Does selective logging affect the leaf structure of a late successional species?

The anatomical characteristics of both sun and shade leaves of Alseis pickelii were investigated in order to evaluate the consequences of selective logging (in seasonally dry Atlantic Forest) on the leaf structure of this species. Fully expanded sun and shade leaves were collected in two distinct stands of tabuleiro forest; a stand of recently logged forest and an unlogged stand. Only leaves from the unlogged stand revealed significantly different magnitudes of response to light regimes, producing leaves with structural characteristics associated with different levels of irradiance. The sun leaves from this stand had a thicker adaxial surface, mesophyll, palisade and spongy parenchyma, a secondary cell wall of fibers and a lower leaf area compared with the shade leaves. However, in the logged stand, the leaf cuticles of sun and shade leaves showed no significant differences, although the leaf area of the sun leaves was higher than the shade leaves. According to these data, we concluded that the unlogged stand produced typical "sun" and "shade" leaves. In contrast, leaves from the logged stand showed a lower variation of types, where neither typical "sun" nor typical "shade" leaves were produced, suggesting lower leaf plasticity of this late successional tree in this area

Evaluation of soapberry (Sapindus saponaria L.) leaf extract against papaya anthracnose

<div><p>ABSTRACT Chemical fungicides provide the primary means to control fungal infection in fruits and vegetables in the postharvest. Exploitation of natural products to control decay and prolong the storage life of perishables has received more attention. In this study, hydroethanolic extracts from the leaves of soapberry (Sapindus saponaria L.) were investigated for their inhibitory activity against the fungus Colletotrichum gloeosporioides, the causal agent of anthracnose in papaya fruits. To evaluate the antifungal activity of the plant extract, the latter was incorporated into potato-dextrose-agar (PDA) medium at different concentrations (10, 50 and 100 mg mL-1), and mycelial growth inhibition, spore production inhibition and morphological changes were evaluated at room temperature after 7 days. Efficacy of the extract was noted when it was used at 50 mg mL-1 and 100 mg mL-1, resulting in a reduction in the mycelial growth (P< 0.05). At 50 mg mL-1, the extract causes morphological changes by reducing the size of hyphae, which become shorter and more branched. At 100 mg mL-1 extract, damages in the hyphal structure were more severe, causing mycelial rupture. In vivo treatment with 100 mg mL-1 extract prevented the development of anthracnose symptoms in fresh papaya fruits. Soapberry leaf extract has strong inhibitory activity against C. gloeosporioides, preventing the mycelial growth and reducing the appearance of anthracnose symptoms. Taken together, these results demonstrated the potential of this extract as a natural fungicide, constituting an alternative measure for disease control in papaya fruits.</p></div