Drought modulates interactions between arbuscular mycorrhizal fungal diversity and barley genotype diversity

Droughts associated with climate change alter ecosystem functions, especially in systems characterized by low biodiversity, such as agricultural fields. Management strategies aimed at buffering climate change effects include the enhancement of intraspecific crop diversity as well as the diversity of beneficial interactions with soil biota, such as arbuscular mycorrhizal fungi (AMF). However, little is known about reciprocal relations of crop and AMF diversity under drought conditions. To explore the interactive effects of plant genotype richness and AMF richness on plant yield under ambient and drought conditions, we established fully crossed diversity gradients in experimental microcosms. We expected highest crop yield and drought tolerance at both high barley and AMF diversity. While barley richness and AMF richness altered the performance of both barley and AMF, they did not mitigate detrimental drought effects on the plant and AMF. Root biomass increased with mycorrhiza colonization rate at high AMF richness and low barley richness. AMF performance increased under higher richness of both barley and AMF. Our findings indicate that antagonistic interactions between barley and AMF may occur under drought conditions, particularly so at higher AMF richness. These results suggest that unexpected alterations of plant-soil biotic interactions could occur under climate change

Use of sawdust Eucalyptus sp. in the preparation of activated carbons Utilização de serragem de Eucalyptus sp. na preparação de carvões ativados

Wood sawdust is a solid residue, generated in the timber industry, which is of no profitable use and can cause serious environmental problems if disposed inadequately. The aim of this study was to use the eucalyptus sawdust in the preparation of activated carbons AC) and test them as adsorbents of methylene blue (MB) and phenol, representative pollutants from aqueous effluents of various industries. The eucalyptus sawdust was characterized by instrumental analysis such as elementary analysis (CHNS-O), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The activated carbons were prepared by physical activation with carbon dioxide AC_CO2, (10º C min-1, 850º C, 1h) and by chemical activation with potassium carbonate AC_K2CO3 (10º C min-1, 850º C, 3h). The AC_CO2 and AC_K2CO3 were characterized by CHN-O, TGA, FTIR, N2 adsorption/desorption (BET) to evaluate the specific surface area and SEM. The resulting activated carbons were tested for their ability to adsorb MB and phenol in water. The activated carbons produced in this work were predominantly microporous and showed specific surface area of about 535 m² g-1. The AC_K2CO3 was more effective in the adsorption of MB (81 mg g-1) and phenol (330 mg g-1) than AC_CO2 (32 mg g-1 and 172 mg g-1, respectively, for MB and phenol).<br>A serragem é um resíduo sólido, gerado na indústria madeireira, que não tem uso rentável e pode causar sérios problemas ambientais quando disposta inadequadamente. Neste estudo, objetivou-se utilizar a serragem de eucalipto na preparação de carvões ativados (AC) e testá-los como adsorventes do corante azul de metileno (MB) e fenol; moléculas que representam poluentes de efluentes industriais. A serragem de eucalipto foi caracterizada por análises instrumentais, tais como: análise elementar (CHNS-O), análise termogravimétrica (TGA), espectroscopia na região do infravermelho (FTIR) e microscopia eletrônica de varredura (SEM). Os carvões ativados foram preparados por ativação física com dióxido de carbono AC_CO2, (10º Cmin-1, 850ºC, 1h) e pela ativação química com carbonato de potássio- AC_K2CO3 (10º Cmin-1, 850º C, 3h). O AC_CO2 e AC_K2CO3 foram caracterizados por CHN-O, TGA, FTIR, adsorção/dessorção de N2 (área BET) para avaliar a área superficial específica e SEM. Os carvões ativados resultantes foram testados quanto à capacidade de adsorver MB e fenol na água. Os carvões produzidos apresentaram características de material microporoso, apresentando área superficial média de cerca de 535 m²g-1. O AC_K2CO3 foi mais eficiente na adsorção do MB (81mgg-1) e fenol (330mgg-1) que o AC_CO2 (32mg g-1 e 172 mg g-1, respectivamente, para MB e fenol)