Epistatic effects on grain yield of soybean [Glycine max (L.) Merrill]

Studies addressing the estimation of genetic parameters in soybean have not emphasized the epistatic effects. The purpose of this study was to estimate the significance of these effects on soybean grain yield, based on the Modified Triple Test Cross design. Thirty-two inbred lines derived from a cross between two contrasting lines were used, which were crossed with two testers (L1 and L2). The experiments were carried out at two locations, in 10 x 10 triple lattice designs with 9 replications, containing 32 lines (Pi ), 64 crosses (32 Pi x L1 and 32 Pi x L2 ) and controls. The variation between ( ͞L1i + ͞L2i - ͞Pi ) revealed the presence of epistasis, as well as an interaction of epistasis x environment. Since the predominant component of epistasis in autogamous species is additive x additive (i type), we suggest postponing the selection for grain yield to later generations of inbreeding in order to exploit the beneficial effects of additive x additive epistasis.

Purification of bromelain from pineapple wastes by ethanol precipitation

Bromelain is an aqueous extract of pineapple that contains a complex mixture of proteases and non-protease components. These enzymes perform an important role in proteolytic modulation of the cellular matrix in numerous physiologic processes, including anti-inflammatory, anti-thrombotic and fibrinolytic functions. Due to the scale of global production of pineapple (Ananas comosus L.), and the high percentage of waste generated in their cultivation and processing, several studies have been conducted on the recovery of bromelain. The aim of this study was to purify bromelain from pineapple wastes using an easy-to-scale-up process of precipitation by ethanol. The results showed that bromelain was recovered by using ethanol at concentrations of 30% and 70%, in which a purification factor of 2.28 fold was achieved, and yielded more than 98% of the total enzymatic activity. This enzyme proved to be susceptible to denaturation after the lyophilization process. However, by using 10% (w/v) glucose as a cryoprotector, it was possible to preserve 90% of the original enzymatic activity. The efficiency of the purification process was confirmed by SDS-PAGE, and native-PAGE electrophoresis, fluorimetry, circular dichroism and FTIR analyzes, showing that this method could be used to obtain highly purified and structurally stable bromelain. (C) 2012 Elsevier B.V. All rights reserved.

Genetic variation of the Ananas genus with ornamental potential

Brazil is one of the main centers of origin of pineapple species presenting the largest genetic variation of the Ananas genus. Embrapa Cassava and Fruits is a Brazilian Agricultural Research Corporation and has an ex-situ collection of 678 accessions of the Ananas genus and some other Bromeliaceae. The use of ornamental pineapple has increased in the last years demanding new varieties, mainly for the external market, due to the originality and colors of its tiny fruits. The main aim of the present study was describing accessions from the pineapple gene bank in order to quantify their genetic variation and identify possible progenitors to be used in breeding programs of ornamental pineapples. Eighty-nine accessions of Ananas comosus var. comosus, A. comosus var. bracteatus (Lindl.) Coppens et Leal, A. comosus var. ananassoides (Baker) Coppens et Leal, A. comosus var. erectifolius (L. B. Smith) Coppens et Leal, A. comosus var. parguasensis (Camargo et L. B. Smith) Coppens et Leal and A. macrodontes Morren were evaluated with 25 morphological descriptors. According to the results, the evaluated accessions were separated into the following categories: landscape plants, cut flower, potted plants, minifruits, foliage and hedge. The genetic distance among accessions was determined using the combined qualitative and quantitative data by the Gower algorithm. The pre-selected accessions presented genetic variation and ornamental potential for different uses. The multicategory analysis formed seven clusters through a classification method based on the average Euclidean distance between all accessions using the cut-point of genetic dissimilarity (D dg = 0.35). The genotypes A. comosus var. erectifolius were selected to be used as landscape plants, cut flower, minifruits and potted plants. Accessions of A. comosus var. bracteatus and A. macrodontes were selected as landscape plants and hedge. The highest variation was observed in A. comosus var. ananassoides genotypes, which presented high potential for use as cut flowers.

Nitric Oxide Mediates the Hormonal Control of Crassulacean Acid Metabolism Expression in Young Pineapple Plants

Genotypic, developmental, and environmental factors converge to determine the degree of Crassulacean acid metabolism (CAM) expression. To characterize the signaling events controlling CAM expression in young pineapple (Ananas comosus) plants, this photosynthetic pathway was modulated through manipulations in water availability. Rapid, intense, and completely reversible up-regulation in CAM expression was triggered by water deficit, as indicated by the rise in nocturnal malate accumulation and in the expression and activity of important CAM enzymes. During both up-and down-regulation of CAM, the degree of CAM expression was positively and negatively correlated with the endogenous levels of abscisic acid (ABA) and cytokinins, respectively. When exogenously applied, ABA stimulated and cytokinins repressed the expression of CAM. However, inhibition of water deficit-induced ABA accumulation did not block the up-regulation of CAM, suggesting that a parallel, non-ABA-dependent signaling route was also operating. Moreover, strong evidence revealed that nitric oxide (NO) may fulfill an important role during CAM signaling. Up-regulation of CAM was clearly observed in NO-treated plants, and a conspicuous temporal and spatial correlation was also evident between NO production and CAM expression. Removal of NO from the tissues either by adding NO scavenger or by inhibiting NO production significantly impaired ABA-induced up-regulation of CAM, indicating that NO likely acts as a key downstream component in the ABA-dependent signaling pathway. Finally, tungstate or glutamine inhibition of the NO-generating enzyme nitrate reductase completely blocked NO production during ABA-induced up-regulation of CAM, characterizing this enzyme as responsible for NO synthesis during CAM signaling in pineapple plants.

Thermoperiod affects the diurnal cycle of nitrate reductase expression and activity in pineapple plants by modulating the endogenous levels of cytokinins

Nitrate reductase (NR, EC 1.6.6.1) activity in higher plants is regulated by a variety of environmental factors and oscillates with a characteristic diurnal rhythm. In this study, we have demonstrated that the diurnal cycle of NR expression and activity in pineapple (Ananas comosus, cv. Smooth Cayenne) can be strongly modified by changes in the day/night temperature regime. Plants grown under constant temperature (28 degrees C light/dark) showed a marked increase in the shoot NR activity (NRA) during the first half of the light period, whereas under thermoperiodic conditions (28 degrees C light/15 degrees C dark) significant elevations in the NRA were detected only in the root tissues at night. Under both conditions, increases in NR transcript levels occurred synchronically about 4 h prior to the corresponding elevation of the NRA. Diurnal analysis of endogenous cytokinins indicated that transitory increases in the levels of zeatin, zeatin riboside and isopentenyladenine riboside coincided with the accumulation of NR transcripts and preceded the rise of NRA in the shoot during the day and in the root at night, suggesting these hormones as mediators of the temperature-induced modifications of the NR cycle. Moreover, these cytokinins also induced NRA in pineapple when applied exogenously. Altogether, these results provide evidence that thermoperiodism can modify the diurnal cycle of NR expression and activity in pineapple both temporally and spatially, possibly by modulating the day/night changes in the cytokinin levels. A potential relationship between the day/night NR cycle and the photosynthetic pathway performed by the pineapple plants (C(3) or CAM) is also discussed.

Maize and soybeans production in integrated system under no-tillage with different pasture combinations and animal categories

The adoption of no-till system (NTS) combined with crop-livestock integration (CLI) has been a strategy promoted in Brazil, aiming to maximize areas yield and increase agribusiness profitability. This study aimed to evaluate grains yield and phytotechnical attributes from maize and soybean culture by CLI system under NTS after winter annual pure and diversified pastures with the absence or presence of grazing animals. The experiment was installed in Castro (Parana State, Brazil) on in a dystrophic Humic Rhodic Hapludox with a clay texture, using experimental design of randomized complete blocks in 4 x 2 factorial scheme with three replications. Treatments included four pasture combinations (diversified or pure) and animal categories (light and heavy) subjected or not to grazing animals during the winter. During 2008/09 and 2009/10 summers, the area was cultivated with soybeans and maize, respectively, with yield assessment of grains and phytotechnical attributes. Treatments did not alter the yield and weight of a thousand seeds (WTS) of soybeans. In maize culture, the grazing animal during the winter increased the plant population and grains yield, but gave slight decrease in WTS. Pasture combinations (diversified or pure) and animal categories (light and heavy) did not interfere in soybean culture, but benefited the maize crop.

Institutional arrangements in the emerging biodiesel industry: Case studies from Minas Gerais-Brazil

Connecting (small) family farmers to the emerging biodiesel industry requires careful design of the institutional arrangements between the producers of oil crops and the processing companies. According to institutional economics theory, the design of effective and efficient arrangements depends on production and transaction characteristics, the institutional environment, and the organizational environment supporting the transaction between producers and the industry. This paper presents a comparative study on two cases in the feedstock-for-biodiesel industry in the state of Minas Gerais, Brazil. The two case studies represent the production and transaction system of soybeans (Glycine max L Merrill) and castor beans (Ricinus communis L). Important elements of effective and efficient institutional arrangements are farmer collective action, availability of technical and financial support, and farmer experience with particular crops. (C) 2011 Elsevier Ltd. All rights reserved.

Adubação mineral com cobalto e molibdênio na cultura da soja

Altas produtividades de soja requerem grandes quantidades de nitrogênio, que podem ser obtidas principalmente, a partir da fixação simbiótica. No entanto, há possibilidade da eficiência desse processo biológico ser prejudicada pela deficiência de micronutrientes, especialmente de cobalto e molibdênio. Nesse contexto, objetivou-se com o presente trabalho avaliar a eficiência agronômica e a forma de aplicação de adubação mineral com cobalto e molibdênio na cultura da soja. Para tanto, a cultivar CD-206 foi submetida a diferentes tratamentos que consistiram da combinação entre aplicação de Co e Mo via tratamento de sementes e adubação foliar. As características agronômicas avaliadas foram o número de nódulos, massa seca da parte aérea, massa seca de raiz, número de vagens, número de grãos, massa de mil grãos e produção de grãos. A aplicação de molibdênio e cobalto via sementes e/ ou adubação foliar no estádio V4 (terceira folha trifoliolada completamente desenvolvida, quarto nó) promoveram incrementos significativos no rendimento da cultura. Respostas positivas ao cobalto e molibdênio também foram observadas no número de nódulos, vagens e grãos, com aumentos de até 240 kg ha-1 no rendimento da cultura. Os parâmetros agronômicos avaliados foram afetados positivamente pela aplicação de Co e Mo, principalmente quanto aplicado tanto via semente como foliar (TS + V4), inclusive para a produtividade de grãos. A forma de aplicação não foi significativamente distinta, ou seja, tanto a aplicação via semente como via foliar foram eficientes no fornecimento destes nutrientes para a cultura da soja.

Análise de imagens na avaliação de danos mecânicos em sementes de soja

A injúria mecânica é um dos mais importantes fatores na redução da qualidade de sementes de soja. Neste contexto, este trabalho objetivou avaliar a influência da pressão de impacto e o teor de água em sementes, bem como a aplicabilidade da técnica de análise de imagens, na ocorrência de danos mecânicos em sementes de soja. Sementes das cultivares Vencedora e Monsoy 8001, com teores de água de 13% e 18%, foram submetidas a danos mecânicos, com a utilização de equipamento simulador de impactos (551,6 KPa e 965,3 KPa). Posteriormente, as sementes foram secas a 32ºC, até atingirem 12% de teor de água. Imediatamente após os impactos e após cinco meses de armazenamento, as sementes foram avaliadas pelos testes de tetrazólio e raios X. A pressão de impacto e o teor de água nas sementes exerceram efeitos diretos na severidade do dano mecânico, porém, o local do impacto exerceu maior influência do que aqueles fatores. A técnica de análise de imagens foi de grande utilidade na avaliação de danos mecânicos em sementes de soja, possibilitando a análise detalhada dos efeitos de diferentes fatores.