Recycled alkaline paper waste influenced growth and structure of Pinus taeda L. forest

Alkaline residues of recycled paper production (ARRP) can be an alternative for correcting soil acidity and adding bases to Pinus taeda L. systems. Our aim was to investigate the effect of increasing doses of ARRP on tree, forest floor (litter and root), and soil composition in a 3-year-old Brazilian pine forest plantation. In 2007, ARRP treatments of 0, 10, 20, 30 and 40 T ha^?1 were imposed. Tree growth and needle elemental composition were evaluated in 2008 and 2018; elemental composition of the trunk was evaluated in 2018. In 2017, accumulation and composition of litter layers were assessed: new litter, old litter, first and second sublayers of fragmented litter (Fr and Fm), and the humified layer (H); roots present in F and H layers were quantified (amount and elemental composition). In addition, soil chemical properties at different depths were evaluated in 2008, 2012, and 2017. The application of ARRP improved growth by ~?16% up to 20 T ha^?1 after 10 years. Also, ARRP increased Ca concentration in needles, trunks, roots, and all litter fractions since Ca was a major component of ARRP. There was no change in total litter accumulation with ARRP application, but an increase in the humidified fraction was observed. Root growth was enhanced by ARRP, leading to great changes in root composition in Fr and H fractions. Changes in soil pH, Ca²⁺, and Al³⁺ were observed in the 0–10 cm soil layer. Findings suggest that application of ARRP to established pine forests has the potential for improving productivity.

     

Laboratory evaluation of the effects of Manilkara subsericea (Mart.) Dubard extracts and triterpenes on the development of Dysdercus peruvianus and Oncopeltus fasciatus

BACKGROUND: Studies were carried out to evaluate the effects of Manilkara subsericea extracts and triterpenes on the development of two species of agricultural pest insects, Oncopelus fasciatus and Dysdercus peruvianus. RESULTS: All treatments of insects with M. subsericea extracts induced mortality, delayed development and inhibited moulting. Some extracts assayed (FH, FB and FD in D. peruvianus, and FH, FB and FEA in O. fasciatus) also produced body deformities in the few adults that emerged. Other extracts (FH, FEA, FB, FD and LET in both insects), however, induced either permanent (overaged) or extranumerary nymphs, both of which were unable to achieve the adult stage and reproductive status. The insects were also treated with triterpenes (α‐ and β‐amyrin acetates) which showed high lethality at 30 days after treatment and delayed the intermoult period so that overaged nymphs were detected. CONCLUSION: The results indicate that extracts and triterpenes from Manilkara subsericea act as potent growth inhibitors of phytophagous hemipteran nymphs. It is also concluded that the mixture of several different molecules in the extracts used produces synergic effects that do not occur after using the triterpenes (PFT) alone. These secondary metabolites in the M. subsericea extracts can potentially be used in integrated control programmes against crop pests. Copyright © 2012 Society of Chemical Industry