Utilização de fósforo e características do sistema radicular e da parte aérea da planta de arroz.

A seleção de plantas mais eficientes no uso do fósforo é importante para tornar mais econômica a cultura do arroz e, assim, maximizar a produção de grãos. Conduziu-se este trabalho com o objetivo de estudar as inter-relações que possam ocorrer entre a eficiência no uso do P e outras características da planta do arroz (Oryza sativa L.). Foram avaliados 25 genótipos de terras altas cultivados em solo e in vitro, nos níveis baixo (0 mg de P dm-3) e alto (150 mg de P dm-3, em solo, e 17 mg de P dm-3 em meio de cultura). Em solo com nível baixo de P, a altura e o número de raízes da planta foram as características que tiveram maior efeito direto na eficiência de utilização do P. No nível alto de P, o número de folhas e comprimento das raízes da planta foram as características que tiveram maior efeito direto. In vitro, tanto no baixo como no alto nível de P, o teor de P acumulado e o volume da raiz foram as características que tiveram maior efeito direto na eficiência de utilização do P

Avaliação de germoplasmas de arroz de sequeiro favorecido em Rio Branco, Acre.

Com o objetivo de conseguir material genético capaz de solucionar os principais problemas da cultura do arroz no Acre, vem sendo desenvolvido pela Embrapa/UEPAE de Rio Branco, um trabalho de avaliação de germoplasmas de arroz, sob a coordenação do Centro Nacional de Pesquisa de Arroz e Feijão.bitstream/item/117386/1/930.pd

Improving the performance of a radio-frequency localization system in adverse outdoor applications

In outdoor RF localization systems, particularly where line of sight can not be guaranteed or where multipath effects are severe, information about the terrain may improve the position estimate's performance. Given the difficulties in obtaining real data, a ray-tracing fingerprint is a viable option. Nevertheless, although presenting good simulation results, the performance of systems trained with simulated features only suffer degradation when employed to process real-life data. This work intends to improve the localization accuracy when using ray-tracing fingerprints and a few field data obtained from an adverse environment where a large number of measurements is not an option. We employ a machine learning (ML) algorithm to explore the multipath information. We selected algorithms random forest and gradient boosting; both considered efficient tools in the literature. In a strict simulation scenario (simulated data for training, validating, and testing), we obtained the same good results found in the literature (error around 2 m). In a real-world system (simulated data for training, real data for validating and testing), both ML algorithms resulted in a mean positioning error around 100 ,m. We have also obtained experimental results for noisy (artificially added Gaussian noise) and mismatched (with a null subset of) features. From the simulations carried out in this work, our study revealed that enhancing the ML model with a few real-world data improves localization’s overall performance. From the machine ML algorithms employed herein, we also observed that, under noisy conditions, the random forest algorithm achieved a slightly better result than the gradient boosting algorithm. However, they achieved similar results in a mismatch experiment. This work’s practical implication is that multipath information, once rejected in old localization techniques, now represents a significant source of information whenever we have prior knowledge to train the ML algorithm

Variação somaclonal em algumas características do grão e do ciclo da planta de arroz (Oryza sativa L.).

Estudou-se o efeito de dois meios de cultura na indução de variantes somaclonais em arroz com relação a algumas características do grão e do ciclo da planta para floração, usando -se a cultura de anteras. A frequência de surgimento de somaclones diferiu significativamente entre os dois meios estudados com relação às características de porcentagem de grãos inteiros no beneficiamento, classificação visual dos grãos e no ciclo das plantas na floração. Plantas originárias do meio sólido apresentaram, em média, maior porcentagem de grãos inteiros e menores índices de classificação visual e ciclo até a floração do que as plantas originárias do meio liquid

BRS Bonança: upland rice cultivar.

BRS Bonanca is an upland rice cultivar developed by Embrapa Rice and Beans and recommended for sowing in the states of Goias, Maranha, Mato Grosso, and Piaui. BRS Bonanca average grain yields were higher than the checks: flowered 80 days after germination; presented good cooking quality and resistance to the main rice diseases

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