Embrapa Hortalicas

Brasília, Brazil

Embrapa Hortalicas

Brasília, Brazil
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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.

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.

Santos C.A.F.,Embrapa Semiarido | Da Costa D.C.C.,Embrapa Semiarido | Da Silva W.R.,Embrapa Semiarido | Boiteux L.S.,Embrapa Hortalicas
Crop Science | Year: 2012

Genetic parameters, heritability, and minimum number of genes for total seed protein content were estimated in tropical semiaridadapted cowpea [Vigna unguiculata (L.) Walp.] germplasm aiming to provide the basis for the development of cultivars with higher nutritional value. Generation mean and variance analyses were conducted with the parental lines, F1, F2, and backcross populations derived from two contrasting crosses 'IT97K-1042-3' (31.15% total seed protein content) × 'BRS Tapaihum' (24.35%) and IT97K-1042-3 × 'Canapu' (22%). Narrowsense heritabilities were moderate (47.7%) in the cross IT97K-1042-3 × BRS Tapaihum and high (87.6%) in the cross IT97K-1042-3 × Canapu. The analyses indicated (in both crosses) the importance of additive gene effects and the parental mean for total seed protein. The minimum gene number, estimated by different methods, ranged from three to seven in the IT97K-1042-3 × Canapu cross and three to less than 25 in the IT97K-1042-3 × BRS Tapaihum cross. Transgressive segregation was observed in the F2 population from the cross IT97K-1042-3 × Canapu, with individual plants displaying up to 34.1% seed protein content. The results suggest that, although under polygenic control, the seed protein content in cowpea can be improved via standard breeding methods largely used in selfpollinated crops. © Crop Science Society of America.

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.

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.

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.

Bacterial wilt, induced by the soil pathogen Ralstonia solanacearum, is a serious tomato disease in tropical countries in areas subject to high temperatures and high humidity. Disease control is very difficult and requires a set of management measures, among them grafting, which has become more popular after the release of a set of commercial tomato resistant rootstocks. Although protection conferred by these rootstocks has been effective in many locations, it is not enough under situations very conducive to bacterial wilt, such as high populations of the pathogen in the soil, high temperature, high soil humidity and presence of an aggressive strain of the pathogen. The objective of this work was to assess the potential of accessions of two Solanum species known as “jurubeba” in Brasil, as rootstocks to protect tomato plants against bacterial wilt through grafting. In experiments carried out under greenhouse conditions in Brasilia, 26 accessions of each Solanum scuticum and S. stramonifolium were tested. In a first phase, the set of accessions were challenged with one isolate of R. solanacearum previously known by its high virulence to solanaceous crops. In a second phase, three representative resistant accessions were challenged with three isolates of the pathogen also previously chosen for their high virulence to tomato and sweet pepper and distinct biovar/phylotype. Accessions of S. scuticum reacted differently to the pathogen’s isolates, but 15 out of 26 accessions presented an immune-like resistance to all bacterial isolates. No correlation was observed between resistance and origin of the accessions. S. stramonifolium accessions, differently from S. scuticum, were all resistant to the bacterial isolates. The two species of “jurubeba”, therefore, contain accessions that are higly resistant to a range of virulent isolates of R. solanacearum. Their use as rootstocks to protect tomato against bacterial wilt is viable, but further research is needed to solve eventual problems related to the rootstock-scion compatibility. © 2016, Sociedade de Olericultura do Brasil. All rights reserved.

The effect of line spacing and harvest time on carrot and Cenourete®, a baby carrot-like product, yield were evaluated under conditions of Central Brazil winter. Seeds were sown in order to obtain 6, 8 and 10 lines/meter, what corresponded to a distance of 16.6, 12.5 and 10 cm between lines, respectively. Harvests were made 80, 90 and 100 days after sowing. The cultivars grown were open-pollinated Esplanada and hybrid Sugar Snax 54. Root and Cenourete® yield varied with all the main factors and no interaction was significant. The root yield of both cultivars increased with later harvest at each density level. Yield of Esplanada root was only marginally affected by line spacing. Although significant, the effect of plant density on the yield of SugarSnax 54 accounted for less than 5% of the variation in the data set and differences between means were not significant by Tukey (α= 0.05). Cenourete® yield from Esplanada cultivar varied from 9.4±3.9 to 15.2±6.5 t/ha and from SugarSnax 54 it varied from 9.9±3.9 to 18.2±6.5 t/ha, depending on treatment. Anticipating harvest had a much greater effect in enhancing the recovery of Cenourete® from carrot roots than increasing plant density. Although it didn't affect total yield, decreasing line spacing to 10 cm was important to assure that a larger proportion of thinner roots were produced and consequently the production of superior quality Cenouretes® was higher. Harvest time was also important to determine the Cenourete® size since the increase in total production at later harvest was due to a higher proportion of larger Cenouretes®. The best combination line spacing x harvest time for Esplanada and SugarSnax 54 under the conditions of this experiment will depend whether the interest lies in the production of any or of a particular Cenourete® size.

Cabral C.S.,University of Pernambuco | Reis A.,Embrapa Hortalicas
Tropical Plant Pathology | Year: 2013

Fusarium wilt caused by Fusarium oxysporum f. sp. lactucae (FOLAC) is one of the most important problems for lettuce growers because it causes major losses in production. To identify cultivars with potential for use in the management of the disease, 102 accessions were evaluated for resistance to isolates of race 1 of FOLAC. Initially, preliminary screening was done, using the isolate Fus- 173. Then, 47 materials selected as highly resistant and a susceptible control (Regina) were reevaluated for resistance to other isolates of FOLAC race 1 from different locations: Fus-202 and Fus-205, in October 2011, Fus-219 and Fus-222, in November 2011; and Fus-207, Fus-209, and Fus-220 in December 2011. Inoculation was performed on 25 day old seedlings in the greenhouse by the method of cutting the roots and immersing them in the conidial suspension. The evaluation was performed using a scale ranging from 0 (healthy plant) to 4 (dead plant). Resulting data was transformed into a disease index and submitted to an analysis of variance and means comparison by the Tukey test (P=0.05). Thirty-two accessions were identified with wide resistance spectrum to different isolates of the pathogen in the four periods of inoculation. © by the Brazilian Phytopathological Society.

Correia N.M.,Embrapa Hortalicas | Gomes L.J.P.,São Paulo State University
Pesquisa Agropecuaria Brasileira | Year: 2015

The objective of this work was to evaluate soybean oversowing with Urochloa ruziziensis, for the soybean capacity of dry mass production, for weed infestation, and corn crop development under no-tillage system. The experiment was carried out in a randomized complete block design, with four replicates, in a 2 x 5 + 1 factorial arrangement. Oversowing with U. ruziziensis was evaluated in two soybean growth stages (R6

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