The Amazon basin hosts the Earth's highest diversity of freshwater fish. Fish species have adapted to the basin's size and seasonal dynamics by displaying a broad range of migratory behaviour, but they are under increasing threats; however, no study to date has assessed threats and conservation of Amazonian migratory fishes. Here, the available knowledge on the diversity of migratory behaviour in Amazonian fishes is synthesized, including the geographical scales at which they occur, their drivers and timing, and life stage at which they are performed. Migratory fishes are integral components of Amazonian society. They contribute about 93% (range 77–99%) of the fisheries landings in the basin, amounting to ~US$436 million annually. These valuable fish populations are mainly threatened by growing trends of overexploitation, deforestation, climate change, and hydroelectric dam development. Most Amazonian migratory fish have key ecological roles as apex predators, ecological engineers, or seed‐dispersal species. Reducing their population sizes could induce cascading effects with implications for ecosystem stability and associated services. Conserving Amazonian migratory fishes requires a broad portfolio of research, management, and conservation actions, within an ecosystem‐based management framework at the basin scale. This would require trans‐frontier coordination and recognition of the crucial importance of freshwater ecosystems and their connectivity. Existing areas where fishing is allowed could be coupled with a chain of freshwater protected areas. Management of commercial and subsistence species also needs fisheries activities to be monitored in the Amazonian cities and in the floodplain communities to allow assessments of the status of target species, and the identification of management units or stocks. Ensuring that existing and future fisheries management rules are effective implies the voluntary participation of fishers, which can be achieved by increasing the effectiveness and coverage of adaptive community‐based management schemes.

Several studies conducted under high input conditions have indicated little susceptibility of pearl millet to water deficit untill early grain filling, because the losses in main shoot production were fully compensated by increased tiller fertility. The present study assessed the impact of water deficits at three development stages: prior to flowering (S30), at the beginning of flowering (S45), and at the end of flowering (S60) in pearl millet grown in experimental conditions similar to Sahelian farming conditions. It included a control irrigation treatment simulating the natural distribution of rainfall throughout the cropping season. Both biomass production and grain yield were severely reduced by S30 and S45, while S60 had no effect. In S30 and S45, the flowering of tillers was delayed or totally inhibited. In both of these treatments, the low number of productive tillers did not compensate for damage to panicle initiation and flowering of the main shoot. All treatments maintained green leaves on the main shoot during the grain filling period, and in S30 leaf growth recovered from mid-season drought. These results illustrate how pearl millet mostly escapes drought by matching its phenology to the mean rainfall distribution in the Sahel. In the case of mid-season drought, some late productive tillers and the maintenance of green leaf biomass of the main shoots limited, but did not overcome, the yield losses. This study stresses the importance of agro-ecological conditions in control treatments, particularly the water regime and crop density, when assessing crop drought resistance.

Summary• Experiments are presented that test the relative importance, during ontogeny, of stomatal control and leaf area expansion to optimum seasonal water use in pearl millet ( Pennisetum glaucum ). These parameters play a key role in the compromise between plant growth and water saving under unpredictable conditions of semiarid environments.• The response of growth and water use of crops to successive 15 d drought periods was measured under field conditions in Niger (West Africa).• From emergence to anthesis, biomass partitioning to stems and panicles depended strongly on leaf area development. Water use was linearly related to green leaf area duration in well watered plots, but was reduced proportionally more than green leaf area in drought-affected plots. The relations of crop growth rate and transpiration efficiency to leaf area depended on ontogenetic changes in biomass partitioning.• In P. glaucum , stomata play a dominant role in reducing crop water use under preanthesis drought, although this control becomes negligible after anthesis because of ontogenetic decline in the range of stomatal conductance. The rate of leaf senescence after anthesis is not drought-dependent.

This study is dedicated to the memory of Aurea Garcia Vasquez, dearest colleague and friend who succumbed to covid-19. We miss you.

IntroducciónLa diversidad de pisos ecológicos presentes en la Amazonía peruana, ha permitido a través de los siglos, la domesticación de numerosas especies de plantas nativas con una alta variabilidad genética (Zapata 2003). La impresionante diversidad biológica hace que muchas de estas especies no hayan sido estudiadas en profundidad, desconociendo aún muchas características biológicas, genéticas y fitoquímicas. Plukenetia volubilis L., sacha inchi es una planta nativa de la Amazonía peruana, cuyas semillas presentan altos contenidos de proteínas, ácidos grasos (esenciales: omegas 3, 6; omega 9) y vitamina E (tocoferoles y tocotrienoles) en cantidades significativamente mayores que otras semillas de oleaginosas como el maní, palma, soya, maíz, colza y girasol (Hamaker 1992).El valor del sacha inchi radica no sólo en los aspectos alimenticios, culturales e históricos, sino también en su rentabilidad económica. Siendo un cultivo con potencial rendimiento económico y grandes posibilidades de industrialización (Arévalo 1995), viene siendo intensamente cultivado; sin embargo, se observa una alta variabilidad genética, morfológica y fitoquímica, lo que ha generado que en el proceso de expansión del cultivo se hayan llegado a confundir especies del género Plukenetia. Hasta el año 2008 fueron descritas para la Amazonía peruana, cuatro especies en base a caracteres morfológicos: P. volubilis L., P. brachybotrya Müll. Arg., P. loretensis Ule, y P. polyadenia Müll. Arg. Recientemente fue descrita, para la región Amazonas, P. huayllabambana Bussmann, C. Téllez & A. Glenn. Nuestras observaciones en la morfología de algunas colecciones biológicas del Herbarium Amazonense (AMAZ) indican cierta sobreposición en algunos de los caracteres de estas especies, lo que podría dificultar su correcta determinación.Los marcadores moleculares constituyen poderosas herramientas para esclarecer cuestiones no resueltas mediante la taxonomía morfológica y para determinar los límites taxonómicos. Así, el ADN han sido utilizado para comprobar la sistemática morfológica o para cuestionarla (Judd et al. 1999). La litera- ResumenEn el presente trabajo se estudian cinco especies del género Plukenetia de la Amazonía peruana: P. brachybotrya, P. loretensis, P. polyadenia, P. huayllabambana, P. volubilis (procedencia San Martín); y de un supuesto morfotipo (P. volubilis, procedencia Cusco). Los 126 especímenes estudiados fueron identificados mediante claves de caracteres morfológicos (formas de hojas, tallos y semilla; posición de glándulas basilaminares) y posteriormente mediante marcadores moleculares ISSR (CAA, CAG, GACA). Los análisis morfológicos permitieron separar las cinco especies descritas: P. brachybotrya, P. loretensis, P. polyadenia, P. volubilis y P. huayllabambana. Los dos supuestos morfotipos de P. volubilis fueron discriminados por la posición de las glándulas, tamaño de semillas y forma del tallo. Los resultados proporcionados por el Análisis Factorial de Correspondencia (AFC) y corroborados por el Índice de fijación (F ST ), distan...

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To cite this version:Jean-François Renno, Thierry Winkel. Phenology and reproductive effort of cultivated and wild forms of Pennisetum glaucum under experimental conditions in the Sahel : implications for the maintenance of polymorphism in the species. Canadian Journal of Botany, National Research Council Canada, 1996, 74 (6)

The technique described here is a fast and simple method of extracting chloroplast DNA (cpDNA). It overcomes the need for differential centrifugation using density gradients. The leaves do not have to be kept in the dark and lyophilized before extraction, but lyophilization is still possible. The chloroplasts are specifically lysed in a cell extract of leaves, using a non-ionic detergent. After isolation by centrifugation, the cpDNA is purified by the combined action of proteolytic enzymes and detergents, followed by the elimination of proteins using a mixture of chloroform and isoamyl alcohol. This method provided good quality restriction profiles for all species analyzed.