ‘Owari’ and ‘Brown Select’ satsuma (Citrus unshiu Marcovitch) on Poncirus trifoliata (L.) Raf. (‘Rubidoux’ and ‘Flying Dragon’) were evaluated in north Florida. Canopy area and volume, yield, and fruit quality data were analyzed as a 2 × 2 factorial design with scion and rootstock as the main effects. There were no scion × rootstock interactions. Overall average yield per tree was 16, 88, 91, 143, and 101 kg in 2010, 2011, 2012, 2013, and 2014, respectively. Yield was influenced by scion (higher for ‘Brown Select’) in three of five years, and by rootstock every year (higher for ‘Rubidoux’). Yield per tree was ≈2-fold greater for trees on ‘Rubidoux’ compared with ‘Flying Dragon’; the highest yield was recorded for ‘Brown Select’ on ‘Rubidoux’. Yield per m2 canopy area was often similar since canopy area was often ≈2-fold greater for trees on ‘Rubidoux’. For three of the five years, fruit weight was greater for ‘Brown Select’ (average = 157 g) than ‘Owari’ (average = 146 g), with no rootstock effect. Soluble solids of juice averaged 10.0 °Brix and were higher for trees on ‘Flying Dragon’ than on ‘Rubidoux’ in three of five years. Juice pH averaged 3.67 and was unaffected by scion or rootstock. Trees were not subjected to freeze protection and were not damaged by minimum temperatures as low as −9.4 °C, except for 2014/15. A rating of defoliation after a freeze on 19 Nov. 2014 (−5.6 °C) indicated that cold hardiness varied by scion (greater for ‘Brown Select’) and rootstock (greater for ‘Rubidoux’). Differences in cold hardiness did not persist when assessed later in the winter. Successful satsumas production can be achieved in north Florida in the absence of a severe freeze event.

Diversity among mandarin varieties and natural sub-groups in aroma volatiles compositions.

Mandarins constitute a large, diverse and important group within the Citrus family. Here, we analysed the aroma volatiles compositions of 13 mandarin varieties belonging to seven genetically different natural sub-groups that included common mandarin (C. reticulata Blanco), clementine (C. clementina Hort. ex. Tan), satsuma (C. unshiu Marcovitch), Mediterranean mandarin (C. deliciosa Tenore), King mandarin (C. nobilis Loureiro), and mandarin hybrids, such as tangor (C. reticulata × C. sinensis) and tangelo (C. reticulata × C. paradisi). We found that mandarin varieties among tangors ('Temple', 'Ortanique'), tangelos ('Orlando', 'Minneola') and King ('King') had more volatiles, at higher levels, and were richer in sesquiterpene and ester volatiles, than other varieties belonging to the sub-groups common mandarin ('Ora', 'Ponkan'), clementine ('Oroval', 'Caffin'), satsuma ('Okitsu', 'Owari') and Mediterranean mandarin ('Avana', 'Yusuf Efendi'). Hierarchical clustering and principal component analysis accurately differentiated between mandarin varieties and natural sub-groups according to their aroma-volatile profiles. Although we found wide differences in aroma-volatiles compositions among varieties belonging to different natural sub-groups, we detected only minor differences among varieties within any natural sub-group. These findings suggest that selecting appropriate parents would enable manipulation of aroma-volatile compositions in future mandarin breeding programmes.

Diversity in sensory quality and determining factors influencing mandarin flavor liking.

We evaluated the sensory quality of 42 mandarin varieties that belong to 7 different natural subgroups: common mandarin (Citrus reticulata Blanco), Clementine (Citrus clementina Hort. ex. Tan), Satsuma (Citrus unshiu Marcovitch), Mediterranean mandarin (Citrus deliciosa Tenore), King mandarin (Citrus nobilis Loureiro), and mandarin hybrids, such as tangor (Citrus reticulata × Citrus sinensis) and tangelo (Citrus reticulata × Citrus paradisi). Consumer flavor acceptance tests revealed wide diversity in flavor preferences among mandarin varieties and subgroups. Furthermore, descriptive flavor-analysis tests conducted with the aid of a trained sensory panel revealed that the 9 most preferred varieties had similar flavor profiles, characterized by high sweetness, moderate to low acidity levels, low bitterness and gumminess, strong fruity and mandarin flavor, and high juiciness. The average total soluble solids (TSS) and acidity levels among the highly preferred varieties were 13.1% and 1.1%, respectively. In contrast, the 8 least preferred varieties were either too sour or gummy or had low levels of sweetness, fruity, or mandarin flavor, and either high acidity levels (>1.4%) or low TSS levels (<12.0%). Pearson tests revealed significant positive correlations between flavor acceptance and perceptions of sweetness, fruitiness, and mandarin flavor, and negative correlations with acidity levels and perceptions of sourness, bitterness, and gumminess. Principle component analysis clearly distinguished between highly accepted varieties that were tightly correlated with high TSS levels and perceptions of sweetness fruitiness and mandarin flavor, as compared with the least accepted varieties that were correlated with high acidity levels and perceptions of sourness, bitterness, and gumminess.

Cold Tolerance of the Mediterranean Fruit Fly in Date and Mandarin.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is an endemic pest in Israel and there can be low levels of infestation of dates (Phoenix dactylifera L.). Because C. capitata is considered a quarantine pest by several major importing countries, the export of fresh dates requires the elimination of this pest. For mandarin, cold storage at 1.11°C for 15 d is considered to be an effective treatment for the elimination of C. capitata. In this study, we compared the cold tolerance of C. capitata in "Barhi" dates to that of C. capitata in mandarins (Citrus unshiu Marcovitch, "Satsuma"). In Barhi dates, we found the third instars to be the most cold-tolerant as compared with other life stages. Ceratitis capitata in date fruits were significantly less cold-tolerant than C. capitata in Satsuma mandarins. The last viable larvae in dates and mandarins were found after 8 and 13 d of treatment, respectively, and the calculated mortality curves in the two crops were significantly different. These results demonstrate that C. capitata is more sensitive to cold treatment when in date fruits than in mandarins. Therefore, the quarantine cold treatments used to eliminate C. capitata from mandarins should be sufficiently effective if applied to fresh date fruits.

Genetic diversity among mandarins in fruit-quality traits.

A detailed phenotypic analysis of fruit-quality traits was conducted among 46 mandarin varieties within the Israeli Citrus breeding collection, belonging to genetically different natural subgroups, including common mandarin (C. reticulata Blanco), clementine (C. clementina Hort. ex. Tan), satsuma (C. unshiu Marcovitch), Mediterranean mandarin (C. deliciosa Tenore), King mandarin (C. nobilis Loureiro), and mandarin hybrids, such as tangor (C. reticulata × C. sinensis) and tangelo (C. reticulata × C. paradisi). Evaluated qualities included physical attributes (size, shape, color, peel thickness, and seed number); physiological properties (ripening period, peelability, and segmentation); nutritional and biochemical composition (vitamin C, phenol, flavonoid, and carotenoid contents and total antioxidant activity); and sensory attributes (total soluble solids and acid levels, flavor preference, sweetness, sourness, and fruitiness). The results indicated wide genetic variability in fruit-quality traits among mandarin varieties and natural subgroups, and statistical and hierarchical clustering analysis revealed multiple correlations among attributes. Such phenomic analysis is an obligatory requirement for identification of molecular markers for distinct fruit-quality traits and for selection of appropriate parents for future breeding programs.

Evaluation of damage to satsuma mandarin (Citrus unshiu) by the leaffooted bug, Leptoglossus zonatus (Hemiptera: Coreidae)

AbstractThe leaffooted bug, Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) is a key direct pest of satsuma mandarin (Citrus unshiu Marcovitch) in much of the Gulf Coast region of the United States. The injury and amount of damage to satsuma fruit caused by L. zonatus adults and nymphs at various insect densities (0–3 individuals per fruit) and feeding durations (0–14 days after infestation) were assessed in laboratory and field experiments. The parameters evaluated included fruit damage symptoms, fruit colour, premature fruit abortion (PFA), fruit weight loss (FWL), percentage of damaged sections (PDS), and soluble solids content (SSC) of the fruits. Feeding by L. zonatus on satsuma produced typical damage symptoms including the presence of green spots and dark spots on the outer rind and the collapsing and drying out of the juice vesicles in the inner rind. Insect density and feeding duration had significant effects on most damage parameters. Fruit weight loss and PDS increased with insect density and feeding duration. Soluble solids content decreased with both factors, and was also negatively correlated to PDS. Premature fruit ripening (yellowing) was recorded at densities of 1 or more insects per fruit. Premature fruit abortion was significantly higher in fruits infested by L. zonatus than in uninfested fruits, but insect density may not fully explain the PFA data. Leptoglossus zonatus female and male produced similar amounts of damage, which were slightly more than the damage produced by the nymphs. In general, the results were fairly consistent between laboratory and field experiments, although some minor differences were recorded. The data suggest an economic injury level of 1–2 L. zonatus per satsuma fruit. The results are discussed in relation to the ecology and management of L. zonatus on satsuma.

Exclusion experiments reveal relative contributions of natural enemies to mortality of citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae) in Alabama satsuma orchards

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is an important pest of satsuma mandarin ( Citrus unshiu Marcovitch) in Alabama. A recent study identified several species of beneficial arthropods including spiders (e.g., Hibana sp.), ants (e.g., Solenopis invicta Buren), Chrysoperla sp., Harmonia axyridis Pallas, and two parasitoid species ( Ageniaspis citricola Logvinovskaya and Cirrospilus sp.), as potential natural mortality factors of P. citrella in Alabama. Exclusion experiments with complete or timed (early or later) sticky or cage barriers were conducted in two satsuma orchards in southern Alabama during 2007 and 2008 to determine the relative contributions of key beneficial arthropods to natural mortality of P. citrella. Overall mortality of P. citrella on unprotected (control) satsuma tree branches ranged from ∼39%–52% depending on location and year. Results from both locations and years clearly showed that predation was the dominant natural mortality factor acting on P. citrella. Predation accounted for ∼87–96% of all deaths on unprotected (control) satsuma tree branches. In particular, predation by spiders was the single most important mortality element, which accounted for ∼50–70% of all deaths. Predation by ants was second, accounting for ∼10–19% of all deaths. Predation by predatory insect larvae accounted for ∼3–27% of all mortalities, while parasitism contributed the least (0–10%) to P. citrella mortality. Predation by spiders was excluded by a cage barrier, whereas a sticky barrier was more effective in excluding predation by ants. In general, the timed barrier treatments were not as effective in excluding the key predatory arthropods. These results are discussed in relation to the management of P. citrella in Alabama satsuma orchards.

Aroma Character Impact Compounds in Kinokuni Mandarin Orange (Citrus kinokuni) Compared with Satsuma Mandarin Orange (Citrus unshiu)

The odor-active volatiles of Kinokuni mandarin (Citrus kinokuni Hort. ex Tanaka), an original mandarin orange in Japan, were characterized by a combination of instrumental and sensory analyses and compared with those of Satsuma mandarin (Citrus unshiu Marcovitch). An aroma extract dilution analysis (AEDA) of the polar fractions of Kinokuni and Satsuma mandarin peel oils identified five odorants in common as the most odor-active volatiles: (Z)-hex-3-enal, decanal, linalool, yuzuol, and (2E)-trans-4,5-epoxydec-2-enal. In addition, seven odorants were identified solely in Kinokuni mandarin as significant contributors: octanal, dodecanal, (2E,4E)-deca-2,4-dienal, geraniol, yuzunone, (2E,7Z)-trans-4,5-epoxydeca-2,7-dienal, and thymol. The odor-active volatiles in both the non-polar components of the peel oil and an extract of the juice prepared from Kinokuni mandarin were also identified. The (S)-isomer of linalool in Kinokuni mandarin peel oil was dominant in the enantiomeric distribution (92%), whereas the (R)-isomer was dominant in Satsuma mandarin peel oil (90%).

Functional responses and prey-stage preferences of three species of predacious mites (Acari: Phytoseiidae) on citrus red mite, Panonychus citri (Acari: Tetranychidae)

The citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), is a pest of citrus worldwide, and a major pest of satsuma mandarin ( Citrus unshiu Marcovitch) in Alabama. This study was conducted to evaluate the potential of three commercially available predacious mite species (Acari: Phytoseiidae), Phytoseiulus persimilis Athias-Henriot, Galendromus occidentalis (Nesbitt), and Neoseiulus californicus (McGregor), as biological control agents of P. citri. The functional responses (at densities ranging from 2 to 150 P. citri immature per leaf disc arena) and prey-stage preferences (when offered varying ratios of P. citri eggs and nymphs) of the phytoseiids were investigated in laboratory experiments. All three species were modestly effective in regulating P. citri nymph density, but very few eggs were laid by each on the prey. Logistic regression analysis suggests a Type II (convex) functional response for all three species: the number of prey consumed increased with prey availability up to a maximum point after which it slowly began to decrease. The maximum daily predation was recorded at a prey density of 75 P. citri nymphs per arena for female P. persimilis and G. occidentalis, and at a density of 100 nymphs per arena for female N. californicus. Results from experiments on prey-stage preferences showed that all three phytoseiids preferred nymphs to eggs of P. citri. Food deprivation for up to 48 h had no significant effect on the number of prey consumed or the prey-stage preferences of the phytoseiids. Among the three species, P. persimilis had the highest predation potential, in particular at high prey densities. These results are discussed in relation to the feeding habits and specialization of the phytoseiids and their potential for biological control of P. citri in citrus orchards.

Determining the water status of Satsuma mandarin trees [ Citrus Unshiu Marcovitch] using spectral indices and by combining hyperspectral and physiological data

This study investigated the water relations of Satsuma mandarin trees [ Citrus Unshiu Marcovitch] and drought stress indicators used for irrigation scheduling in orchards namely: (1) the midday leaf water potential (MLWP), (2) midday stem (or xylem) water potential (MSWP), (3) predawn leaf water potential and (4) the leaf water content. Remote sensing spectral indices were applied to predict these indicators for trees subjected to different drought stress regimes. Continuous measurements of the MLWP and the MSWP on individual trees during cloudless days showed large fluctuations in the MLWP of up to 2.0 MPa and less variation in the MSWP of ∼0.30 MPa. The large variability in the MLWP was directly related to stomatal oscillations characteristic of most citrus species and the MSWP measurements were more representative of the tree water status. Spectral indices derived from canopy reflectance data of mature citrus trees in the orchard showed poor correlations with both the MSWP and MLWP. However, using spectral indices from the leaf reflectance of young potted citrus trees showed that the water index (WI) and a narrow-band spectral ratio of the reflectance at 960 and 950 nm wavelengths gave the best predictions of the MSWP with R 2 = 0.77 and 0.79, respectively but only for severely stressed trees. All the indices failed to predict the water potentials of trees with mild or no drought stress ( R 2 < 0.20), although the leaf water content predictions were accurate for both stressed and non-severely stressed trees. Integrating the hyperspectral estimates of leaf water content with the transpiration and soil water potential data in a simple dynamic tree-level water balance model yielded more accurate estimates of the MSWP of non-severely stressed trees. This suggests that in the absence of robust spectral indices for predicting plant water status, as is the case at present, combining hyperspectral remote sensing and in situ data in physiological models potentially yields useful information for irrigation management in orchards.

Host Preference and Development of &lt;I&gt;Leptoglossus zonatus&lt;/I&gt; (Hemiptera: Coreidae) on Satsuma Mandarin

Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) has recently emerged as a key pest of satsuma mandarin, Citrus unshiu Marcovitch, and other fruit crops in the Gulf Coast region of the United States. Studies were conducted under laboratory conditions (25 +/- 2 degrees C, 50 +/- 10% RH, and a photoperiod of 14:10 [L:D] h) to investigate host preference and suitability of satsuma fruit as host for this pest. Three separate multiple choice experiments were performed to compare attraction of L. zonatus nymphs and adults to the fruit of tomato, Solanum lycopersicum L.; satsuma mandarin; peach, Prunus persica (L.) Batsch; kumquat (Fortunella spp.); and lemon, Citrus limon (L.) Burm. F. Results of all three experiments clearly showed that tomato was the most preferred by both the nymphs and adults, with satsuma a distant second. Attraction to tomato and satsuma fruit was not due mainly to color but mediated by host volatile semiochemicals (kairomones). Developmental experiments with L. zonatus on satsuma fruit suggest that it is a suitable host that can maintain modest to high populations of the pest. Approximately 39 eggs were deposited per female on satsuma fruit with a hatch rate of 98%. Total developmental time from egg through the fifth nymphal stage was approximately = 50 d. High survivorship was recorded for all stages and ranged from 100% for the fourth instars to approximately = 89.1% for second instars. Cumulative survivorship from eggs through the fifth stage was 75.6%. Sex ratio (female:male) of emerged adults was 1:1.03, and female longevity (approximately = 73 d) was significantly greater than male longevity (57 d). Other aspects of the developmental biology of L. zonatus on satsuma are described, and the results are discussed in relation to the field ecology of the pest.

Effect of leguminous cover crops on soil biological activity in pots of Citrus unshiu Marcovitch

Little is known about the effects of cover crops on soil properties in citrus orchards. To fill this gap, this work was aimed to determine the effects of leguminous cover crops on the chemical and biological properties of the soil and on the structure of the microbial community in pots of Citrus unshiu (Marcovitch). After amendment with cover crops, an increase in total organic C (TOC), total extractable C (TEC), and total N (TN) contents were observed irrespective of the type of soil. Substrate induced respiration (SIR), and potentially mineralisable nitrogen (PMN), tested three times in one year, were higher in soils with leguminous cover crops while no significant differences were observed in protease and deaminase activity. The effect on the chemical and biochemical properties of the soil was more evident in plots containing Trifolium subterraneum. No changes were observed in the microbial communities studied (_-proteobacteria, _-proteobacteria, nitrogen-fixing, and ammonia oxidizers) irrespective of the kind of cover crop or type of soil, neither were variations noted during the trial.

Differences in Host Preference, Life Cycle Pattern, and Insecticide Susceptibility Among &lt;I&gt;Aphis gossypii&lt;/I&gt; Clones and Genetic Relationships Inferred from Internal Transcribed Spacer 2 Sequences of rDNA

As part of an analysis of the genetic structure of Aphis gossypii Glover, one of the most polyphagous aphids and a pest of global agricultural importance, the ITS2 rDNA region was sequenced and compared among 38 Japanese aphid clones with different life cycles, host preferences, and insecticide susceptibilities. The preference of each clone for cucumber (Cucumis sativus L.), eggplant (Solanum melongena L.), citrus (Citrus unshiu Marcovitch), and pear (Pyrus pyrifolia Nakai) as a host was tested. About two thirds of the clones preferred cucumber or eggplant. No other particular combination of host plants was preferred. Five types of life cycle were found: holocyclic I, holocyclic II, intermediate, androcyclic, and anholocyclic. Each clone showed a different level of susceptibility to each of three insecticides. Apparent correlation between the various attributes was not found. Phylogenetic trees constructed from internal transcribed spacer 2 sequences showed ambiguous relationships between genetic differentiation and host preference.

Characterization of the pectin extracted from citrus peel in the presence of citric acid

Pectins were extracted from the peel of Citrus unshiu Marcovitch × C. nobilis Loureiro (Kara mandarin) in the presence of citric acid at different pH and temperature. Treatment with citric acid, particularly, at neutral pH gave a significant increase in viscosity. The citric acid treatment at high temperature led to decreased viscosity although the viscosity remained higher than that of untreated pectin. Pectin methylesterase activity was inhibited at high citric acid concentrations. The increase in viscosity of treated pectin was proportional to the amounts of citric acid bound to pectin. The pectin with citric acid treatment had a low degree of methylation (8.4%) and a high distribution (50 to 2000 kDa) of molecular mass than untreated pectin. Analysis of chemical composition showed that the pectin with citric acid treatment contained lower protein and galacturonic acid, and higher neutral sugars, particularly, galactose than the untreated pectin. The citric acid treatment at neutral pH prior to extraction is an attractive procedure for low methoxy pectin without lowering its molecular weight.

Vetiver oil and nootkatone effects on the growth of pea and citrus

Studies have indicated that vetiver oil and one of its components, nootkatone, possess insecticidal and herbicidal activities. The compounds appear to be good candidates as novel pesticides for substrate (soil, wood, and mulch) treatments. Phytotoxicity is a concern for substrate treatment agents against soil dwelling organisms. Using treated potting media the phytotoxic effect of vetiver oil and nootkatone was evaluated on the pea plants ( Pisum sativum L.; cv, “Kelvedon Wonder”) in the laboratory and on citrus trees ( Citrus unshiu Marcovitch) under field conditions. All the tested chemicals at various concentrations (20, 500, and 2000 μg/g soil) reduced the pea plant growth (plant height, root length, dry weight). Nootkatone treatments had the lowest inhibitory effect on growth, followed by vetiver oil and disodium octaborate tetrahydrate (Tim-bor ®), a registered pesticide with known phytotoxicity. The most inhibitive and injurious effects occurred with Tim-bor ® at concentrations of 500 and 2000 μg/g soil, causing plant mortality of up to 38.9%. No pea plant mortality was observed in nootkatone and vetiver oil treatments. Vetiver oil and nootkatone treatments at the rates of 30 and 100 μg/g potting media had no adverse effect on the citrus plant growth rates. These results support the possible usage of the two chemicals around buildings and in nurseries for the management of termites, ants, and weeds; or in the nursery industry where quarantines may be in place to prevent the movement of invasive pests.

Genetic similarity of citrus fresh fruit market cultivars

The objective of this work was to assess the genetic similarity of the following citrus fresh fruit market seedless cultivars: Lane Late, Navelate, Navelina and Salustiana sweet oranges (Citrus sinensis (L.) Osbeck), Clemenules and Marisol mandarins (C. reticulata Blanco) and Okitsu satsuma mandarin (C. unshiu Marcovitch), and the hybrids Nova [C. clementina x (C. paradisi x C. tangerina)] and Ortanique (tangor probably derived from C. sinensis (L.) Osbeck x C. reticulata Blanco), utilizing isoenzymatic markers. Electrophoresis analysis of proteins extracted from leaf tissues was utilized to detect polymorphisms at ten isoenzymatic systems. Out of 30 alleles, 16 were polymorphic. The Jaccard coefficient was utilized to estimate the genetic similarity between the cultivars and the unweigthed pair-group method using an arithmetic average (UPGMA) was used to obtain the phenogram (NTSYS 1.7). The cultivars showed high genetic similarity (&gt;72.5%), and were classified in five main groups: sweet oranges, 'Clemenules' and 'Marisol' mandarins, 'Nova', 'Ortanique', and 'Okitsu' satsuma mandarin.

'LA Early': A New Early Marketing Satsuma Mandarin

‘LA Early’ (Fig. 1), a new early maturing satsuma mandarin cultivar (Citrus unshiu Marcovitch), is a product of the Louisiana State Univ. (LSU) AgCenter citrus research program. The objective of the program is to develop fresh market lines of citrus fruits (navels, satsumas, and other cultivars) with improved quality, fruit characteristics, and production (Bourgeois et al., 1993, 1995; Brown et al., 1976; Reuther et al., 1967). ‘LA Early’, field tested as ‘LA3-3’, is an improved quality satsuma mandarin that ripens in early September to mid-October.

Studies on the preparation and evaluation of kijitsu, the immature citrus fruits. I. Evaluation of the new drying method

To establish the preparing method of the crude drug, kijitsu, 8 kinds of unripe citrus fruit including Citrus unshiu MARCOVITCH as well as C. aurantium L. subsp.amara ENGLER or C. natsudaidai HAYATA were divided horizontally in two parts and dried under the sun-shine or with hot air below 50°C. Four flavonoids (narirutin, naringin, hesperidin and neohesperidin) were determined by high performance liquid chromatography. Flavonoid content of kijitsu prepared with hot air was about 1.5-times that by solar drying. Most of flavonoid was contained in albedo-free peel. Hot air drying gave fine fragrance and greenish color to kijitsu. Furthermore, it saved labor and time compared with the solar drying method.

The effect of synthetic auxins on fruit growth and anatomical development in ‘Satsuma’ mandarin

The application of a mixture of the synthetic auxins 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid increased fruit size in ‘Satsuma’ mandarin ( Citrus unshiu Marcovitch). Peak response was obtained when the auxin mixture was applied 26 days after flower opening. At that time, the percentage of the fruit cross-sectional area occupied by the peel was maximum, the juice sacs just filled the locular cavity and the rate of expansion of the locular cavities started increasing rapidly. The synthetic auxins had a direct stimulatory effect on fruit growth, and no thinning effect was found at the concentration used (7.5 mg l −1). Differences in weight between the treated and control fruit increased with time until maturity. The growth of both the peel and the pulp segments was stimulated initially to the same extent, but at maturity the treated fruit had a smaller percentage of peel despite its bigger size. Peel puffiness was reduced by the auxin applications.