Reginaldo de Carvalho

Oxalis L. (Oxalidaceae) no Estado de Pernambuco, Brasil

This study was based on morphological analyses from both herbaria and field material. Nine species were recorded, distinguished from each other mainly by the root system, phyllotaxis, leaf type, color of the flowers and inflorescence and capsule morphology. Of these species, two (Oxalis corniculata L. and O. cratensis Oliver ex Hooker) showed preferential distribution from the Litoral and Forest zones to the Agreste subzone. Oxalis psoraleoides Kunth is widely distributed over the entire state. Oxalis triangularis A. St.-Hil. and O. frutescens L. are distributed from the Littoral and Forest zones to the Sertao subzone. Oxalis divaricata Mart. ex Zucc. is distributed in the Agreste and Forest subzones, occurring also at Fernando de Noronha Archipelago. Oxalis hedysarifolia Raddi occurs in the Forest zone and in the Agreste subzone, where it is restrict to the mountains. Oxalis debilis Kunth is restricted to the Agreste zone, and Oxalis glaucescens Norlind is the only one found exclusively in sandy caatingas, in the Sertao subzone. Identification keys, comments on the affinities and geographic distribution, as well as illustrations, are presented.

Bioactivity of basil ( Ocimum basicilum L.) on control of the spider mite ( Tetranychus urticae Koch.) in peanut

Essential plant oils contain biopesticides that could be used to control many crop pests. Tetranychus spp. are mites that cause damage to several crops and are primarily controlled by synthetic pesticides. Literature showed that mites can be controlled with essential oils of plants containing eugenol. In this work, we evaluated the bioactivity of basil (Ocimum basicilum) accessions for peanut-spider mites control based on molecular, biochemical and agronomic assays. RNA from four basil accessions, previously chosen by divergence genetic analysis, were used to estimate the expression of eugenol synthase (EGS I) transcripts, by semiquantitative and polymerase chain reaction (qPCR) assays. Chromatography was, thereafter, performed in order to estimate the eugenol concentration. Feeding bioassays were performed using basil leaf extracts in order to estimate oviposition and mortality of spider mites females. Finally, a validation assay was carried out in greenhouse, using peanut plants previously infested with spider mites and weekly sprayed with basil water-extract. One basil accession, OVRS, revealed high phytotoxicity to spider mite females, at 15% water-extract. The mortality rate was 75% and complete inhibition of fecundity was found in BOD assays. In the greenhouse assay, the most severe damage due to mite infestations was found to plant height, number of pods and pod yield, which were reduced to 28, 53 and 52% in non-treated plants (control). Considering that basil is a short-cycle plant, with easy reproduction and management, these results represent an accessible alternative to organic control spider mites in peanut.