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Piracicaba, Brazil

de Camargo M.S.,Polo Centro Sul | Korndorfer G.H.,Federal University of Uberlandia | Foltran D.E.,APTA Polo Centro Sul
Bioscience Journal | Year: 2014

Although silicon and sugarcane have been studied for decades in Brazil, there is little information regarding Si absorption by cultivars over time the relationship borer stalk incidence under field conditions. The objective of this study was to evaluate silicon uptake by above-ground dry mass and stalk borer incidence in nine sugarcane cultivars in two ratoon crops of sugarcane. The experiments were conducted in two ratoons in randomized complete blocks design with four replications and nine varieties (IAC 86-2480, IAC 91-1099, IAC 87-3396, IACSP 94-4004, IACSP 93-6006, IACSP-93-3046, IACSP-94-2094, IACSP 94-2101, RB 86-7515) in soil with high soluble Si (Kandiustalf). Silicon concentration on leaves +1 (TVD, top visible dewlap), sugarcane yield, Si uptake by by above-ground dry mass and stalk borer incidence. The IAC91-1099 showed highest cane yield (123.6 e 106.1 t ha-1), silicon uptake by above-ground dry mass (165.6 e 240.9 kg ha-1) and Si concentration on leaves+1 (15.2 e 17.9 g kg-1 Si) and the least level of stalk borer incidence (3.7 e 5.8%) in first and second ratoons, respectively. The average of Si uptake by above ground dry mass of all varieties in ratoon crops were reduced to 44% from observed to plant cane The lowest Si concentration on TVD-leaves collected at 6 months was related with D. saccharalis incidence observed to IAC 94-4004.

Mori G.M.,University of Campinas | Zucchi M.I.,Polo Centro Sul | Sampaio I.,Federal University of Para | Souza A.P.,University of Campinas
BMC Evolutionary Biology | Year: 2015

Background: Mangrove plants grow in the intertidal zone in tropical and subtropical regions worldwide. The global latitudinal distribution of the mangrove is mainly influenced by climatic and oceanographic features. Because of current climate changes, poleward range expansions have been reported for the major biogeographic regions of mangrove forests in the Western and Eastern Hemispheres. There is evidence that mangrove forests also responded similarly after the last glaciation by expanding their ranges. In this context, the use of genetic tools is an informative approach for understanding how historical processes and factors impact the distribution of mangrove species. We investigated the phylogeographic patterns of two Avicennia species, A. germinans and A. schaueriana, from the Western Hemisphere using nuclear and chloroplast DNA markers. Results: Our results indicate that, although Avicennia bicolor, A. germinans and A. schaueriana are independent lineages, hybridization between A. schaueriana and A. germinans is a relevant evolutionary process. Our findings also reinforce the role of long-distance dispersal in widespread mangrove species such as A. germinans, for which we observed signs of transatlantic dispersal, a process that has, most likely, contributed to the breadth of the distribution of A. germinans. However, along the southern coast of South America, A. schaueriana is the only representative of the genus. The distribution patterns of A. germinans and A. schaueriana are explained by their different responses to past climate changes and by the unequal historical effectiveness of relative gene flow by propagules and pollen. Conclusions: We observed that A. bicolor, A. germinans and A. schaueriana are three evolutionary lineages that present historical and ongoing hybridization on the American continent. We also inferred a new evidence of transatlantic dispersal for A. germinans, which may have contributed to its widespread distribution. Despite the generally wider distribution of A. germinans, only A. schaueriana is found in southern South America, which may be explained by the different demographic histories of these two species and the larger proportion of gene flow produced by propagules rather than pollen in A. schaueriana. These results highlight that these species responded in different ways to past events, indicating that such differences may also occur in the currently changing world. © 2015 Mori et al.; licensee BioMed Central.

Laurie C.,University of Alabama | Wang S.,North Carolina State University | Carlini-Garcia L.A.,Instituto Agronomico Of Campinas | Carlini-Garcia L.A.,Polo Centro Sul | Zeng Z.-B.,North Carolina State University
BMC Genetics | Year: 2014

Background: How to map quantitative trait loci (QTL) with epistasis efficiently and reliably has been a persistent problem for QTL mapping analysis. There are a number of difficulties for studying epistatic QTL. Linkage can impose a significant challenge for finding epistatic QTL reliably. If multiple QTL are in linkage and have interactions, searching for QTL can become a very delicate issue. A commonly used strategy that performs a two-dimensional genome scan to search for a pair of QTL with epistasis can suffer from low statistical power and also may lead to false identification due to complex linkage disequilibrium and interaction patterns. Results: To tackle the problem of complex interaction of multiple QTL with linkage, we developed a three-stage search strategy. In the first stage, main effect QTL are searched and mapped. In the second stage, epistatic QTL that interact significantly with other identified QTL are searched. In the third stage, new epistatic QTL are searched in pairs. This strategy is based on the consideration that most genetic variance is due to the main effects of QTL. Thus by first mapping those main-effect QTL, the statistical power for the second and third stages of analysis for mapping epistatic QTL can be maximized. The search for main effect QTL is robust and does not bias the search for epistatic QTL due to a genetic property associated with the orthogonal genetic model that the additive and additive by additive variances are independent despite of linkage. The model search criterion is empirically and dynamically evaluated by using a score-statistic based resampling procedure. We demonstrate through simulations that the method has good power and low false positive in the identification of QTL and epistasis. Conclusion: This method provides an effective and powerful solution to map multiple QTL with complex epistatic pattern. The method has been implemented in the user-friendly computer software Windows QTL Cartographer. This will greatly facilitate the application of the method for QTL mapping data analysis.

Chagas R.C.S.,Federal University of Minas Gerais | Muraoka T.,University of Sao Paulo | Korndorfer G.H.,Federal University of Uberlandia | de Camargo M.S.,Polo Centro Sul
Bioscience Journal | Year: 2016

Although silicon (Si) fertilization in rice (Oryza sativa) plants have already been studied, most of the Brazilian studies have focused on the acidity correction effects of sources and the application rate, but not on Si supply. Moreover, beneficial effects are rarely linked to other Si-accumulation plants such as pearl millet (Pennisetum glaucum), which is extensively grown in low soluble Si of Cerrado soils. The objective of this study was to evaluate the Si sources and application rates on the yield and quality of two commonly cultivated grain crops (rice and pearl millet) in Cerrado soils. The experiments were conducted on two crops (rice and pearl millet) and two soil types (Rhodic Haplustox-LV and Quartzipsamment-RQ) in a completely randomized factorial scheme with four replicates, four Si rates (0; 200; 400, and 800 kg ha-1 Si); and three sources (calcium and magnesium silicate, wollastonite, and silicic acid). All plots received the same quantities of Ca and Mg to equilibrate these levels in both soils. Ca and Mg silicate and wollastonite produced linear increases in soluble Si (0.5 mol L-1 acetic acid), in LV, RQ, and in Si uptake by rice and pearl millet. Increases in shoot dry weight were observed in rice and pearl millet from maximum rates of 542, 550 and 480 kg ha-1 Si in RQ, respectively. Ca and Mg silicate levels were higher than wollastonite in the dry weight of both plants. © 2016, Universidade Federal de Uberlandia. All rights reserved.

de Camargo M.S.,Polo Centro Sul | Rocha G.,R. Diacono Jair de Oliveira | Korndorfer G.H.,Federal University of Uberlandia
Revista Brasileira de Ciencia do Solo | Year: 2013

Sugarcane is considered a Si-accumulating plant, but in Brazil, where several soil types are used for cultivation, there is little information about silicon (Si) fertilization. The objectives of this study were to evaluate the silicon availability, uptake and recovery index of Si from the applied silicate on tropical soils with and without silicate fertilization, in three crops. The experiments in pots (100 L) were performed with specific Si rates (0, 185, 370 and 555 kg ha-1 Si), three soils (Quartzipsamment-Q, 6 % clay; Rhodic Hapludox-RH, 22 % clay; and Rhodic Acrudox-RA, 68 % clay), with four replications. The silicon source was Ca-Mg silicate. The same Ca and Mg quantities were applied to all pots, with lime and/or MgCl2, when necessary. Sugarcane was harvested in the plant cane and first- and second-ratoon crops. The silicon rates increased soil Si availability and Si uptake by sugarcane and had a strong residual effect. The contents of soluble Si were reduced by harvesting and increased with silicate application in the following decreasing order: Q>RH>RA. The silicate rates promoted an increase in soluble Si-acetic acid at harvest for all crops and in all soils, except RA. The amounts of Si-CaCl2 were not influenced by silicate in the ratoon crops. The plant Si uptake increased according to the Si rates and was highest in RA at all harvests. The recovery index of applied Si (RI) of sugarcane increased over time, and was highest in RA.

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