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Brasília, Brazil

Potato seed tubers in Brazil are commercialized in different sizes as determined by the Ministry of Agriculture, Livestock and Food Supply. The sizes are classified in types, which vary from type 0 (zero), tubers above 60 mm, up to type V, tubers below 23 mm. In this work, we evaluated the influence of seed tuber size on the incidence of bacterial wilt on cultivars Agata, BRS Ana, Asterix, and Bintje, grown in a field naturally infested with Ralstonia solanacearum, in Brasilia, Brazil. We used small, medium and large tubers, measuring in average 30, 50 and 90 mm, which correspond respectively to types IV, II and 0 according to the Brazilian legislation. Significant differences in bacterial wilt incidences were detected among cultivars: BRS Ana and Asterix did not differ from each other and were more resistant than Agata and Bintje, which formed a statistically homogeneous pair. Differences on the seed tuber size and interactions between cultivars and tuber size were not significant. Therefore, the seed tuber size, within the limits covered in this paper, have no effect on disease incidence in field screening for potato resistance to the bacterial wilt. Source

The population dynamics of South American tomato pinworm Tuta absoluta (Meyrick) (Lep.: Gelechiidae) affected by several mortality biotic factors such as predators, parasitoids and water (irrigation and raining). The objective of the present work was to quantify the role of each factor in the survivorship of tomato pinworm eggs. The experiments were conducted at Embrapa Hortaliças from 01/08/2004 to 07/11/2005 in tomato and tomato-coriander organic system and traditional tomato crop system. The following methodology were conducted: 1) tomato pinworm eggs were collected in the field at different stages of the crop cycle and incubated in laboratory until the caterpillar/parasitoid emergency; 2) tomato pinworm eggs were marked and recollected after 72 hours, as sentinel prey; 3) cohorts of tomato pinworm eggs were marked and monitored each 24h until caterpillar eclosion. The eggs collected in the field and kept in the lab showed greater mortality by Trichogramma sp. (32%) than those kept in the field (methodology 2 and 3). However, under field conditions (method 2 and 3) by Trichogramma sp. was as lower as 12%, and mortality caused by predator and water effects reach 36%. This difference suggests that egg permanence in the field expose it to competition with predators and mortality caused by water effect, decreasing the recruitment of Trichogramma sp. Egg parasitoids, generalist predators associated with the water impact resulted in more mortality rates on eggs of T. absoluta in organic tomato cropping system. Source

Zsogon A.,University of Sao Paulo | Alves Negrini A.C.,Embrapa Hortalicas | Alves Negrini A.C.,Australian National University | Peres L.E.P.,University of Sao Paulo | And 2 more authors.
New Phytologist | Year: 2015

Summary: Bundle sheath extensions (BSEs) are key features of leaf structure whose distribution differs among species and ecosystems. The genetic control of BSE development is unknown, so BSE physiological function has not yet been studied through mutant analysis. We screened a population of ethyl methanesulfonate (EMS)-induced mutants in the genetic background of the tomato (Solanum lycopersicum) model Micro-Tom and found a mutant lacking BSEs. The leaf phenotype of the mutant strongly resembled the tomato mutant obscuravenosa (obv). We confirmed that obv lacks BSEs and that it is not allelic to our induced mutant, which we named obv-2. Leaves lacking BSEs had lower leaf hydraulic conductance and operated with lower stomatal conductance and correspondingly lower assimilation rates than wild-type leaves. This lower level of function occurred despite similarities in vein density, midvein vessel diameter and number, stomatal density, and leaf area between wild-type and mutant leaves, the implication being that the lack of BSEs hindered water dispersal within mutant leaves. Our results comparing near-isogenic lines within a single species confirm the hypothesised role of BSEs in leaf hydraulic function. They further pave the way for a genetic model-based analysis of a common leaf structure with deep ecological consequences. © 2014 New Phytologist Trust. Source

The rough handling during harvest and preparation for the market contributes to the high volume of postharvest losses observed for vegetables. Postharvest losses of vegetables may be either in quantity, when food is not consumed but discarded, or in quality, when the sensory, nutritional or microbiological quality is reduced even when the food is suitable for consumption. In order to improve the infrastructure for harvest and post-harvest handling of vegetables in small farms, Embrapa Vegetables recommended a low cost working station made of three equipment: a tarp packing house; a wheelbarrow and a sorting table. These equipments contribute for the maintenance of the vegetable quality by reducing biotic and abiotic stresses (such as heat, dew, rain, mechanical damage) during harvest and postharvest handling and consequently extends the shelf life and the time available for the farmer to market his product. Additional benefits are related to the rural worker health and the working efficiency. Benefits for the worker health include the reduction of exposure to the sun and reduction of work-related musculoskeletal disorders caused by heavy loads, repetitive movements and/or awkward positions. Higher working efficiency is due to the elimination of repetitive activities, less tiredness due to overloading of the musculoskeletal system, reduction of thermal discomfort and the possibility to keep working when it is raining. © 2016, Sociedade de Olericultura do Brasil. All rights reserved. Source

Santos C.A.F.,Embrapa Semiarido | Boiteux L.S.,Embrapa Hortalicas
Genetics and Molecular Research | Year: 2013

One strategy to mitigate human malnutrition in semi-arid areas is to increase the protein and mineral content of cowpea cultivars. Total seed protein, potassium, calcium, iron, zinc, and sodium contents were quantifed in elite cowpea lines, with the aim to develop cultivars that had improved levels of these nutrients. Eighty-seven F6 lines derived from 6 crosses were evaluated under rain-fed conditions in Petrolina, Brazil. Seed protein and mineral content were quantifed by the micro-Kjeldhal method and in an atomic absorption spectrophotometer, respectively. Statistical analyses were estimated for all traits, including grain yield. Signifcant differences were observed for all characteristics. Seed protein content ranged from 22.5 to 34.1%, potassium levels ranged from 20,200 to 27,000 ppm, and calcium levels ranged from 410 to 6260 ppm. Iron content ranged from 36.5 to 137 ppm, while zinc content ranged from 36 to 58 ppm and sodium content ranged from 29.2 to 88 ppm. Simple correlation coeffcient values indicated that selection for high protein and mineral content does not affect grain yield. These results demonstrate that it is feasible to obtain new biofortifed cowpea cultivars by combining higher levels of protein and essential minerals. © FUNPEC-RP. Source

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