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Permanhani M.,Federal Rural University of Rio de Janeiro | Vasconcellos M.A.S.,UFRuralRJ | De Souza R.T.,Pesquisador da Embrapa Uva e Vinho | Martelleto L.A.P.,UFRuralRJ
Revista Brasileira de Fruticultura | Year: 2014

Aiming to establish a mathematical model to estimate accurately the leaf area of Niagara Rosada in the region of Cardoso Moreira-RJ, this study was held in a particular vineyard Pioneiro Ranch, installed in 2002, in trellis system. It was collected randomly in the production cycle started in 2011, 70 leaves of various sizes, and completely expanded without apparent harm to determine the relationship between the leaf area (LA) and the area of the circle (CA), considering their diameter equal to the width of the leaf. By means of regression analysis, we obtained the linear equation (LAes = 0.82 * CA + 16.12) which together with two more were used to compare the leaf area estimated by measuring the leaf area of 30 leaves from the last cycle production (March 2012). It was found that the equations presented to estimate accurately the leaf area of ‘Niagara Rosada / IAC 572’ conducted in trellis system, in the region of Cardoso Moreira-RJ, with only one leaf dimension: the average width of the leaf, and the regress n model obtained (LAes = 0.82 * CA + 16.12) was the least underestimated leaf area compared (regression coefficient = 0.99), followed by the model indicated by Pedro Jr. et al. (1986). © 2014, Sociedade Brasileira de Fruticultura. All rights reserved.

Macedo R.,Embrapa Arroz e Feijao | Tarre R.M.,UFRuralRJ | Ferreira E.,UFRuralRJ | Rezende C.P.,CEPLAC | And 6 more authors.
Scientia Agricola | Year: 2010

A key contribution to study the cycling of nutrients in soil/plant/animal systems is the evaluation of the consumption of forage and their nutrients by cattle. The objective of this study was to test techniques to evaluate faecal production, in vitro digestibility, forage consumption and the proportion of legume in the acquired diet. Five Zebu steer calves were confined and fed five diets of different combinations of Brachiaria dictyoneura and Desmodium ovalifolium. All quantities of faeces were collected per animal and these values were found to compare favourably with those derived from using the chromium oxide technique. In vitro digestibility ranged from 7 to 10% higher than the actual in vivo digestibility. Faecal samples from steers fed with diets with 25% or more of grass in the mixture were found to be depleted in δ13C between 1.7 and 2.1‰, but no depletion was observed when the diet was 100% D. ovalifolium. There was a positive linear regression (r2 = 0.97***) of the δ13C of the diet with the δ13C of faeces, but if the acquired diet contained a very high proportion of legume, the legume content could be underestimated by as much as 10%. None of the internal indicators, such as lignin or ash content of the diets, were useful to predict feed intake, but the chromium oxide external indicator performed satisfactorily. The 13C analysis of the faeces was an effective predictor of the proportion of the legume in the consumed diet.

Santos C.A.B.,UFRuralRJ | Zandona S.R.,UFRuralRJ | Espindola J.A.A.,Embrapa Agrobiologia | Guerra J.G.M.,Embrapa Agrobiologia | Ribeiro R.L.D.,UFRuralRJ
Horticultura Brasileira | Year: 2011

The effect of soil mulch with different plant species was evaluated in relation to the performance of organically grown carrots and to weed population levels. The experiment was carried out at the Integrated Agroecological Production System located in Seropédica, Metropolitan Region of Rio de Janeiro State (Baixada Fluminense), Brazil, using a randomized blocks design comprising four treatments replicated six times. These treatments consisted of soil mulch with chopped and dried above-ground biomass of Cameroon grass (Pennisetum purpureum), gliricidia (Gliricidia sepium), and pigeon pea (Cajanus cajan) compared to uncovered plots (control treatment). Carrot marketable yield and root characteristics (weight, length, and major diameter) were determined at harvesting. Reinfestation by weeds was estimated through the total number of individuals per square meter of cultivated area and the assessment carried out at 20, 50 and 80 days after sowing. Carrot (cv. Brasília) showed significantly increased values regarding all the variables (except for root length) in the plots treated with legume amendments (pigeon pea and gliricidia). As for the Cameroon grass mulch, results were statistically equivalent to the control treatment. Weed populations by cultivated area unit reached levels up to 300% higher in the non-mulch plots compared to the ones covered with plant residues.

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