Abstract
Though stone pine is currently a genuine forest tree of Mediterranean ecosystems, its use as grafted orchards crop for its edible pine nuts is potentially feasible. Therefore, genetic improvement of the species has been undertaken by several Spanish forest administrations, establishing in the Nineties experimental clonal orchards by grafting scions from plus trees, selected for their outstanding cone yield in pine forests of the main Spanish provenance regions. This paper analyses the coming into production of four clonal trials located at the National Forest Breeding Centre «Puerta de Hierro», Madrid. The four different-aged orchards showed a strong, synchronized masting habit. Estimations are given for the degree of genetic determination of cone production and for clonal improvement values. Due to the presence of strong size-yield correlations and spatial autocorrelations, genetic parameters were estimated by an individual tree cone-yield model adjusted for environmental tree size differences and for correlations between nearest neighbours (NN). The degree of genetic determination H2, estimated in less than 20% without adjustments, reached 30-38% adjusting for environmental size variation and 45-73% after spatial adjustment, with parallel increments in clonal improvement values and expected genetic gain. The results allow rogueing the four clone banks, progressing in the domestication of the stone pine as nut crop.
Highlights
Para ello, la primera tarea fue la prospección masal de árboles grandes productores de piña en las principales regiones de procedencia de la especie, abordada a finales de los años ochenta y principios de los noventa del siglo pasado
Estimations are given for the degree of genetic determination of cone production and for clonal improvement values
Due to the presence of strong size-yield correlations and spatial autocorrelations, genetic parameters were estimated by an individual tree cone-yield model adjusted for environmental tree size differences and for correlations between nearest neighbours (NN)
Summary
El resultado de esta sequía fue una considerable reducción del peso medio de piña en 2005, casi la mitad comparado con el año anterior lluvioso y muy por debajo de años normales: de hecho, exceptuando las primeras cosechas post-plantación de cada banco, el peso medio de piña en cada cosecha invernal guardó una relación lineal directa con la precipitación del año forestal anterior (r 0,98 para el peso medio de piña de los tres primeros bancos entre 2001-2005; Fig. 3). Según los conteos en el Banco 4 (Fig. 2) y una estimación visual en los otros tres bancos, la muestra en árbol para la cosecha 2006/07 se asemeja en número de piña a la cosecha anterior, pero recuperando un tamaño medio de piña normal, con una muestra algo menor para 2007/08
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