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Bastidas L.,Instituto Nacional Of Investigaciones Agricolas Inia Zulia | Geraud-Pouey F.,University of Zulia | Chirinos D.T.,University of Zulia | Romay G.,Institute Estudios Avanzados | Santana M.A.,Simon Bolivar University of Venezuela
Bioagro | Year: 2015

The begomovirus-Bemisia tabaci (Gennadius) complex is the main sanitary problem of tomatoes in Venezuela. Genotypes resistant to begomoviruses are a valuable alternative for integrated management of this problem. Consequently, it was assessed the performance of the cultivars Rio Grande (CRG), Alba El cid and Shan TY, the first one susceptible and the other three promoted as resistant to TYLCV. This virus, along with ToVEV, are two common tomato begomoviruses in Venezuela. Transmission assays mediated by B. tabaci were conducted to assess time for symptoms appearance and transmission efficiency. CRG showed TYLCV symptoms after 12.6 ± 1.2 days post inoculation (DPI) in 100 % of the plants, while for the remaining cultivars it ranged from 14.1 ± 1.3 to 16 ± 1.5 DPI with 18.5-33.3 % of symptomatic plants, generally with mild symptoms. With ToVEV for CRG, symptoms appeared at 12.4 ± 1.2 DPI with 100 % of affected plants, and for the other cultivars more than half of the plants (ranging 66.7 to 81.5 %) showed symptoms at 12 ± 1.1 to 14.9 ± 1.4 DPI. El Cid showed the most severe symptoms. In all plants exposed to begomovirus, viral DNA was detected by PCR. The resistance to a begomovirus can provide some resistance to another but not to all of them. However, those that showed tolerance could be utilized to reduce the effect of these begomoviruses on tomato crops in Venezuela. © 2015, Universidad Centroccidental Lisandro Alvarado (UCLA). All rights reserved.

Gonzalez I.,Instituto Nacional Of Investigaciones Agricolas Inia Zulia | Betancourt M.,Instituto Nacional Of Investigaciones Agricolas Inia Zulia | Fuenmayor A.,Instituto Nacional Of Investigaciones Agricolas Inia Zulia | Lugo M.,Instituto Nacional Of Investigaciones Agricolas Inia Zulia
Zootecnia Tropical | Year: 2011

The objective of the investigation was to evaluate the effect of cultivar and the age of maturity or harvest on the chemical composition and the yield in two species of Grass elephant Pennisetum sp. (Green and Purple), under conditions of very dry tropical forest West of Venezuela. The experiment was carried out in a cultivated area of approximately one year of established, sowed in arrays to 1,00 m of separation, of which an experimental area of 1.170 m2 (90 × 13) was selected, for the investigation. The experimental design was factorial 5 × 2, with 2 cultivars and 5 ages of maturity or it harvests (14, 28, 42, 56 and 70) days, with three repetitions, to measure its effect on the partially dry matter variable (MS), gross protein (PB), fiber neutral detergent (FND), fiber acid detergent (FAD), lignina acid detergent (LAD), ash (CZ), yield of green matter (RMV) and yield of dry matter (RMS). High potentiality of production of biomass was observed for both cultivars, of which cultivating green elephant resulted superior with a (P<0,01) cultivating green elephant with yields averages of 10,2 t/ha MS, while the best values (17,1%) in PB were contributed by cultivating lived elephant. For the components alone cellular wall there was answer for FND with values of 55,7% for cultivating green elephant. The parameters of chemical composition and yield increased with the age of maturity, while the protein contents and ash diminished. The grass elephant (Pennisetum sp) like court grass, show a high potential for the production and quality of biomass, however as any tropical grass, it reduces their nutritious value with the age of maturity, that which requires of the establishment of handling strategies for their efficient use during the year.

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