Tree performance and fruit yield and quality of `Okitsu` Satsuma mandarin grafted on 12 rootstocks

The citriculture in Brazil, as well as in other important regions in the world, is based on very few mandarin cultivars. This fact leads to a short harvest period and higher prices for off-season fruit. The `Okitsu` Satsuma (Citrus unshiu Marc.) is among the earliest ripening mandarin cultivars and it is considered to be tolerant to, citrus canker (Xanthomonas citri subsp. citri Schaad et al.) and to citrus variegated chlorosis (Xylella fastidiosa Wells et al.). Despite having regular fruit quality under hot climate conditions, the early fruit maturation and absence of seeds of `Okitsu` fruits are well suited for the local market in the summer(December through March), when the availability of citrus fruits for fresh consumption is limited. Yet, only a few studies have been conducted in Brazil on rootstocks for `Okitsu`. Consequently, a field trial was carried out in Bebeclouro, Sao Paulo State, to evaluate the horticultural performance of `Okitsu` Satsuma mandarin budded onto 12 rootstocks: the citrandarin `Changsha` mandarin (Citrus reticulata Blanco) x Poncirus trifoliata `English Small`: the hybrid Rangpur lime (Citrus limonia Osbeck) x `Swingle` citrumelo (P. trifoliata (L.) Raf. x Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L) Raf)`Rubidoux`,`FCAV` and `Flying Dragon`(P. trifoliata var. monstrosa); the mandarins `Sun Chu Sha Kat`(C. reticulata Blanco) and `Sunki`(Citrus sunki (Hayata) Hort. ex. Tanaka); the Rangpur limes (C. limonia Osbeck) `Cravo Limeira` and `Cravo FCAV`;`Carrizo` citrange (Citrus sinensis x P. trifoliata), `Swingle` citrumelo (P. trifoliata x C. paradisi), and `Orlando` tangelo (C. paradisi x Citrus tangerina cv. `Dancy`). The experimental grove was planted in 2001, using a 6 m x 3 m spacing, in a randomized block design. No supplementary irrigation was applied. Fruit yield, canopy volume, and fruit quality were assessed for each rootstock. A cluster multivariate analysis identified three different rootstock pairs with similar effects on plant growth, yield and fruit quality of `Okitsu` mandarin. The `Flying Dragon `trifoliate had a unique effect over the `Okitsu` trees performance, inducing lower canopy volume and higher yield efficiency and fruit quality, and might be suitable for high-density plantings. The `Cravo Limeira` and `Cravo FCAV` Rangpur limes induced early-ripening of fruits, with low fruit quality. `Sun Chu Sha Kat` and `Sunki` mandarins and the `Orlando` tangelo conferred lower yield efficiency and less content of soluble solids for the latter rootstock. (C) 2009 Elsevier B.V. All rights reserved.

Horticultural performance of `Folha Murcha` sweet orange onto twelve rootstocks

Despite its outstanding position, the Brazilian citriculture is established on a very limited pool of varieties that limits its expansion and restricts the fruit availability throughout the year. This situation determines the urgent necessity of developing alternative scion and rootstock cultivars, with good performance under local conditions. `Folha Murcha` sweet orange (Citrus sinensis (L.) Osbeck) is a late-harvest cultivar, suitable both for the juice processing industry and the fresh fruit market, being described as tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.), and less affected by citrus variegated chlorosis (Xylella fastidiosa Wells et al.). A study was conducted in Bebedouro, Sao Paulo State, Brazil, to evaluate the horticultural performance of `Folha Murcha` sweet orange budded onto 12 rootstocks: the citrandarin `Changsha` mandarin (Citrus reticulata Blanco) x Poncirus trifoliata `English Small`: the hybrid `Rangpur` lime (Citrus limonia Osbeck) x `Swingle` citrumelo (P. trifoliata (L.) Raf x Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.)`Rubidoux`, `FCAV`, and `Flying Dragon` (P. trifoliata var. monstrosa); the `Sun Chu Sha Kat` mandarin (C. reticulata Blanco); the `Sunki` mandarin (Citrus sunki (Hayata) Hart. ex. Tanaka); the `Rangpur` limes (C. limonia Osbeck) `Cravo Limeira` and `Cravo FCAV`; `Carrizo` citrange (C. sinensis x P. trifoliata), `Swingle` citrumelo (P. trifoliata x C. paradisi), and `Orlando` tangelo (C. paradisi x Citrus tangerina cv. `Dancy`). The experimental grove was planted in 2001, using a 7 m x 4 m spacing, in a randomized block design, with five replications and two plants per plot. No supplementary irrigation was applied. Fruit yield, canopy volume, tree tolerance to drought and to citrus variegated chlorosis, and fruit quality were assessed for each rootstock. Trees grafted onto the `Flying Dragon` trifoliate were smaller in size, but had largest yield efficiency when compared to those grafted onto other rootstocks. Lower alternate bearing index was observed on trees budded onto `Cravo FCAV` `Rangpur` lime. Both `Rangpur` lime rootstocks and the `Sunki` mandarin induced higher tree tolerance to drought. The `Flying Dragon` trifoliate induced better fruit quality and higher tolerance to citrus variegated chlorosis (CVC) to `Folha Murcha` trees. A cluster multivariate analysis identified three groups of rootstocks with similar effects on `Folha Murcha` tree performance. Among the 12 evaluated rootstocks, the `Flying Dragon` trifoliate has a unique effect on plant growth, tolerance to drought and CVC, fruit yield and fruit quality of `Folha Murcha` trees, and may be better suited for high-density plantings. (C) 2011 Elsevier B.V. All rights reserved.

`Swingle` citrumelo propagation by cuttings for citrus nursery tree production or inarching

`Swingle` citrumelo [Citrus paradisi MacFaden x Poncirus trifoliata (L.) Raf.] has been extensively used as a rootstock in several citrus growing regions of the World, including Southern Brazil where `Rangpur` lime (Citrus limonia Osbeck) is still the predominant variety despite being affected by several important pathogens. in this case, `Swingle` citrumelo is used to produce nursery trees to establish new orchards or to be inarched in adult and healthy groves in order to change the rootstock. We report herein a system to produce trees on `Swingle` citrumelo more rapidly by budding onto non-rooted cuttings, as well as assessing potential to rapidly multiply `Swingle` through rooting of non-budded cuttings. Therefore, two potential products are described: budded trees and rooted rootstock cuttings. `Valencia` sweet orange [Citrus sinensis (L.) Osbeck] was budded at different heights on cuttings derived from eight-month old rootstocks. Grafted and additional non-budded cuttings were then treated with indole-3-butyric acid (500 mg L(-1)) or left untreated before rooting. Three types of cuttings were evaluated: softwood, semi-hardwood and hardwood. The use of nursery trees derived from pre-budded hardwood cuttings of `Swingle` citrumelo is an alternative grafting method on this cultivar. Softwood cuttings with one leaf pair were considered the most adequate material for rapid multiplication of `Swingle` citrumelo by cutting. This could be particularly useful for inarching production or conventional budding after transplant of cutting-derived rootstocks. (C) 2008 Elsevier B.V. All rights reserved.

Low glyphosate rates do not affect Citrus limonia (L.) Osbeck seedlings

BACKGROUND: Glyphosate is used to control weeds in citrus orchards, and accidental spraying or wind drift onto the seedlings may cause growth arrest owing to metabolism disturbance. Two experiments were carried out to investigate the effect of non-lethal rates (0, 180, 360 and 720 g Al ha(-1)) of glyphosate on four-month-old `Cravo` lime, Citrus limonia (L.) Osbeck, seedlings. Photosynthesis and the concentrations of shikimic acid, total free amino acids and phenolic acids were evaluated. RESULTS: Only transitory effects were observed in the! contents of shikimate and total free amino acids. No visual effects were observed. CONCLUSION: The present study showed that glyphosate at non-lethal rates, which is very usual when accidental spraying or wind drift occurs in citrus orchard, did not cause severe metabolic damage in `Cravo` lime seedlings. (C) 2009 Society of Chemical Industry

Evaluation of citrus somatic hybrids for tolerance to Phytophthora nicotianae and citrus tristeza virus

Somatic hybridization is a biotechnology tool that can be used in citrus breeding programs to produce somatic hybrids with the complete genetic combination of both parents. The goal of this work was to test the reaction of citrus somatic hybrids that may be useful as rootstocks to trunk and root infections caused by Phytophthora nicotianae van Breda de Haan (P parasitica Dastur) and to citrus tristeza virus (CTV). The somatic hybrids evaluated were `Caipira` sweet orange (Citrus sinensis L. Osbeck) + `Rangpur` lime (C. limonia Osbeck), `Caipira` sweet orange + `Cleopatra` mandarin (C. reshni hort. ex Tanaka), `Caipira` sweet orange + `Volkamer` lemon (C. volkameriana V Ten. & Pasq.), `Caipira` sweet orange + rough lemon (C. jambhiri Lush.), `Cleopatra` mandarin + `Volkamer` lemon, `Cleopatra` mandarin + sour orange (C. aurantium L.), `Rangpur` lime + `Sunki` mandarin (C. sunki (Hayata) hort. ex Tanaka), `Ruby Blood` sweet orange (C. sinensis L. Osbeck) + `Volkamer` lemon, `Rohde Red` sweet orange (C. sinensis L. Osbeck) + `Volkamer` lemon, and `Valencia` sweet orange + Fortunella obovata hort. ex Tanaka. For P. nicotianae trunk and root infection assays, plants of the somatic hybrids, obtained from 9-month semi-hardwood cuttings, were evaluated and compared with diploid citrus rootstock cultivars after mycelia inoculation in the trunk or spore infestation in the substrate, respectively. `Cleopatra` mandarin + sour orange, `Rangpur` lime + `Sunki` mandarin, `Cleopatra` mandarin + `Volkamer` lemon, `Ruby Blood` sweet orange + `Volkamer` lemon, `Rohde Red` sweet orange + `Volkamer` lemon, and `Caipira` sweet orange + `Volkamer` lemon had less trunk rot occurrence, whereas the somatic hybrids `Cleopatra` mandarin + `Volkamer` lemon, `Cleopatra` mandarin + sour orange, `Caipira` sweet orange + `Volkamer` lemon, and `Caipira` sweet orange + `Rangpur` lime were tolerant to root rot. For CTV assays, plants of the somatic hybrids along with tolerant and intolerant rootstocks were budded with a mild strain CTV-infected or healthy `Valencia` sweet orange budwood. Differences in average scion shoot length indicated that the hybrids `Cleopatra` mandarin + sour orange and `Valencia` sweet orange + Fortunella obovata were intolerant to CTV (c) 2007 Elsevier B.V. All rights reserved.

Absorption and Mobility of Boron in Young Citrus Plants

Boron (B) deficiency is widespread in Brazilian citrus orchards and has been considered an important soil constraint to citrus yield. The aim of this work was to study B uptake and its mobility in young citrus trees, under different B statuses, in two rootstocks. The experiment was carried out in a greenhouse, with `Valencia` sweet orange trees budded on Rangpur lime or Swingle citrumelo. The plants were grown in pots containing nutrient solutions under either adequate or deficient B supply. Plants with different B levels were transplanted into solution with adequate level of B, enriched in 10 B in different stages of development ( vegetative growth and fruiting). About 20 to 35% of B content in the new parts of orange tree came from plant reserves. Boron mobility within the plant was influenced by its nutritional status; that is, the longer the period was that the plants were grown under deficient supply, the smaller was the mobility. Boron concentration in the sweet orange trees on Swingle was higher than that on Rangpur, suggesting higher demand of swingle Citrumelo for B.

Acidity and Aluminum Speciation as Affected by Surface Liming in Tropical No-Till Soils

Aluminum toxicity is one of the major soil factors limiting root growth in acidic soils. Because of the increase in organic matter content in the upper few centimeters of soils under no-till systems (NTS), most Al in soil solution may be complexed to dissolved organic C (DOC), thus decreasing its bioavailability. The aim of this study was to evaluate the effects of surface liming on Al speciation in soil solution in Brazilian sites under NTS. Field experiments were performed in two regions with contrasting climates and levels of soil acidity: Rondonopolis, Mato Grosso State, on a Rhodic Haplustox, and Ponta Grossa, Parana State, on a Typic Hapludox. The treatments consisted of a control and three lime rates, surface applied to raise the base saturation to 50, 70, and 90%. Soil solution was obtained at soil water equilibrium (1:1 w/w soil/water ratio). The effects of surface liming on soil chemical attributes and on the composition of the soil solution were dependent on weather conditions, time under NTS, and soil weathering. Most Al in soil solution was complexed to DOC, representing about 70 to 80% of the total Al at pH <5.0, and about 30 to 4096 at pH >5.0. Under pH 5.5, the results were closely correlated with the solubility line for amorphous Al. Organic complexes may control Al(3+) release into soil solution at pH <5.5. Results suggest that in areas under NTS for a long period of time, Al toxicity might decrease due to its complexation to high-molecular-weight organic compounds.

Available Phosphorus Evaluated by Three Soil Tests in a Brazilian Tropical Oxisol Treated With Gypsum

Mehlich-1, resin-HCO(3), and Pi tests were used to assess available P in an acid tropical Oxisol in Brazil treated with gypsum, which has been preferred over lime to ameliorate the Al toxicity in the subsoil. The soil was incubated in the laboratory at rates up to 75 g kg(-1) of phosphogypsum (PG) containing 0.3% total P, natural gypsum, or reagent-grade gypsum, and up to 100 mg P kg(-1) as triple superphosphate (TSP) or phosphate rock (PR). In the greenhouse, two consecutive maize crops were grown on the soil treated with 50 mg P kg(-1) of TSP and PG rates up to 75 g kg(-1). The results of the incubation study showed that Mehlich-P and Pi-P increased with increasing PG rate for the treatments of TSP, PR, and control. Resin-HCO(3) underestimated available P from TSP and PR because of the reaction between resin-HCO(3) and gypsum. Mehlich-1 overestimated available P from PR compared with TSP because of an excessive dissolution of PR by the strongly acidic Mehlich-1. Pi underestimated available P from PR in the treatments of natural and reagent-grade gypsum because of Ca common-ion effect from gypsum on depressing PR dissolution. The results in terms of the effect of PG on available P are similar in both incubation and greenhouse studies. Both Mehlich-P and Pi-P correlated well with P uptake by maize, whereas resin-P did not.

Carbon and Nitrogen Dynamics in an Oxisol as Affected by Liming and Crop Residues under No-Till

The short-term effects of surface lime application and black oat (Avena strigosa Schreb.) residues, with or without N fertilization, were evaluated in a long-term no-till (NT) system on a sandy clay loam, a kaolinitic, thermic Typic Hapludox from the state of Parana, Brazil. The main plot treatments were: control and dolomitic lime applied on soil surface at 8 Mg ha(-1). Three treatments with crop residues were evaluated on the subplots: (i) fallow, (ii) black oat residues, and (iii) black oat residues aft er N fertilization at 180 kg ha(-1). Black oat dry biomass was not affected by the treatments during 3 yr. Surface liming increased soil pH, microbial biomass, microbial activity, and bacterial/fungal ratio at the soil surface (0-5 cm), resulting in increased amino acid turnover, water-soluble humic substances formation, and N mineralization and nitrification. While the application of black oat did increase the soil pH, overall it had much less effect on soil biological processes and C and N pools than did lime. We concluded that black oat cannot replace the need for lime to optimize crop production in these tropical NT systems. In the long term, however, black oat should aid in the amelioration of acidity and replenishment of soil organic C pools and should help reduce erosion. Overall, this study suggests that overapplication of inorganic fertilizer N may occur in some tropical NT systems. Further experiments are required in NT systems to investigate the use of slow-release N fertilizers in combination with lime and black oat as a mechanism to reduce acidification and promote sustainability.

Surface Liming and Zinc Availability in a Long-Term Experiment under No-Till System

No-till (NT) system with crop rotation is one of the most effective strategies to improve agricultural sustainability in tropical and subtropical regions. To control soil acidity in NT, lime is broadcast on the surface without incorporation. The increase in soil pH due to surface liming may decrease zinc (Zn) availability and its uptake by crops. A field experiment was performed in Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate Zn bioavailability in a NT system after surface liming and re-liming. Dolomitic lime was surface applied on the main plots in July 1993 at the rates of 0, 2, 4, and 6 Mg ha-1. In June 2000, the main plots were divided in two subplots to study of the effect of surface re-liming at the rates of 0 and 3 Mg ha-1. The cropping sequence was soybean [Glycine max (L.) Merrill] (2001-2 and 2002-3), wheat (Triticum aestivum L.) (2003), soybean (2003-4), corn (Zea mays L.) (2004-5), and soybean (2005-6). Soil samples were collected at the following depths: 0-0.05, 0.05-0.10, and 0.10-0.20m, 10 years after surface liming and 3 years after surface re-liming. Soil Zn levels were extracted by four extractants: (i) 0.005molL-1 diethylenetriaminepentaacetic acid (DTPA) + 0.1molL-1 triethanolamine (TEA) + 0.01molL-1 calcium chloride (CaCl2) solution at pH7.3 (DTPA-TEA), (ii) 0.1molL-1 hydrochloric acid (HCl) solution, (iii) Mehlich 1 solution, and (iv) Mehlich 3 solution. Zinc concentrations in leaves and grains of soybean, wheat, and corn were also determined. Soil pH (0.01molL-1 CaCl2 suspension) varied from 4.4 to 6.1, at the 0- to 0.05-m depth, from 4.2 to 5.3 at the 0.05- to 0.10-m depth, and from 4.2 to 4.8 at the 0.10- to 0.20-m depth, after liming and re-liming. Zinc concentrations evaluated by DTPA-TEA, 0.1molL-1 HCl, Mehlich 1, and Mehlich 3 solutions were not changed as a result of lime rate application. Re-liming increased Zn concentrations extracted by 0.1molL-1 HCl at 0-0.05m deep and by DTPA-TEA at 0.05-0.10m deep. Surface-applied lime promoted a decrease in Zn concentrations of the crops, mainly in grains, because of increased soil pH at the surface layers. Regardless of the liming treatments, levels of Zn were sufficient to soybean, wheat, and corn nutrition under NT.

Calcium: magnesium ratio in amendments of soil acidity: nutrition and initial development of corn plants in a Humic Alic Cambisol

The variation in the Ca:Mg ratio in amendments used to neutralize soil acidity is one way of altering the availability of those nutrients to the plants in acid soils. The objective of the work was to evaluate the effect of different proportions of calcium and magnesium in the form of CaCO(3) and MgCO(3) Oil the nutrient uptake, and initial production of dry matter by corn plants. The study was carried out in greenhouse conditions, in Lages, SC, with a completely randomized experimental design, with three replications. The treatments were the application of equivalent to 21.0 t ha(-1) of lime, using mixtures of CaCO(3) and MgCO(3) in several proportions to obtain different Ca:Mg ratios (1: 1, 2:1, 4:1, 8:1, 16:1 and 32:1), on a Humic Alic Cambisol, with 310 g kg(-1) of clay. The application of treatments caused the following Ca:Mg ratios in the CEC: 1. 1: 1, 2.1:1, 4.0:1, 8.1:1, 16.4:1 and 31.8:1. The high concentrations of exchangeable Ca in soil caused by addition of lime with high Ca content inhibited the uptake of Mg and K by the corn plants. The increase in the soil Ca:Mg ratio reduced the dry matter production and height of plants in the initial stage of development.

Rheological, mechanical and mucoadhesive properties of thermoresponsive, bioadhesive binary mixtures composed of poloxamer 407 and carbopol 974P designed as platforms for implantable drug delivery systems for use in the oral cavity

This study described the formulation and characterisation of the viscoelastic, mechanical and mucoadhesive properties of thermoresponsive, binary polymeric systems composed of poloxamer (P407) and poly(acrylic acid, C974P) that were designed for use as a drug delivery platform within the oral cavity. Monopolymeric and binary polymeric formulations were prepared containing 10, 15 and 20% (w/w) poloxamer (407) and 0.10-0.25% (w/w) poly(acrylic acid, 934P). The flow theological and viscoelastic properties of the formulations were determined using controlled stress and oscillatory rheometry, respectively, the latter as a function of temperature. The mechanical and mucoadhesive properties (namely the force required to break the bond between the formulation and a pre-hydrated mucin disc) were determined using compression and tensile analysis, respectively. Binary systems composed of 10% (w/w) P407 and C934P were elastoviscous, were easily deformed under stress and did not exhibit mucoadhesion. Formulations containing 15 or 20% (w/w) Pluronic P407 and C934P exhibited a sol-gel temperature T(sol/gel), were viscoelastic and offered high elasticity and resistance to deformation at 37 degrees C. Conversely these formulations were elastoviscous and easily deformed at temperatures below the sol-gel transition temperature. The sol-gel transition temperatures of systems containing 15% (w/w) P407 were unaffected by the presence of C934P; however, increasing the concentration of C934P decreased the T(sol/gel) in formulations containing 20%(w/w) P407. Rheological synergy between P407 and C934P at 37 degrees C was observed and was accredited to secondary interactions between these polymers, in addition to hydrophobic interactions between P407 micelles. Importantly, formulations composed of 20% (w/w) P407 and C934P exhibited pronounced mucoadhesive properties. The ease of administration (below the T(sol/gel)) in conjunction with the viscoelastic (notably high elasticity) and mucoadhesive properties (at body temperature) render the formulations composed of 20% (w/w) P407 and C934P as potentially useful platforms for mucoadhesive, controlled topical drug delivery within the oral cavity. (c) 2009 Published by Elsevier B.V.

Nuclear Quadrupole Resonance: A Technique to Control Hydration Processes in the Pharmaceutical Industry

Pharmaceuticals can exist in many solid forms, which can have different physical and chemical properties. These solid forms include polymorphs, solvates, amorphous, and hydrates. Particularly, hydration process can be quite common since pharmaceutical solids can be in contact with water during manufacturing process and can also be exposed to water during storage. In the present work, it is proved that NQR technique is capable of detecting different hydrated forms not only in the pure raw material but also in the final product (tablets), being in this way a useful technique for quality control. This technique was also used to study the dehydration process from pentahydrate to trihydrate.

Functionalisation of nanoparticles as electrolytes in fuel cells

Inorganic metal oxide materials are generally poor proton conductors as conductivities are lower than 10-5-10-6 S.cm-1. However, by functionalising Silica, Zirconia or Titania, proton conduction increases by up to 5 orders of magnitude. Hence, functionalised nanomaterials are becoming very competitive against conventional electrolyte materials such as Nafion. In this work, sol-gel processes are employed to produce silica phosphate, zirconia phosphate and titania phosphate functionalised nanoparticles. Furthermore, conductivities at hydrate conditions are investigated, and nanoparticle formation and functionalisation effects on proton conductivity are discussed. Results show conductivities up to 10-1 S.cm-1 (95% RH). Proton conduction increases with the functionalisation content, however heat treatment of nanoparticles locks the functionality in the crystal phase, thus inhibiting proton conduction. Controlling the mesopore phase allows for high proton conduction at hydrated conditions, clearly indicating facilitated ion transport through the pore channels.

The influence of joint position on the dynamics of perception-action coupling

Six right-handed subjects performed rhythmic flexion and extension movements of the index finger in time with an auditory metronome. On each block of trials, the wrist of the response hand was placed in a extended, neutral or flexed position. In the flex-on-the-beat condition, subjects were instructed to coordinate maximum excursion in the direction of finger flexion with each beat of the metronome. In the extend-on-the-beat condition, subjects were instructed to coordinate maximum excursion in the direction of finger extension with each beat of the metronome. The frequency of the metronome was increased from 2.00 Hz to 3.75 Hz in 8 steps (8 s epochs) of 0.25 Hz. During trials prepared in the extend-on-the-beat pattern, all subjects exhibited transitions to either a flex-on-the-beat pattern or to phase wandering as the frequency of pacing was increased. The time at which these transitions occurred was reliably influenced by the position of the wrist. Four subjects exhibited qualitative departures from the flex-on-the-beat pattern at pacing frequencies that were greater than those at which the extend-on-the-beat pattern could be maintained. The lime at which these departures occurred was not influenced by the position of the wrist. These results are discussed with reference to the constraints imposed on the coordination dynamics by the intrinsic properties of the neuromuscular-skeletal system.