Magnesium, calcium and potassium in seeds and cotyledons of common bean and its translocation to the young plants

O presente estudo objetivou avaliar os teores de magnésio, cálcio e potássio em sementes e cotilédones do feijoeiro (Phaseolus vulgaris L. cv. Carioca) e a transferência desses minerais dos cotilédones para a planta. Para tanto, plantas de feijão foram cultivadas durante a fase de existência dos cotilédones e irrigadas com água desmineralizada. Foram realizadas três colheitas dos cotilédones das plantas jovens, escolhidas ao acaso de dez repetições, antes da ocorrência de senescência e queda, aos 8, 12 e 15 dias após a germinação das sementes. Em cada colheita, determinaram-se as matérias fresca e seca dos cotilédones e teores de magnésio, cálcio e potássio. Esses parâmetros também foram avaliados em sementes retiradas do mesmo lote. Os resultados demonstraram que o potássio existe nas sementes e cotilédones em maior teor, seguido, em ordem decrescente, pelo magnésio e cálcio. Na 1a colheita dos cotilédones, realizada oito dias após a germinação, 59% de magnésio, 78% de cálcio e 71% de potássio já tinham sido transferidos para as plantas. Na última colheita, realizada 15 dias após germinação, essas porcentagens eram de 73%, 82% e 91%, respectivamente. Desta forma, o mineral menos transferido foi o magnésio, e o mais translocado, o potássio.Magnesium, calcium and potassium concentration in the seeds and cotyledons of Phaseolus vulgaris L. cv. Carioca and its translocation from the cotyledons to the plant were evaluated. For such an evaluation plants were cultivated during the cotyledons phase and were irrigated with deionized water. Three samplings of cotyledons completely randomized were done and replicated ten times, before its senescence and fall, at 8, 12 and 15 days after the germination of the seeds. Fresh and dry matter of the cotyledons and its magnesium, calcium and potassium content were determinated in every sample. These parameters were also determined in the seeds from the same lot. Potassium concentration was higher than magnesium in both seeds and cotyledons. Calcium presented the lesser concentration both in seeds and cotyledons. These minerals were translocated from the seeds and cotyledons to the young plants. Eight days after germination 59% of the magnesium, 78% of the calcium and 71% of the potassium were translocated to the plants. Fifteen days after germination these percentages were respectivaley 73%, 82% and 91%. Thus, magnesium was the less and potassium was the most translocated mineral at the end of the study

INTERAÇÕES ENTRE MAGNÉSIO E MICRONUTRIENTES METÁLICOS DURANTE O DESENVOLVIMENTO DE FEIJOEIRO, em SOLUÇÃO NUTRITIVA

Este estudo avaliou as possíveis interações entre o magnésio e os micronutrientes manganês, zinco, cobre e ferro, pela determinação de seus teores nos diferentes órgãos do Phaseolus vulgaris L. cv Carioca, nas 5 coletas, realizadas a cada 14 dias, a partir do 25o dia após a semeadura. As plantas foram cultivadas em solução nutritiva com nível completo (48,6 mg.L-1), baixos (2,4 e 24,3 mg.L-1) e elevados (72,9 e 97,2 mg.L-1) de Mg. O delineamento experimental foi inteiramente casualizado, em esquema fatorial. Com os níveis baixos de Mg, observou-se a diminuição do teor desse mineral nas raízes, caule e folhas e de Cu nas folhas e o aumento de Zn nas folhas e de Mn nas raízes. Com 97,2 mg.L-1 de Mg, observou-se o aumento desse elemento nas folhas, sugerindo sua absorção e translocação das raízes para a parte aérea. Nesses feijoeiros também observou-se diminuição de Cu no caule e nos frutos e de Mn nas raízes. As concentrações de Mg e Mn nas raízes variaram sempre de modo oposto, com os diferentes tratamentos utilizados. Isso sugere uma relação inversa na absorção desses nutrientes. Os resultados demonstraram uma pequena influência da variação dos níveis de Mg na solução sobre os micronutrientes que, no entanto, pode alterar o comportamento da planta.This study was carried out to evaluate interactions between magnesium and the micronutrients manganese, zinc, copper and iron, determining their concentrations in different parts of Phaseolus vulgaris L. cv Carioca. Bean plants were grown in pots containing nutrient solutions with low ms levels (2.4 and 24.3 mg.L-1), standard (48.6 mg.L-1) and high levels (72.9 and 97.2 mg.L-1). The experimental design was a completely randomized factorial, with 5 magnesium levels and 5 samplings every 14 days, starting 25 days after sowing. Plants grown at Mg levels below 48.6 mg.L-1 had lower Mg concentration in roots, stem and leaves; lower Cu concentration in leaves; higher Zn concentration in leaves, and higher Mn concentrations in roots in comparison to the control. When magnesium level was 97.2 mg.L-1 plants had higher Mg concentration in leaves, suggesting its absorption and translocation from root to shoot. These plants also revealed lower Cu concentration in stem and fruits and lower Mn concentration in the roots. Mg and Mn concentration in roots varied always in opposite direction, suggesting an inverse relationship in the absorption of these elements. Changes in Mg levels in nutrient solution caused little effects in the concentration of micronutrients but can cause significant differences in the development of the common bean

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora