Control endógeno y exógeno de la maduración externa de los frutos cítricos

En esta Tesis Doctoral se estudió el proceso de regulación de la maduración externa de los frutos cítricos, con el objetivo de determinar los factores endógenos y exógenos que lo afectan. Los factores hormonales y nutricionales implicados en el proceso, se estudiaron: a) en cultivares de naranjos y mandarinos de maduración temprana, intermedia y tardía, y b) modificando el proceso en etapas próximas al cambio de color, mediante aplicaciones de reguladores de crecimiento y sustancias nitrogenadas, o interrumpiendo la conexión floemática entre el fruto y la planta (anillado de pedúnculo). El estudio de los factores exógenos (temperatura del aire y del suelo) se realizó en mandarinos de maduración temprana, a través de la disminución de la temperatura radicular cubriendo el suelo con mallas o cal, y su asociación con la temperatura del aire. Las principales conclusiones resultantes de este trabajo fueron: - Las giberelinas GA1 y GA4 deben exportarse desde el flavedo de los frutos para permitir el cambioa de color. - La aplicación de GA3 no solo retarda la pérdida de clorofilas, sino que reduce la concentración de pigmentos carotenoides coloreados (&-criptoxantina, cisviolaxantina y &-citraurina) y aumenta la de pigmentos propios de los frutos verdes (&-caroteno y luteína) a lo largo de todo el período de maduración. - Con el cambio de color se incrementa la concentración de ABA en el flavedo, pero éste no es el de promotor del proceso. - Se verifica una relación inversa entre el color y la concentración de nitrógeno en el flavedo en condiciones in vivo. Las evidencias de que el incremento de GAs es, por una parte, la señal endógena primaria que limita el cambio de color y promueve, por otra, el incremento del N endógeno, permiten postular un papel subsidiario de éste en el proceso de la maduración externa de los frutos cítricos.Gambetta Romaso, MG. (2009). Control endógeno y exógeno de la maduración externa de los frutos cítricos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7584Palanci

Tree water status influences fruit splitting in Citrus

[EN] Fruit splitting or cracking is a major physiological disorder in fruit trees markedly influenced by environmental conditions, but conclusive data still are required to provide a definite explanation and preventive measures. Changes in climatic conditions critically influence fruit splitting incidence. We studied plant-soil-ambient water relations in splitting-prone citrus grown under 4 contrasting environmental conditions (climate type and soil), in Spain and Uruguay, over a six years period. Automatic trunk and fruit diameter measurements (trunk and fruit growth rate and maximum daily trunk shrinkage), which are a tree water status indicator, together with factors modifying the tree and fruit water relationship (temperature, ET, rainfall, soil texture, soil moisture, rootstock and xylem anatomy) were studied and correlated with splitting. A close fruit splitting and soil texture relationship was found, inversely correlated with clay and silt percentages, and positively with those for sand. Under 85%-sand soil conditions, slight changes in soil moisture due to fluctuations in temperature, ET, or rainfall changed trunk and fruit growth rate patterns during few hours and induced splitting. Splitting incidence was higher in trees with larger xylem vessels in the fruit peduncle due to rootstock ('Carrizo' and 'C-35' citrange being higher than 'FA-5', 'Cleopatra' and Poncirus trifoliata). Finally, reducing the frequency of irrigation by half increased midday canopy temperatures (similar to 5 degrees C) and splitting (+15%). We conclude that irregularities in the tree water status, due to interactions among soil moisture, rootstock and climatic conditions, leads to a number of substantial changes in fruit growth rate increasing the incidence of fruit splitting. (C) 2016 Elsevier B.V. All rights reserved.Mesejo Conejos, C.; Reig Valor, C.; Martinez Fuentes, A.; Gambetta, G.; Gravina Telechea, A.; Agustí Fonfría, M. (2016). Tree water status influences fruit splitting in Citrus. Scientia Horticulturae. 209:96-104. doi:10.1016/j.scienta.2016.06.009S9610420

Hydrated Lime Soil Coverage: Effect On Soil Temperature Reduction And Early Mandarin Colour Break

[EN] Citrus fruit colour is an important marketing feature. In view of the relative independence between internal and external maturity, in early mandarins fruit harvest takes place before reaching fruit full colouration. Since citrus fruit colour break is associated to natural temperature reduction, this work evaluated the efficiency of hydrated lime soil coverage on the advance of fruit colour break of Satsuma and Clementine. Experiments were carried out in Spain (Satsuma 'Iwasaki' and Clementina 'Clemenpons', grafted on citrange 'Carrizo') and in Uruguay (Satsuma 'Okitsu' and 'Clementina de Nules', grafted on P. trifoliata). Hydrated lime was applied between two and four months before harvest. Treatment diminished soil temperature between 0.5 °C and 3 °C in all situations. In Satsuma, treatment could not advance colour break, since soil temperature remained above 23 °C and 18 °C, thresholds below which root metabolism of citrange 'Carrizo' and P. trifoliata, respectively, is reduced. In Clementine, maturing two months later, the soil temperature remained below thresholds during at least one month before harvest, significantly advancing fruit colour break and increasing the percentage of fruit harvested early[ES] El color de los frutos cítricos es una característica importante para su comercialización. En la medida en que la maduración interna y externa presentan una regulación relativamente independiente, en las mandarinas precoces la cosecha de los frutos se realiza sin haber alcanzado la coloración adecuada para su comercialización. Considerando que el cambio de color de los frutos cítricos se asocia a la disminución de la temperatura, en este trabajo se evaluó la eficacia de la cobertura del suelo con cal en el adelanto del cambio de color de mandarinas Satsuma y Clementina. Los experimentos se realizaron en España (Satsuma 'Iwasaki' y Clementina 'Clemenpons', injertados sobre citrange 'Carrizo') y en Uruguay (Satsuma 'Okitsu' y 'Clementina de Nules', injertados sobre P. trifoliata). La cal se aplicó entre los dos y cuatro meses previos a la cosecha. El tratamiento disminuyó la temperatura del suelo entre 0,5 °C y 3 °C en todas las situaciones. En Satsuma el tratamiento no logró anticipar el cambio de color, ya que la temperatura del suelo permaneció por encima de 23 °C y 18 °C, umbrales por debajo de los cuales disminuye la actividad de las raíces de citrange 'Carrizo' y P. trifoliata. En Clementina, que madura dos meses más tarde, la temperatura del suelo permaneció por debajo de los umbrales durante por lo menos un mes antes de la cosecha, adelantando significativamente la coloración de los frutos y permitiendo incrementar el porcentaje cosechado en forma temprana.A las empresas Agrimarba S.A. (España), Frutícola Libertad S.A., El Repecho, S.A. y Antonio De Souza e hijos (Uruguay). Trabajo parcialmente financiado por el Programa ALßan, becas de alto nivel de la Unión Europea para América Latina (NI E03D15012UR) y la Comisión Sectorial de Investigación Científica (Universidad de la República, Uruguay).Gambetta Romaso, G.; Mesejo Conejos, C.; Gravina Telechea, A.; Agustí Fonfría, M.; Fasiolo, C.; Rey, F.; Reig Valor, C.... (2015). Cobertura del suelo con cal: efecto de la reducción de la temperatura y cambio de color de las mandarinas precoces. Agrociencia. 19(1):31-40. http://hdl.handle.net/10251/73903S314019

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Key determinants of citrus fruit quality: Metabolites and main changes during maturation

Citrus is one of the main fruit crops in the world and widely recognized by their organoleptic, nutritional and health-related properties of both fresh fruit and juice. The genetic diversity among the genus and the autonomous and independent changes in peel and pulp, make the definition of standard maturity indexes of fruit quality difficult. Commercial maturity indexes in the citrus industry are usually based on peel coloration, percentage of juice, soluble solids/acidity ratio but their relevance may differ among varieties and the specific requirements of the markets. There is also a marked influence of environmental and agronomic conditions such as light and temperature, rootstock selection and plant nutrition, among others. Besides commercial requirements, a more comprehensive definition of fruit quality should also consider organoleptic and nutritional properties that are determined by a complex interaction among a number of bioactive components. Citrus fruit are an excellent source of many phytochemical, including ascorbic acid, carotenoids (antioxidant and pro-vitamin A), polyphenols, flavonoids, limonoids, terpenoids, etc., which greatly contribute to the health-related benefits of these fruits. Criteria and definition of the main maturity indexes for citrus fruit worldwide are described, as well as changes during fruit maturation in key components affecting organoleptic and nutritional properties. Moreover, the involvement of hormonal and nutritional signals and their interaction in the regulation of external and internal maturation of citrus fruit, as well as the influence of environmental and agronomic factors are also critically revised and discussed.The financial support of the research grants AGL-2015-70218R (Ministerio de Economia, Industria y Competitividad, Spain) and PROMETEOII 2014/27 (Generalitat Valenciana) is gratefully acknowledged.Peer reviewe

Transcriptional Analysis of C-Repeat Binding Factors in Fruit of Citrus Species with Differential Sensitivity to Chilling Injury during Postharvest Storage

Citrus fruit are sensitive to chilling injury (CI) during cold storage, a peel disorder that causes economic losses. C-repeat binding factors (CBFs) are related to cold acclimation and tolerance in different plants. To explore the role of Citrus CBFs in fruit response to cold, an in silico study was performed, revealing three genes (CBF1, CBF2, and CBF3) whose expression in CI sensitive and tolerant cultivars was followed. Major changes occurred at the early stages of cold exposure (1–5 d). Interestingly, CBF1 was the most stimulated gene in the peel of CI-tolerant cultivars (Lisbon lemon, Star Ruby grapefruit, and Navelina orange), remaining unaltered in sensitive cultivars (Meyer lemon, Marsh grapefruit, and Salustiana orange). Results suggest a positive association of CBF1 expression with cold tolerance in Citrus cultivars (except for mandarins), whereas the expression of CBF2 or CBF3 genes did not reveal a clear relationship with the susceptibility to CI. Light avoidance during fruit growth reduced postharvest CI in most sensitive cultivars, associated with a rapid and transient enhance in the expression of the three CBFs. Results suggest that CBFs-dependent pathways mediate at least part of the cold tolerance responses in sensitive Citrus, indicating that CBF1 participates in the natural tolerance to CI.This work was supported by a research grant from the National Agency of Research and Innovation (ANII-Uruguay) by the code FCE_3_2016_1_126714 and by a research grant RTI2018–095131-B-I00 of the Ministry of Science and Innovation (Spanish Government). F. Rey is the recipient of a predoctoral scholarship (POS_EXT_2016_1_133720) from ANII (Uruguay).Peer reviewe

Relationship between soil temperature and fruit colour development of Clemenpons Clementine mandarin (Citrus clementina Hort ex. Tan)

[EN] BACKGROUND: In Citrus, root temperature regulates rind colouration. However, few studies have investigated the range of temperatures and timing which determine rind colour break. The objective of this study was to determine the relationship between range of soil temperature (ST) and rind colour development in the precocious ‘Clemenpons’ Clementine mandarin. Reflective white plastic mulch was used to modify root temperature. RESULTS: Mulching increased reflected light and reduced daily maximum ST and temperature range, major differences being established 70–30 days before harvest. Rind colour-break correlated positively with 20 "C<ST<23 "C; thus, 20–23 "C appears to be the ST threshold interval for fruit colouration. The sooner the soil reached it, the sooner the fruit changed rind colour. In our experiments, control trees accumulated 565 h at this ST interval before fruit changed colour, whereas in treated trees it occurred 2 weeks earlier. Hence, in treated trees the colour break was advanced by 2 weeks and this increased the percentage of fruit harvested at the first picking date by up to 2.5-fold. CONCLUSIONS: Fruit colour-break does not take place at a certain ST, but after several hours at a ST of 20–23 "C. In our experiments, reducing ST during the 2months before harvest advances the first picking date in the ‘Clemenpons’ Clementine mandarin.Mesejo Conejos, C.; Gambetta Romaso, G.; Gravina Telechea, A.; Martinez Fuentes, A.; Reig Valor, C.; Agustí Fonfría, M. (2012). Relationship between soil temperature and fruit colour development of Clemenpons Clementine mandarin (Citrus clementina Hort ex. Tan). Journal of the Science of Food and Agriculture. 92:520-525. doi:10.1002/jsfa.4600S5205259

Gibberellic acid and norflurazon affecting the time-course of flavedo pigment and abscisic acid content in Valencia sweet orange

In Citrus, colour break has been positively related to ethylene, abscisic acid (ABA) and carbohydrates, and negatively related to gibberellins and nitrogen. However, the mechanisms by which these substances affect the process are not well understood. This study analyses the role of gibberellins and ABA, through gibberellic acid (GA(3)) and norflurazon (NFZ) applications, on the evolution of flavedo pigments in on-tree degreening and regreening 'Valencia' sweet orange fruit. In two experiments, 180 fruits were tagged previous to colour break, 60 were treated with NFZ, another 60 with GA(3), and the remaining 60 were used as control. In control fruit, flayed ABA concentration increased as did colour development, declining just before full colour developed. NFZ did not affect chlorophyll degradation, but provoked a partial blockage of the carotenoid biosynthesis pathway increasing phytoene and phytofluene concentrations in the flavedo. As a consequence, flavedo ABA concentration temporarily reduced as did fruit colour intensity, but it did not delay the onset of colour break. Conversely, GA(3) delayed flavedo chlorophyll degradation and reduced beta-cryptoxanthin and beta-citraurin biosynthesis, and, thus, delayed fruit colour break. GA(3)-treated fruit also accumulated higher lutein and beta-carotene concentrations, but remained greener than control fruit, and reduced flavedo ABA concentration, but not significantly. Ethylene was not detected, in any treatment. Our results confirm that ABA concentration paralleled colour development, but it did not trigger the process. (C) 2014 Elsevier B.V. All rights reserved.Gambetta Romaso, MG.; Mesejo Conejos, C.; Martinez Fuentes, A.; Reig Valor, C.; Gravina Telechea, A.; Agustí Fonfría, M. (2014). Gibberellic acid and norflurazon affecting the time-course of flavedo pigment and abscisic acid content in Valencia sweet orange. Scientia Horticulturae. 180:94-101. doi:10.1016/j.scienta.2014.10.021S9410118