Ana Maria Resende Junqueira

Acúmulo de nitrato em alface em função da adubação, horário de colheita e tempo de armazenamento

The experiment was carried out in Brasilia, Brazil, from January to March 2004, aiming to evaluate the level of nitrate in lettuce, cv. Veronica, as a result of fertilization, harvesting time and storage period (8oC). We used the ramdomized blocks experimental design in a factorial 5 x 4 x 4, with four replicates. The five fertilization treatments tested were: 1,5 kg m-2 of chicken manure (T1); 3,0 kg m-2 of cattle manure (T2); mineral, as a result of soil chemical analysis - M (T3); M with 1,5 kg m-2 of chicken manure (T4); and M with 3,0 kg m-2 of cattle manure (T5). The harvesting times were 7 and 11 a.m., and 3 and 6 p.m. The storage periods were 0; 3; 5 and 7 days. The treatments T1 and T4 resulted in plants with the highest levels of nitrate, 1240,12 and 1303,66 mg NaNO3 kg-1, respectivelly, while T2 resulted in the lowest nitrate level, 547,26 mg NaNO3 kg-1. However, when cattle manure was added to M (T5), an increase of 2,18 times was observed in the nitrate level (1195,25 mg NaNO3 kg-1). Plants harvested at 7 a.m. showed the lowest levels of nitrate, suggesting that it is the best moment to harvest lettuce in the Distrito Federal region. During the storage period of seven days, nitrate level was reduced by 29,3%.

Produtividade, florescimento prematuro e queima-das-folhas em cenoura cultivada em sistema orgânico e convencional

Four experiments were carried out with carrots genotypes during summer season in Distrito Federal, Brazil, to evaluate yield, bolting and leaf blight under organic and conventional conditions. The experiments were carried out in two locations and in each one two experiments were established, considering both crop systems. The experimental design was a random block with eight treatments and five replicates. The treatments consisted of the cvs. Alvorada, Brasilia RL, Brasilia Bionatur, Kuronan, Nantes 3 Tip Top, Carandai AG 106, Brazlândia and Pop. 0212246. The soil was fertilized with organic compost for the organic trial and with chemical fertilizer for the conventional trial. Plants were evaluated for leaf blight incidence, 70 days after sowing date, through visual observation. Roots were harvested 95 days after sowing, washed, classified and weighted. Bolting was more frequent in Brasilia Bionatur, under conventional condition, in Brazlândia. A difference of susceptibility to leaf blight among genotypes was observed in plants cultivated in the organic system. Nantes was the most susceptible while Pop. 0212246 was the most resistant. Alternaria dauci was observed more frequently at Brazlândia, while Cercospora carotae was observed at both locations, similarly, under organic conditions. For commercial and total yield, commercial and total root number, Pop. 0212246 and Brazlândia were the best materials in both crop systems. Total and commercial yield, total and commercial root number, number and weight of refused roots were higher in the conventional area, compared to the organic area. Brasilia and Brazlândia can be recommended for Distrito Federal, independently of crop system, during summer season. Pop. 0212246 showed desirable agronomical characteristics and can be, in the future, available for farmers in Distrito Federal.

Balanço nutricional e incidência de queima de bordos em alface produzida em sistema hidropônico - NFT

Aiming to evaluate the effect of nutrients balance in lettuce tip burn incidence, an experiment was carried out in Brasilia, Brazil, from October 2001 until June 2002, in two phases. During the first phase four solution concentrations (0.5; 1.5; 2.5 and 4.0 mS.cm-1) were evaluated to determine the concentration with the highest percentage of tip burn. During the second phase, a solution concentration of 4,0 mS.cm-1 and foliar applications of three calcium sources (CaCl2, CaB2® and CaNO3) were applied to plants to prevent tip burn. Nutritive solution proposed by Castellane and Araujo in 1995 was used in both phases. The evaluated parameters were percentage of plants with tip burn incidence, leaf nutrient concentration and plant fresh weight. In the first trial the more concentrated (4,0 mS.cm-1) and the less concentrated (0,5 mS.cm-1) nutritive solution presented the highest percentage of plants with the symptoms. In the second trial, the zinc deficiency induced by boron high concentration, was responsible for the symptoms. This was the reason why calcium leaf application was not effective on reducing foliar symptoms.

Populational survey of arthropods on transgenic common bean expressing the rep gene from Bean golden mosaic virus

Genetically modified (GM) crops is considered the fastest adopted crop technology in the history of modern agriculture. However, possible undesirable and unintended effects must be considered during the research steps toward development of a commercial product. In this report we evaluated effects of a common bean virus resistant line on arthropod populations, considered as non-target organisms. This GM bean line (named M1/4) was modified for resistance against Bean golden mosaic virus (BGMV) by expressing a mutated REP protein, which is essential for virus replication. Biosafety studies were performed for a period of three years under field conditions. The abundance of some species was significantly higher in specific treatments in a particular year, but not consistently different in other years. A regular pattern was not observed in the distribution of insects between genetically modified and conventional treatments. Data analyses showed that minor differences observed can be attributed to random variation and were not consistent enough to conclude that the treatments were different. Therefore the present study indicates that the relative abundance of species are similar in transgenic and non-transgenic fields.

Efeito da solarização e da adubação sobre artrópodes em solo cultivado com alface

To evaluate the effect of solarization, chemical and organic fertilization on soil arthropods community in lettuce, two blocks plots trials were carried out in Brasilia, Brazil. One research was conducted with solarization and the other without solarization in a soil cultivated with lettuce, cv Veronica, under protected cultivation. Each trial consisted of five fertilization treatments: T1= organic fertilization; T2= amoniacal nitrogen (ammonium sulphate); T3= chemical fertilization; T4= organic and chemical fertilization; T5= control (without fertilization). In the solarized trial, the soil was covered for 132 days with transparent plastic. The arthropods were collected by pitfalls at three moments: 1) before solarization, 2) after solarization and 3) at harvest. Faunistic indexes were calculated in each trial, treatment and moments. The main collected groups were: Collembola (82.8%), Acari (7.1%), Hymenoptera (6.1%), Coleoptera (1.3%) and others (2.7%). Collembola class represented the largest proportion of the arthropods, even at harvest when the sub-order Acari substantially increased. The predominant species of Collembola were: Proisotoma tenella (Reuter) (34.3%); Seira atrolutea (Arle) (29%); Folsomides centralis (Denis) (7.2%); Isotomurus sp.161 (2.4%) and Sminthurides sp. 98 (1.6%). Arthropods community was not affected by solarization or fertilization.

Produção hidropônica de alface cv. Verônica em diferentes substratos

In an experiment carried out between September and November 1997 at Fazenda Agua Limpa, Universidade de Brasilia, Brazil, growth and yield of lettuce cultivar Veronica were evaluated on three different substrates in a hydroponic system. The experimental design was a complete randomized block with three treatments: rice husk, gravel and pebble, with 25 replicates. After 62 days, plants were collected and plant and root weight, number of leaves and head diameter were evaluated. The younger leaves from plants from all treatments were also collected for macro and micronutrients analyses. Plants grown on rice husk showed significantly higher plant and root weight compared to those grown on gravel and pebble. No statistically significant difference was observed for plant and root weight in gravel and pebble treatments. Statistically significant differences between all treatments were observed on the basis of number of leaves and head diameter. Both parameters were higher in plants grown on rice husks, followed by gravel and pebble. No differences were observed in the absorption of macronutrients among treatments. However, plants grown on rice husk absorbed less zinc and copper than plants grown on gravel and pebble.In an experiment carried out between September and November 1997 at Fazenda Agua Limpa, Universidade de Brasilia, Brazil, growth and yield of lettuce cultivar Veronica were evaluated on three different substrates in a hydroponic system. The experimental design was a complete randomized block with three treatments: rice husk, gravel and pebble, with 25 replicates. After 62 days, plants were collected and plant and root weight, number of leaves and head diameter were evaluated. The younger leaves from plants from all treatments were also collected for macro and micronutrients analyses. Plants grown on rice husk showed significantly higher plant and root weight compared to those grown on gravel and pebble. No statistically significant difference was observed for plant and root weight in gravel and pebble treatments. Statistically significant differences between all treatments were observed on the basis of number of leaves and head diameter. Both parameters were higher in plants grown on rice husks, followed by gravel and pebble. No differences were observed in the absorption of macronutrients among treatments. However, plants grown on rice husk absorbed less zinc and copper than plants grown on gravel and pebble.

Normativa de Produção Orgânica no Brasil: a percepção dos agricultores familiares do assentamento da Chapadinha, Sobradinho (DF)

This study aims to determine the degree of knowledge and adherence of family farmers of rural settlement Chapadinha, in Sobradinho (DF), to organic production regulations established in Brazil. The research methodology used included open interviews that intended to assess the perceptions and knowledge of the producers on the most important regulations for organic production in Brazil: Law 10831/2003, Decree 6323/2007 and the Normative Instruction 46/2011; these standards had been integrated into three units of analysis: guidelines of systems and production, marketing processes and control mechanisms. The paper points out that the documentation is the biggest bottleneck in smallholder certification process, as these requirements are complex, and there is less training related to the proper understanding of these documents. In relation to the marketing process and control mechanisms it was identified that the producers have a degree of incomplete knowledge related to some of the rules of the parameters related to these aspects, damaging time for certification, requiring greater technical guidance and monitoring.

Efeito da adubação química na infestação do ácaro rajado e na produção do morangueiro

Effect of chemical fertilization on two-spotted-spider mite infestation and strawberry yield The effect of N:K relationship was evaluated when applied through fertigation, on two-spotted-spider mite, Tetranychus urticae, infestation and on the yield of two strawberry cultivars. Strawberry plants received weekly doses of N and K (g/plant) by drip irrigation: 0.27 and 0.13; 0.27 and 0.50; 0.27 and 0.76 and control (water+micronutrients). Fruits were collected twenty two times during crop cycle. Marketable, non-marketable fruits and other yield parameters were evaluated. Leaf nutrient content analysis was performed to determine the nutritional condition of the plants. Population density of T. urticae was evaluated weekly. A significant interaction between K doses and pest population was observed. Higher doses of the nutrient reduced the number of eggs and active forms of the pest population and the cultivar Diamante showed the smallest pest density. K and P showed negative correlation with both variables, but N showed a positive one. No effects were observed of fertilization on yield parameters due, probably, to the high mite infestation (>40 individuals per leaflet) in all treatments during most of the crop cycle. Solely the use of different N:K ratios on the strawberry fertilization management at this specific experimental condition, was not sufficient to control two-spotted spider mite nor to reduce losses caused by that pest.