BUSCADOR RECOLECTA

[ES] La principal variedad de peral cultivada en España, ‘Agua de Aranjuez’, se caracteriza por una marcada tendencia a los cuajados erráticos. A consecuencia de esto y con el fin de estabilizar producciones, la aplicación de ácido giberélico para la inducción de frutos partenocárpicos se ha convertido en una práctica generalizada. La creciente preocupación por la regularización de hormonas de síntesis en fruticultura puede poner en riesgo la producción de este cultivar. El mal comportamiento productivo de ‘Agua de Aranjuez’, se ha intentado explicar sobre la base de numerosas hipótesis. En este artículo revisamos los últimos resultados obtenidos en este cultivar, determinando la importancia relativa de diferentes factores reproductivos que contribuyen a explicar los cuajados erráticos. En base a estos resultados se propone una alternativa agronómica a su actual sistema de producción, basada en el establecimiento de unas adecuadas condiciones de polinización., [EN]‘Agua de Aranjuez’ pear is a cultivar particularly prone to erratic fruit set. This has been overcome through the induction of parthenocarpic fruits following treatment with gibberelic acid, to the point that the production of this cultivar relies on this treatment. However, recent concern on the use of hormonal products in fruit crops, may jeopardize the production of this cultivar. The poor cropping performance of ‘Agua de Aranjuez’ has been explained under a number of hypotheses. In this work we review the last results obtained in this cultivar, determining the relative importance of different reproductive factors contributing to erratic fruit set. Based on these results a pollination alternative for the production of this cultivar is discussed., Este trabajo ha sido financiado por los proyectos INIA RTA01-103, CICYT AGL 2003-05318 y Grupo de Investigación Consolidado DGA A02, A-43., Peer reviewed

Most pear (Pyrus communis L.) cultivars are impaired to set fruit under self-pollination, because self-fertilization is prevented by a gametophytic self-incompatibility system. However, accumulated information in this species shows that often for a same cultivar, after self-pollination, a variable response in fruit set can be obtained in different years or growing conditions. In this work, we characterize self-incompatibility and self-fruitfulness in 'Agua de Aranjuez', the main Spanish pear cultivar, which also shows a variable response to self-pollination. Two years with a different fruit setting response after self-pollination, one with no fruit set and the other with a moderate fruit set, were compared for parthenocarpic fruit development and for pollen tube performance. Results show that in both years, this cultivar behaves as self-incompatible with absence of parthenocarpy. In selfed flowers, most pollen tubes are arrested in the upper half of the style, although in a small proportion of the styles, a pollen tube can reach the base of the style and eventually effect fertilization. Self-fertilization, although occurring at a low level, can explain the fruit set levels obtained under self-pollination given that flowers with just one fertilized ovule are able to set fruit. This behavior could explain confusing results about self-fruitfulness in 'Agua de Aranjuez' and other pear cultivars., Peer reviewed

Apples and pears are fruit crops particularly susceptible to cropping irregularities. A strong relationship has been observed between the effective pollination period (EPP) and the general cropping of the orchard. The EPP concept has also been proven to be a useful parameter to establish a relationship between the variation in the reproductive process and cropping behaviors. For apples and pears, a slow pollen tube growth has been shown to be the main limiting factor of the EPP in the traditional cooler temperate cultivation regions. However, while higher temperatures speed up the pollen tube growth, the expansion of these crops into warmer areas often results in failures of fruit set. Thus, with the aim to ascertain the main limiting factor responsible for fruit set failures in Mediterranean conditions we have evaluated the EPP for two consecutive years in 'Agua de Aranjuez' pear, the main Spanish cultivar, by studying the stigmatic receptivity, pollen tube kinetics, and ovule development. Complete flower fertility was maintained for just 2 days after anthesis in both years. Pollen tube kinetics and ovule degeneration do not appear to limit flower receptivity. However, the stigmatic receptivity expressed as flowers with at least one receptive stigma, closely matches the duration of the EPP evaluated from fruit set experiments. This was consistent over the 2 years of experiments, in spite of the differences recorded in the EPP, suggesting that stigmatic receptivity is clearly the limiting factor of flower receptivity. This is the first report for stigmatic receptivity limiting the EPP in pears and suggests that stigmatic receptivity could be an important factor limiting pear flower receptivity and hence cropping performance under warmer conditions., Peer reviewed

[EN] Onset of bearing and cropping during the first five productive years of twenty clones (ten trees each) of the pear variety "Agua de Aranjuez" have been studied. Annual yields varied in space and time considerably. Within the same elemental unit, tree error was very often higher than replicates of the same clon and among different ones. Cropping differences accounted of either irregular blossom production or uneven fruit set, the latter being influenced by distance from pollinators, temperature at blossom time and flower esterility produced by drought at fruit bud differentiation and flower development. In spite of the various causes which have created such irregularity of cropping, differences on productivity between clones are shown, and several among the most productive have been chosen., [ES] Se estudia la entrada en producción y la cosecha durante los cinco primeros años productivos en una plantación de 200 árboles de la variedad Agua de Aranjuez conteniendo 20 clones de dicha variedad. Las cosechas anuales registradas presentaron considerable variación en el espacio y en el tiempo. Frecuentemente la variación entre árboles de una misma parcela elemental fue superior a la presentada por repeticiones de un mismo clon y a la presentada por clones diferentes. Las diferencias en cosecha han sido producidas, en unos casos, por diferencias en cantidad de flor, y en otros, por desigual cuajado de fruto. A su vez, en el desigual cuajado de fruto han influído la distancia al polinizador, las temperaturas durante la floración, y la esterilidad femenina producida por la sequía durante el período de diferenciación y desarrollo de las yemas de flor. No obstante, la diversidad de causas que han producido variaciones en la producción, se ha podido comprobar que existen diferencias en productividad entre clones, y se han retenido algunos clones de mejor productividad., Peer reviewed

5 Pags.- 2 Figs.- 2 Fots., En este trabajo se lleva a cabo una selección de polinízadores para el cultivar Agua de Aranjuez. Para ello se ha determinado por una parte las épocas de floración, seleccionando 17 cultivares de floración temprana y coincidentes con Agua de Aranjuez. Paralelamente se han determinado las relaciones de inter-compatibilidad con éste., Este trabajo ha sido financiado por los Proyectos INIA SC 98-049 y RTA 01-103. Beca predoctoral INIA a J.S., Peer reviewed

Peer reviewed