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San Miguel de Tucumán, Argentina

Sorol N.,Estacion Experimental Agroindustrial Obispo Colombres | Arancibia E.,National University of Tucuman | Bortolato S.A.,National University of Rosario | Olivieri A.C.,National University of Rosario
Chemometrics and Intelligent Laboratory Systems | Year: 2010

Several variable selection algorithms were applied in order to sort informative wavelengths for building a partial least-squares (PLS) model relating visible/near infrared spectra to Brix degrees in samples of sugar cane juice. Two types of selection methods were explored. A first group was based on the PLS regression coefficients, such as the selection of coefficients significantly larger than their uncertainties, the estimation of the variable importance in projection (VIP), and uninformative variable elimination (UVE). The second group involves minimum error searches conducted through interval PLS (i-PLS), variable-size moving-window (VS-MW), genetic algorithms (GA) and particle swarm optimization (PSO). The best results were obtained using the latter two methodologies, both based on applications of natural computation. The results furnished by inspection of the spectrum of regression coefficients may be dangerous, in general, for selecting informative variables. This important fact has been confirmed by analysis of a set of simulated data mimicking the experimental sugar cane juice spectra. © 2010 Elsevier B.V.

Will A.,National University of Tucuman | Bustos J.,National University of Tucuman | Bocco M.,National University of Cordoba | Gotay J.,National University of Tucuman | Lamelas C.,Estacion Experimental Agroindustrial Obispo Colombres
Renewable Energy | Year: 2013

Prediction of climatic variables, in particular those related to wind and solar radiation, has developed a huge interest in recent years, mainly due to its applications to renewable energy. In many cases there is a large number of factors that influence the climatic variable of interest, and the researcher chooses the most relevant ones (based on previous knowledge of the region, availability, etc.) and runs a series of experiments combining the available data in order to find the combination that provides the best prediction.In this work we present two applications of Niching Genetic Algorithms to solve the problem of selection of variables for the estimation of Solar Radiation. On one hand, this methodology is able to estimate a given climatic variable using databases with missing data, since the algorithm can compensate it by the use of others. On the other hand, we present a methodology that allows us to select the relevant input variables for a given climatic variable estimation or prediction problem, in a systematic way, using the same Genetic Algorithm with different parameters.Both methods were tested in the estimation of daily Global Solar Radiation in El Colmenar (Tucumán, Argentina), using linear regression on data from 14 weather stations spread along the north of Argentina. The results obtained show that the methodology is appropriate, providing an RMSE = 2.36 [MJ/m 2] and R = 0.926 using an average of 64 out of 329 initial variables, on a 70 individuals/85 generations combination. For a 200 individuals/150 generations combination it obtained an RMSE = 2.34 [MJ/m 2] and R = 0.928 using an average of 54 variables. © 2012 Elsevier Ltd.

Cordeiro A.B.,Instituto Agronomico do Parana IAPAR | Sugahara V.H.,Instituto Agronomico do Parana IAPAR | Stein B.,Estacion Experimental Agroindustrial Obispo Colombres | Leite Junior R.P.,Instituto Agronomico do Parana IAPAR
Crop Protection | Year: 2014

Citrus variegated chlorosis (CVC), caused by the xylem-limited bacterium Xylella fastidiosa subsp. pauca (Xfp), is a damaging disease of sweet oranges (Citrus sinensis (L.) Osbeck) in several citrus production areas of South America. CVC was first identified in sweet orange orchards in the Northwest region of São Paulo State, Brazil. Transmission of Xfp from seed of CVC infected sweet orange fruit to seedlings has been reported. However, Xfp has not been reported to infect or cause CVC in lemon (Citrus limon (L.) Burm. f). Therefore, the objectives of this study were 1) to further evaluate the potential for vertical transmission of the bacterium through sweet orange seeds originating from symptomatic fruits to sweet orange seedlings and 2) to examine lemon trees and seeds for PCR detection of Xfp. Based on our evaluations, Xfp was not detected by PCR in leaves and seeds of different lemon cultivars surrounded by sweet orange orchards with high incidence of CVC. Furthermore, we could not detect with PCR that Xfp is vertically transmitted through sweet orange seeds to seedlings of sweet orange even from fruits with typical CVC symptoms. Hence, in this study and with the cultivars tested, Xfp was not confirmed by PCR detection to be transmitted via infected seeds from fruits of Citrus spp. even in areas where CVC is endemic nor was lemon found to be a natural host of Xfp. © 2014 Elsevier Ltd.

Lax P.,National University of Cordoba | Rondan Duenas J.C.,Laboratorio Of Biologia Molecular | Coronel N.B.,Estacion Experimental Agroindustrial Obispo Colombres | Gardenal C.N.,National University of Cordoba | And 2 more authors.
Crop Protection | Year: 2011

The existence of races within the species Nacobbus aberrans sensu Sher has been confirmed; however, there is no consensus on a consistent system for race determination. Four plant species previously used as differential hosts in some N. aberrans race tests (tomato, pepper, sugarbeet and potato) were tested for susceptibility to seven nematode populations from Argentina. Plants were inoculated with second-stage juveniles and kept under glasshouse conditions at 21 °C for 90 days. The parameters evaluated (root gall index, egg mass index, and reproduction factor) in different nematode populations and plants showed significant differences. The reproductive fitness of the nematode populations differed among the plants that showed some degree of susceptibility. The results showed that N. aberrans comprises populations differing in host preference. Based on the nematode populations' behaviour on these hosts, two groups were distinguished: i) populations that multiplied on all hosts, ii) populations that did not multiply on potato. The present work contributes to the analysis of criteria for developing a differential host test. © 2011 Elsevier Ltd.

Barrionuevo M.J.,Instituto Superior Of Entomologia Dr Abraham Willink | Murua M.G.,Estacion Experimental Agroindustrial Obispo Colombres | Murua M.G.,CONICET | Goane L.,Estacion Experimental Agroindustrial Obispo Colombres | And 3 more authors.
Florida Entomologist | Year: 2012

Rachiplusia nu (Guenée) and Chrysodeixis (= Pseudoplusia) includens (Walker) (Lepidoptera: Noctuidae) are 2 economically important species in soybean in northern Argentina. Life cycle, reproductive and population parameters of R. nu and C. includens reared on artificial diet were determined under controlled environmental conditions. Fecundity increased from d 2 to 3 with values of 67.6 eggs per female for R. nu and 75.7 eggs for C. includens. An average of 79.9% (R. nu) and 74.4% (C. includens) of individuals reached the larval stage and 71.1% (R. nu) and 71.4% (C. includens) of individuals reached the adult stage. The life expectancy (ex) curve showed 4 and 3 periods of mortality. The survivorship curves of the 2 species resembled the theoretical type I. Life table analysis determined that R. nu and C. includens have the potential to quickly increase their populations under controlled rearing conditions. These results provide important information that will be used to improve artificial rearing procedures contributing with biological studies towards to develop management programs of both species.

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