Research Article
Non-destructive prediction of banana fruit quality using VIS/NIR spectroscopy
- Manuela Zude
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- Published online by Cambridge University Press:
- 15 April 2003, pp. 135-142
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Introduction. During ripening, the pigment content, starch index and sugar content of banana fruit change, providing accurate indicators for maturity classification. However, at present, banana fruits are traded according to their color stage. This study is aimed at investigating a non-destructive, rapid instrumental method to measure fruit maturity and quality more precisely. Materials and methods.Musa cavendishii L. grown in Honduras were ripened in a commercial ripening chamber and selected at four different color stages. Visible (VIS) and near-infrared spectroscopy (NIRS) in reflectance mode were investigated for the non-destructive detection of fruit chlorophyll and sugar contents. Partial least squares regression was applied to auto-scaled spectral data. Reference analyses were performed using spectrophotometry after a diethyl ether extraction of chlorophyll and high performance liquid chromatography for individual sugar analysis. Results. Calibration models for spectral readings and laboratory destructive tests gave multivariate correlation coefficients of determination of $R^2 > 0.70$ for chlorophyll a, R2 = 0.96 with standard errors of calibration (scal) of 1.6, and standard errors of cross-validation (scval) of 1.8 for glucose; R2 = 0.94 with scal of 0.8, and scval of 0.9 for sucrose; R2 = 0.96 with scval of 2.5 and Scval of 2.7 for fructose (g$\cdot$kg-1 on a dry weight basis). Conclusion. This paper shows the potential of VIS/NIRS for non-destructively predicting the maturity and quality of whole banana fruit based on determining fruit chlorophyll and sugar contents.
Effet de la cercosporiose à Phaeoramularia angolensis sur la teneur et la composition chimique des huiles essentielles de peau d'orange
- Jean Kuate, Pierre Michel Jazet-Dongmo, Daniel Ducelier, François Damesse, Chantal Menut, Jean Marie Bessière
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- 15 April 2003, pp. 143-149
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Introduction. Les dommages provoqués par la cercosporiose des agrumes, dus à Phaeoramularia angolensis, sont à l'origine de pertes de récolte ou d'écarts de tri pouvant varier entre (50 et 100) % de la production. Or tous les organes attaqués par la maladie - pétales des fleurs, feuilles et surtout peau des fruits - renferment des huiles essentielles à haute valeur marchande. Une étude a été réalisée pour connaître l'influence des attaques de cette maladie sur le rendement d'extraction et la qualité des huiles essentielles de peau d'orange. Matériels et méthodes. L'extraction d'huile essentielle a été réalisée par hydrodistillation à partir de fruits récoltés à maturité et les extraits ont été analysés par chromatographie en phase gazeuse afin de déterminer leur composition chimique. Résultats et discussion. Le rendement d'extraction des huiles essentielles a diminué en fonction de la gravité des attaques (jusqu'à 40 % de baisse). Cette baisse n'a été significative que lorsque les attaques dépassaient deux lésions par fruit. Les extraits obtenus de fruits attaqués à divers degrés ont présenté quelques variations quantitatives de leurs constituants. Une diminution de certains composés dans les fruits malades s'est accompagnée d'une augmentation de leur forme oxygénée. L'augmentation de la quantité globale d'aldéhydes a été observée dans les fruits malades, ce qui pourrait se traduire par une amélioration de la qualité des huiles essentielles. Mais, en même temps, les oxydes caractéristiques de la dégradation de ces huiles essentielles ont augmenté. Conclusion. Ce travail qui doit être approfondi a permis d'acquérir de premières données sur les pertes de rendement et l'évolution de la composition des huiles essentielles de peau de fruits pouvant être attribuées aux attaques de la cercosporiose.
`Tahiti' lime fruit set related to gibberellic acid application on out-of-season flowering and the accumulation of degree days
- Bellato Spósito Marcel, de Assis Alves Mourão Filho Francisco
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- Published online by Cambridge University Press:
- 15 April 2003, pp. 151-156
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Introduction. The production of `Tahiti' limes in southern Brazil has increased in the last 20 years and has become a good alternative for citrus growers in regions where Citrus Variegated Chlorosis has affected sweet orange groves. One of the main goals to insure success in growing `Tahiti' limes is to apply the right techniques to induce out-of-season flowering and winter fruit harvest when the fruit prices are the highest. This experiment evaluated the effects of gibberellic acid application on fruit set of `Tahiti' lime trees related to out-of-season flowering and accumulated degree days. Materials and methods. Eight-year-old plants were treated with five concentrations of gibberellic acid [ (0, 10, 25, 50 and 100) mg$\cdot$L-1] applied during anthesis of out-of-season bloom. Accumulation of degree days for fruit set and fruit development in the conditions of São Paulo State, Brazil, were calculated. The percentage of fruit set determined by weekly counts of the number of flowers from anthesis to the maturation of the fruits were determined on each previously marked branch. Data were submitted to regression analysis. Results and discussion. In regard to fruit set, it was observed that 10 mg gibberellic acid$\cdot$L-1 was enough to retain more than 10% of fruits in relation to the number of formed flowers. Starting from anthesis, (837.7 and 1 115.2) accumulated degree days were necessary for the stabilization of the fruit set and fruit maturation, respectively.
Pollination requirements of loquat (Eriobotrya japonica Lindl.), cv. `Algerie'
- Julián Cuevas, Juan José Hueso, Moisés Puertas
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- 15 April 2003, pp. 157-165
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Introduction. Loquat shares with other pomes, such as apple (Malus domestica) and pear (Pyrus communis), flowering habits, but, in contrast with them, the tree is considered a self-compatible species. However, when planted in solid blocks under mesh, low fruit set and small fruit size are often reported. To explore in which way restrictions of bee activity and/or impediments for cross-pollination can be responsible for low productivity and poor fruit quality, we carried out controlled pollination on flowers of loquat cv. Algerie. Materials and methods. A first experiment checked cross-pollination response by comparing fruit set and quality from self-, open-, and cross-pollinated flowers. A second experiment explored poor pollination effects by modifying the number of stigmas being hand cross-pollinated. Results. Cv. Algerie loquat flowers cross-pollinated with pollen of cvs. `Tanaka' and `Golden Nugget' loquat flowers produced more fruits of higher quality (larger, heavier and more precocious) than flowers under self-pollination. Benefits of cross-pollination can be explained by an earlier and higher level of fertilization. Observations under microscopy showed, however, that self-incompatibility of cv. Algerie flowers is not complete, and a certain level of self-fertilization occurs. The second experiment demonstrated that limiting the number of stigmas pollinated resulted in a significant reduction in the number of seeds formed that, in turn, affected fruit size and shape. Flowers with only one stigma pollinated seldom formed more than two seeds while flowers with all five stigmas pollinated produced fruit with an average of four seeds. Conclusion. Our results emphasize a dependence of cv. Algerie flower pollination on both adequate activity of pollinator insects and appropriate placement of pollinizers.
Effets du milieu de culture et de la lumière sur l'embryogenèse somatique de l'olivier (Olea europaea L.) cv. Picholine marocaine
- Najiba Brhadda, Abdelhadi Abousalim, Loudyi Dou Elmacane Walali
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- 15 April 2003, pp. 167-174
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Introduction. Jusqu'à présent, aucun protocole n'a été développé pour l'embryogenèse somatique de l'olivier Picholine, cultivar exploité dans près de 98 % des plantations d'oliviers au Maroc. Nos travaux ont donc cherché à étudier les effets de la composition du milieu de culture et de la lumière sur l'induction et le développement d'embryons somatiques chez ce cultivar. Matériel et méthodes. Après désinfection des noyaux d'olives Picholine, des cotylédons ont été mis en culture après suppression des embryons zygotiques. Ils ont été disposés en boîtes de Pétri soit entiers, soit en distinguant les parties proximales et distales. Pour la phase d'induction de cals embryogènes, quatre milieux de base [Murashige et Skoog (MS), Bourgin et Nitsch (BN), Schenk et Hildebrandt (SH) et Canas et Benbadis (OMc)], additionnés de régulateurs de croissance (zéatine et ANA), ont été testés soit à l'obscurité, soit en photopériode de 16 h. Après 6 semaines de culture sur ces milieux d'induction, les cals ont été transférés en tubes, dans des milieux de culture frais mais sans ANA et soumis à une photopériode de 16 h. À l'issue de cette phase, les plantules présentant des racines bien développées et au moins deux feuilles ont été repiquées dans des pots contenant un substrat et acclimatées en serre. Résultats. Les meilleurs résultats d'induction et de développement des embryons somatiques ont été obtenus avec le milieu MS et aucune morphogenèse n'a été observée sur le milieu OMc. L'incubation à la lumière a significativement réduit l'induction des cals embryogènes et a inhibé la régénération des plantules. Les parties proximales des cotylédons ont donné de meilleurs résultats que les parties distales. Le taux de régénération de plantules a atteint 40 % des explants mis en culture et le pourcentage de survie obtenu après leur acclimatation a atteint 94 %. Conclusion. Le protocole décrit a démontré la capacité embryogène du cultivar Picholine marocaine. Il pourra être exploité pour la propagation de cet olivier au Maroc.
In vitro clonal mass propagation of Ximenia americana L.
- Magdi Ahmed Ibrahim Aloufa, Sandra M.L. Bezerra, Gyselle P.T. Jordâo
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- 15 April 2003, pp. 175-178
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Introduction.Ximenia americana is a species developed in Africa and South America. This fruit tree is threatened by a dangerous process of genetic erosion. In vitro techniques could be used for its rapid clonal propagation. Since there is still no report on vitroculture of the species, we tested its micropropagation using axillary buds from mature plants of X. americana. Materials and methods. Single node explants of X. americana shoots were cultured on a proliferation medium made up with a MS medium containing different concentrations (2.5-15 μM) of two cytokinins [benzyladenine (BA) or kinetin] used individually or in combination with 0.5 μM of an auxin [2,4-dichlorophenoxyacetic acid (2,4-D) or naphtaleneacetic acid (NAA)]. Data were recorded after 5 weeks of culture. From proliferated shoot clumps, shoot explants (approximately 3 cm in length) were excised and transferred to rooting media made up with MS medium with or without 0.5 M of indolebutyric acid (IBA) (pH = 5.8). Results. The most rapid and earliest proliferation was observed in media with the lowest concentrations of cytokinins. Absence of growth regulators in media and media with 2,4-D or NAA considerably delayed bud proliferation. The number of shoots per explant increased with the increase of cytokinins. The maximum number of shoots was achieved in 10 μM BA. When shoots were transferred to rooting media, media supplemented with 0.5 μM IBA improved the rooting frequency, root quality and number of roots per cutting. After rooting, the vitroplants were transplanted into small polybags with 1:1 non-sterile soil and sand, then in the field after 4 weeks. Eighty percent of the plants taken from regulator-supplemented media were acclimated versus 15% of those taken from auxin-free media. Conclusion. The rapid clonal propagation of X. americana is possible through in vitro culture of nodal explants. The best cytokinin for shoot multiplication was BA.