Influência genotípica na absorção e na toxidez de manganês em soja

Abstract

RESUMO

Tolerance of <i>Urochloa brizantha</i> cv. MG5 to Mn Toxicity

“…The absence of toxicity signs may be due to sequestering of Mn in plant vacuoles and, thus, a decreased influence in plant metabolism [26]. The results confirm high resistance to toxicity in this forage plant since nutrient accumulation per plant (Figure 1(c)) did not affect production of dry matter (Figure 2(c)).…”

Changes in anatomy and root cell ultrastructure of soybean genotypes under manganese stress

“…The organization and order of the conducting veins, as well as the integrity of the cortical cells, play a fundamental role in nutrient absorption and transport processes. If on the one hand an organized arrangement of the conducting veins can allow a more efficient absorption (Rosolem et al, 2005) at low Mn availability, on the other hand, under excess Mn in the substrate, the maintenance of the cell integrity in the epidermis, exodermis, endodermis and cortex can confer greater root compartmentalization of Mn, reducing the long-distance transport and finally diminishing the toxicity in the shoot (Lavres Jr. et al, 2008). In this context, the apoplast "compartment", or free space, apparently acts as an effective tolerance mechanism to micronutrient excess, notably in tolerant (hyperaccumulator) plants, as recently discussed by Lavres Jr. et al (2008) and Führs et al (2008).…”

“…In IAC-Foscarin 31, under normal supply as well as excess Mn in the solution (Figures 2 IIIB and IIIC), inter-cellular spaces were observed, characterized as apoplast (or apparent free space). This possibly contributes to a greater accumulation and compartmentalization of Mn in the roots, which reduces the long-distance transport and confers greater tolerance to excess Mn (Lavres Jr. et al, 2008). This phenomenon is in agreement with reports of Führs et al (2008), who described that the leaf apoplast of cowpea (Vigna unguiculata L.), also a species of the Fabaceae family, is known for playing an important role in the tolerance to Mn excess/toxicity, due to the high peroxidase activity in this compartment.…”

Interação cálcio e boro na fixação biológica de nitrogênio na soja: avaliação morfológica, ultraestrutural e da atividade da nitrogenase

“…Para quantificação do comprimento e da superfície radicular de cada unidade experimental, a raiz de cada planta foi coletada inteira, cortou-se então vertical e horizontalmente o volume de raízes, evitando-se a raiz pivotante (LAVRES JUNIOR et al, 2008). Em seguida, essa subamostra foi colocada em copo plástico contendo água desionizada, e então armazenada na temperatura de ± 10 ºC, em geladeira (NOORDWIJK; FLORIS, 1979), a fim de se evitar a desidratação e a perda de matéria seca durante a manipulação (separação das raízes na cubeta do scanner), devido à respiração.…”

“…Os valores totais de comprimento e de superfície (área superficial cilíndrica) foram prontamente calculados pelo software, relacionando-se os valores da amostra e de sua matéria seca com a matéria seca total de raízes de cada unidade experimental (LAVRES JUNIOR et al, 2008). JUNIOR et al, 2009;2012).…”