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Merah O.,ENSIACET | Merah O.,French National Institute for Agricultural Research | Monneveux P.,International Potato Center Centro Internacional Of La Papa Cip
Journal of Agronomy and Crop Science | Year: 2015

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post-anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source-sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source-sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non-destructive estimation of the variation in the contribution of different organs to grain filling. © 2015 Blackwell Verlag GmbH. Source

De Haan S.,International Potato Center Centro Internacional Of La Papa Cip | Nnez J.,International Potato Center Centro Internacional Of La Papa Cip | Bonierbale M.,International Potato Center Centro Internacional Of La Papa Cip | Ghislain M.,International Potato Center Centro Internacional Of La Papa Cip
Mountain Research and Development | Year: 2010

Botanical species and morphological and genetic diversity represent different yet linked units of conservation. These features, and their spatial distribution in the central Peruvian Andean highlands of Huancavelica, were used as a basis for characterizing and quantifying potato agrobiodiversity at different scales. Results show that individual farm households maintain high levels of cultivar, morphological, and genetic diversity. At the regional level, all cultivated species, with the exception of Solanum ajanhuiri, were found to be present. Tetraploid native potatoes were most abundant, followed by diploids, triploids, and pentaploids. Morphological characterization of 2481 samples belonging to 38 in situ collections resulted in the identification of 557 unique cultivars. Genetic fingerprinting of 989 samples belonging to 8 in situ collections resulted in the identification of 406 unique cultivars. The principal source of genetic variation is found within rather than between geographically distanced subpopulations. High levels of cultivar diversity are found, particularly at elevations between 3850 and 4150 m. © 2010 International Mountain Society. Source

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