Erratic fruit set in almond under warm climates

The cause for the erratic yields of the two main almond cultivars grown in Morocco has been searched in order to recommendpossible solutions for a high and stable production. The lack of sufficient bloom overlap between ‘Marcona’ and ‘Fournat de Brézenaud’in many years may be one of the reasons of this erratic behavior, but not the only one, as the same behaviour may be observed in twosimultaneously blooming cultivars, ‘Ferragnès’ and ‘Ferraduel’. The relatively high temperatures observed during the blooming periodsignificantly reduced the stigma receptivity of these cultivars and, as a consequence, their effective pollination period, showing that stigmaticreceptivity is a limiting factor for fruit set in ‘Marcona’ and ‘Ferragnès’ and their subsequent yield reduction under warm conditions. Thus, inthe present context of global warming, the search for cultivars tolerant to heat stress during flowering will acquire a special interest, as wellas the combination of cultivars with the same chilling and heat requirements to ensure a simultaneous bloom

Erratic fruit set in almond under warm climates

The cause for the erratic yields of the two main almond cultivars grown in Morocco has been searched in order to recommend possible solutions for a high and stable production. The lack of sufficient bloom overlap between ‘Marcona’ and ‘Fournat de Brézenaud’ in many years may be one of the reasons of this erratic behavior, but not the only one, as the same behaviour may be observed in two simultaneously blooming cultivars, ‘Ferragnès’ and ‘Ferraduel’. The relatively high temperatures observed during the blooming periodsignificantly reduced the stigma receptivity of these cultivars and, as a consequence, their effective pollination period, showing that stigmatic receptivity is a limiting factor for fruit set in ‘Marcona’ and ‘Ferragnès’ and their subsequent yield reduction under warm conditions. Thus, in the present context of global warming, the search for cultivars tolerant to heat stress during flowering will acquire a special interest, as well as the combination of cultivars with the same chilling and heat requirements to ensure a simultaneous bloom

Comunicación corta. Exportación de los macroelementos mayoritarios por los frutos de diferentes cultivares de almendro

The amount of the major macroelements required to produce a given crop has been determined for a set of 11 almond (Prunus amygdalus Batsch) cultivars growing in the Middle Ebro Valley (NE Spain). A wide diversity of nutrient exports was found among the different cultivars. Although the production of kernels is the main objective when growing almonds, all the different fruit components: the mesocarp (hull), the endocarp (shell) and the seed (kernel), were taken into account. The different fruit components showed a great variation among cultivars, and the amount of fruit dry matter required for producing 1 kg of kernel ranged from 4.32 kg in ‘Guara’ to 10.56 kg in ‘Desmayo Largueta’. Similarly, the macroelement requirements to produce a given amount of kernels varied among the different cultivars. ‘Guara’ has proved to be the most effective cultivar in taking advantage of the mineral elements for producing a crop, showing that this efficiency is independent of the shell type. Se determinó la cantidad de macroelementos mayoritarios necesarios para producir una determinada cantidad de cosecha en un grupo de 11 cultivares de almendro (Prunus amygdalus Batsch) cultivados en el Valle Medio del Ebro (NE de España). Se encontró una gran diversidad de requerimientos entre los diferentes cultivares. Aunque la producción de pepitas es el objetivo principal en el cultivo del almendro, todos los componentes del fruto se han de tener en cuenta en este cálculo: el mesocarpo (la piel), el endocarpo (la cáscara) y la semilla (la pepita). Estos tres componentes del fruto mostraron una gran variabilidad entre los cultivares y la cantidad de materia seca necesaria para producir 1 kg de pepita osciló entre 4,32 kg en ‘Guara’ y 10,56 kg en ‘Desmayo Largueta’. Igualmente, los requisitos en macroelementos para producir una cantidad determinada de pepita varió entre los diferentes cultivares. ‘Guara’ mostró ser el cultivar más eficiente en la utilización de los elementos minerales para la producción de una cosecha, mostrando que esta eficiencia es independiente del tipo de cáscara

Genetic analysis for physical nut traits in almond

Peer ReviewedPublishe

Physical Fruit Traits in Moroccan Almond Seedlings: Quality Aspects and Post-Harvest Uses

The physical traits of local almond populations from Morocco were studied to characterize their genetic resources and to evaluate the possibility of their commercial valorization. Nut weight ranged between 1.15 and 7.39 g, and kernel weight between 0.54 and 1.85 g, but most accessions were characterized by small kernels, pronounced wrinkles, and double kernels. Although the physical quality of the kernels of these populations was low, they show the possibility of some specialized uses, which could improve their marketable value. The genotypes with favorable values could be incorporated into an almond breeding program as parents to increase the kernel quality.Publishe

Peculiaritats al·lèliques del locus S de les cultivars mallorquines d’ametller

The examination of the allelic diversity of the locus S in ten almond cultivars from Majorca has shown the presence of the Sf allele in four of them, as well as the presence of five new alleles non identified so far. Although the Sf allele has been described as responsible for the expression of self-compatibility in almond, it has been recently shown that this allele has two different phenotypic expressions. As a consequence, this allele cannot be always considered an index for self-compatibility of the genotypes harbouring it. The study of the four Majorcan cultivars possessing this allele has confirmed their selfincompatibility, showing that this allele is in its phenotypically active form, as it has been also observed in a group of cultivars from southern Italy, a fact possibly suggesting a connexion between these two Mediterranean almond populations.El examen de la diversidad alélica del locus S en diez cultivares mallorquines de almendro ha mostrado la presencia del alelo Sf en cuatro de ellos, así como la presencia de cinco nuevos alelos no identificados hasta ahora. Aunque el alelo Sf se ha descrito como responsable de la expresión de la autocompatibilidad del almendro, recientemente se ha descubierto que tiene dos expresiones fenotípicas diferentes, por lo que no siempre se puede considerar un índice de la autocompatibilidad de los genotipos que lo presentan. El estudio de los cuatro cultivares mallorquines que presentan este alelo ha confirmado su autoincompatibilidad, de manera que este alelo se expresa en estos cultivares en su forma fenotípicamente activa, como también se ha comprobado en un grupo de cultivares del sur de Italia, lo que podría indicar una conexión entre estas dos poblaciones mediterráneas de almendro. [ca] L’examen de la diversitat al·lèlica del locus S en deu cultivars mallorquines d’ametller ha mostrat la presència de l’al·lel Sf en quatre, així com la presència de cinc al·lels nous fins ara no identificats. Encara que l’al·lel Sf s’ha descrit com a responsable de l’expressió de l’autocompatibilitat de l’ametller, fa poc que s’ha descobert que té dues expressions fenotípiques diferents, pel que no sempre es pot considerar un índex de l’autocompatibilitat dels genotips que el tenen. L’estudi de les quatre cultivars mallorquines que presenten aquest al·lel ha confirmat la seva autoincompatibilitat, de manera que aquest al·lel s’hi expressa en la seva forma fenotípicament activa, com també s’ha comprovat en un grup de cultivars del sud d’Itàlia, fet que podria indicar una connexió entre aquestes dues poblacions mediterrànies d’ametller

The definition of the European Almond Core collection

The European project 068 AGRI GEN RES 870/2004 has as an aim the definition of the European almond core collection. The methodology for creation of any core collection has to define how best to select entries using complex and incomplete accession data, as well as how and when to revise these decisions over time. The acquisition of data has been based on specific varietal descriptors, including morphological, physiological, phytopathological, genetic and chemical traits, following the descriptors defined by IBPGR/Bioversity, UPOV and the ECP/GR Prunus Working Group. Newly defined traits, not included in these descriptors, have also been considered because they are very important in defining the range of variability of the species. These traits include chilling and heat requirements for blooming, the molecular markers for genotype identification and the different chemical components of the kernel, as possible parameters for defining almond quality. As a result, a strategy to define the almond core collection was identified by highlighting the main steps to achieve in the near future.Peer ReviewedPrunus amygdalus Batschcore collectiongenetic resourcesgermplasmPublishe

Proyecto europeo para la valorización de recursos genéticos autóctonos de almendro y avellano. Trabajos realizados en España

Publishe

Pedigree analysis of 220 almond genotypes reveals two world mainstream breeding lines based on only three different cultivars

Loss of genetic variability is an increasing challenge in tree breeding programs due to the repeated use of a reduced number of founder genotypes. However, in almond, little is known about the genetic variability in current breeding stocks, although several cases of inbreeding depression have been reported. To gain insights into the genetic structure in modern breeding programs worldwide, marker-verified pedigree data of 220 almond cultivars and breeding selections were analyzed. Inbreeding coefficients, pairwise relatedness, and genetic contribution were calculated for these genotypes. The results reveal two mainstream breeding lines based on three cultivars: “Tuono”, “Cristomorto”, and “Nonpareil”. Descendants from “Tuono” or “Cristomorto” number 76 (sharing 34 descendants), while “Nonpareil” has 71 descendants. The mean inbreeding coefficient of the analyzed genotypes was 0.041, with 14 genotypes presenting a high inbreeding coefficient, over 0.250. Breeding programs from France, the USA, and Spain showed inbreeding coefficients of 0.075, 0.070, and 0.037, respectively. According to their genetic contribution, modern cultivars from Israel, France, the USA, Spain, and Australia trace back to a maximum of six main founding genotypes. Among the group of 65 genotypes carrying the Sf allele for self-compatibility, the mean relatedness coefficient was 0.125, with “Tuono” as the main founding genotype (24.7% of total genetic contribution). The results broaden our understanding about the tendencies followed in almond breeding over the last 50 years and will have a large impact into breeding decision-making process worldwide. Increasing current genetic variability is required in almond breeding programs to assure genetic gain and continuing breeding progress

Peculiaritats al·lèliques del locus <em>S</em> de les cultivars mallorquines d’ametller

The examination of the allelic diversity of the locus <em>S</em> in ten almond cultivars from Majorca has shown the presence of the <em>S_f</em> allele in four of them, as well as the presence of five new alleles non identified so far. Although the <em>S_f</em> allele has been described as responsible for the expression of self-compatibility in almond, it has been recently shown that this allele has two different phenotypic expressions. As a consequence, this allele cannot be always considered an index for self-compatibility of the genotypes harbouring it. The study of the four Majorcan cultivars possessing this allele has confirmed their selfincompatibility, showing that this allele is in its phenotypically active form, as it has been also observed in a group of cultivars from southern Italy, a fact possibly suggesting a connexion between these two Mediterranean almond populations.<br><br>El examen de la diversidad alélica del locus <em>S</em> en diez cultivares mallorquines de almendro ha mostrado la presencia del alelo <em>S_f</em> en cuatro de ellos, así como la presencia de cinco nuevos alelos no identificados hasta ahora. Aunque el alelo <em>S_f</em> se ha descrito como responsable de la expresión de la autocompatibilidad del almendro, recientemente se ha descubierto que tiene dos expresiones fenotípicas diferentes, por lo que no siempre se puede considerar un índice de la autocompatibilidad de los genotipos que lo presentan. El estudio de los cuatro cultivares mallorquines que presentan este alelo ha confirmado su autoincompatibilidad, de manera que este alelo se expresa en estos cultivares en su forma fenotípicamente activa, como también se ha comprobado en un grupo de cultivares del sur de Italia, lo que podría indicar una conexión entre estas dos poblaciones mediterráneas de almendro. [ca] L’examen de la diversitat al·lèlica del locus <em>S</em> en deu cultivars mallorquines d’ametller ha mostrat la presència de l’al·lel <em>S_f</em> en quatre, així com la presència de cinc al·lels nous fins ara no identificats. Encara que l’al·lel <em>S_f</em> s’ha descrit com a responsable de l’expressió de l’autocompatibilitat de l’ametller, fa poc que s’ha descobert que té dues expressions fenotípiques diferents, pel que no sempre es pot considerar un índex de l’autocompatibilitat dels genotips que el tenen. L’estudi de les quatre cultivars mallorquines que presenten aquest al·lel ha confirmat la seva autoincompatibilitat, de manera que aquest al·lel s’hi expressa en la seva forma fenotípicament activa, com també s’ha comprovat en un grup de cultivars del sud d’Itàlia, fet que podria indicar una connexió entre aquestes dues poblacions mediterrànies d’ametller