Please read the abstract in the dissertation / Dissertation (MSc (Agric))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Effects of electrostatic fields on insects were studied using cabbage loopers, Trichoplusia ni (Hubner) and houseflies, Musca domestica L. Two series of tests were conducted; one to determine the electrostatic field effect on the locational preference and the other to determine the field effect on wingbeat. Among the field gradients examined (250, 500, 750, 1000, 1250, 1500 v/crn), those with 750 v/cm and up had significant influence on the locational preference of houseflies at the five percent significance level. With a choice between two regions, having no field and with field at an e.f.i. of 750 v/cm, houseflies preferred to be in the field. For gradients above 750 v/cm the houseflies preferred the region with no field. Electrostatic fields with gradients 500, 750, 1000, 1250, and 1500 v/cm had significant effect on the wingbeat frequency of male cabbage loopers and no effect on females. The change in wingbeat among males was found to increase linearly with increasing e.f.i. Removal of part or full antenna did not effect the response of loopers to electrostatic fields. / Master of Science

Downy mildew of broccoli, cabbage, and cauliflower is caused by the plant pathogenic fungus Peronospora parasitica. Cool damp weather with high humidity is highly favorable for sporulation, dissemination of spores, and infection by this pathogen. The severity of disease is affected by the duration of these weather conditions favorable for disease development. Potential new fungicides were evaluated for disease control in a field trial conducted in the winter of 1992-93. For broccoli, no significant differences in disease severity were detected among treatments. On the other hand, Microthiol and Microthiol + Maneb significantly reduced the number of downy mildew lesions on cabbage and cauliflower compared to nontreated plants. Maneb alone provided significant disease control on cabbage, but not on cauliflower.

Cabbage is one of the most important and widely grown crops in KwaZulu-Natal (KZN). In cabbage production, no clear cropping methods exist (other than succession cropping) to allow the soil to recover its fertility status naturally after the harvested has crop absorbed nutrients from the soil. Succession cropping system is extensively practiced by cabbage farmers. Succession cropping is when a succeeding vegetable crop is planted immediately after harvesting the preceding crop. This does not allow soil fertility status to be balanced by soil microbes in an environmentally friendly approach. Instead, synthetic fertilizers are heavily used to rectify soil fertility status and these have negative impacts on the soil in the long term, followed by yield decline. However, the economic downturns and green environment awareness have caused researchers and some farmers to focus more on developing environmentally healthy crop production technologies. A priority in this study was to elucidate effects of cover crops-green manure as rotational crops in cabbage production. The experimental site is located at Cedara Research Station. In 2009, soil samples were taken from the top 30 cm of the soil profile, in a zigzag pattern in 5 m x 5 m grids for fertility analysis. Results were used to determine nutrient deficiencies, and blanket application of phosphorus and potassium followed according to each grid’s deficiency. The study was divided into two cycles, with each cycle consisting of season one and season two. The study was conducted over a two year period. Cycle one, season one, 2009/2010 (Dec-Mar): four treatments (sunn hemp: planted at 50 kg/ha seeding rate; forage sorghum: planted at 50 kg/ha seeding rate; mixture of sunn hemp-forage sorghum: each planted at 25 kg/ha seeding rate and control: cabbage planted at 30 cm within rows x 60 cm between rows) were used. The statistical design of the study was a 4x4 Latin Square experiment repeated twice in adjacent fields (347 m2 each) 6 m apart, with a total of 32 plots. Each experimental plot was 8.5 m x 9 m. Genstat Package, 9th Edition was used for data analysis. Standard cabbage production recommendations were followed in control treatments. Cabbage yield was determined in all control plots. Weed coverage percentages were determined in all four treatments. Cycle one, season two, 2010, (Apr-Aug): all 32 plots from season one were each split into four, in a Split Plot design, resulting in a total of 128 plots in both fields. Nitrogen was applied at four different levels: 0, 80, 160 and 240 kg N/ha. Standard cabbage production methods were followed again as in the control treatment in season one. Cover crops were replaced by planting cabbage. Cabbage was repeated in the control plots. Cabbage yield, cabbage leaf nutrients, soil nitrate and ammonium nitrate and soil carbon to nitrogen (C:N) ratio were measured. Cycle two, season one, 2010 (Sep-Dec): The same method in cycle one, season one was repeated. Cycle two, season two, 2010/2011, (Dec-Apr): The same method in cycle one, season two was repeated. Although in this study there was visibly a large amount of residues left over after the trial was harvested, the use of a tractor-drawn slasher was not very effective. The slashed material was not chopped into smaller pieces, as it would if a roll-chopper had been used. A tractor-drawn slasher was used because it is a tool available to many farmers. As a result, it was not a simple process to transplant seedlings mechanically, due to the amount of organic matter that was in the soil after it had been incorporated. The mechanical planter pulled off, removed and became blocked by the residues, and as a result it was not able to operate as it would in normal soils. The residues removed soil from the furrows and that caused seedlings to fall over as all the soil for the root system support had been moved by the planter and stuck residues. The planter had to be assisted by hand planting seedlings that were not properly planted mechanically. Hence, from the operational perspective, the choice of tools for chopping were not effective in this study and this is something to be considered in future studies, where it will be necessary to compare different tools for planting and cover crop incorporation into the soil. During the present study, soil N content in different plots had significant differences (P=0.05). The control showed high levels of total N content, but this was not related to the low yields exhibited by cabbage after cabbage at all levels of N. Since, where there were cover crops, the N content was low, this could mean that N was immobilized, compared to the cabbage treatments where plenty of N was available. Immobilized N is thus not available for leaching, polluting the environment. The yield of cabbage was significantly lowest in controls. The study showed that cover crop-green manure use has a positive effect in terms of yield improvement. The cabbage yields from the sunn hemp plots at a 0 kgN/ha were significantly different from the yield of cabbage planted following cabbage at 240 kgN/ha N. The study also showed that N is not the only yield determinant in cabbage production. Too much N has a tendency to suppress cabbage yields. The cover crop-green manures selected for this study were shown to be ineffective in suppressing weeds. This was true even though the weed coverage percentage in each of the cover crop-green manure plots was above 65%, except for the cabbage crop. This study did not separate different weeds, but the most dominant weeds were Amaranthus hybridus (pigweed), Galinsoga parviflora (gallant soldier), Bidens pilosa (common blackjack) and Cyperus esculentus (yellow nutsedge). These weeds were effectively controlled in the cabbage sole crop by the use of herbicides and mechanical weeding. The result of cover crop-green manures not suppressing weeds was significantly associated with the cover crop-green manure seeding rate. This study has been a starting point in the development of cover crops-green manure as rotational crops in cabbage production. It is concluded that cover crop-green manure (sunn hemp and forage sorghum) used in this study for vegetable (cabbage) production has proven to be successful in improving yields. Yields obtained from cover crop-green manure treatments were better than yields obtained from - conventional tillage methods for cabbage production (control). However, in cabbage, weed suppression and soil N content, failed to improve significantly in response to the cover crop green manures used. The high plant population density under a cover crop, combined with weed population, may lead to high uptake of soil N for plant growth, leaving less N in the soil and in the plant. In the sole cabbage crop, because of low competition, there was adequate uptake of N for plant growth and yet the crop was not exhaustive of soil N. Further research is required in the following areas: comparison of cabbage with other vegetable crops in response to the effect of the selected cover crops; comparison of mechanical weeding and herbicide use as means of controlling weeds during cover crop-green manure growth; identification of dominant weeds in the presence and absence of cover crops, and monitoring of soil water relations and other fertiliser effects. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Tikslo įgyvendinimui buvo atlikta baltagūžių ir mėlynųjų kopūstų bei saldžiųjų raudonųjų ir geltonųjų paprikų fermentacija skirtingomis pieno rūgšties bakterijomis (PRB) (L. sakei, P. pentosaceus KTU-08, P. pentosaceus KTU-09 ir P. acidilactici). Tiriant fermentacijos proceso efektyvumą buvo įvertinta pH dinamika, gautuose produktuose nustatytas PRB kolonijas sudarančių vienetų skaičius grame produkto (KSV/g), L (+) ir D-(-) pieno rūgšties izomerų kiekis, atlikta juslinė analizė, priimtiniausiems produktams įvertintos spalvų koordinatės ir tekstūros savybės. Pagal gautus tyrimų rezultatus galima teigti, kad eksperimente naudotos PRB yra tinkamos baltagūžių ir mėlynųjų kopūstų bei saldžiųjų raudonųjų ir geltonųjų paprikų fermentacijai. PRB taikymas daržovių fermentavimui yra efektyvus, nes į smulkintas daržoves įterpus PRB, jos kurį laiką dominuoja. Naudojant fermentacijai PRB, gaunamas pakankamai žemas produktų pH, o tai suteikia fermentuotoms daržovėms priimtinas vartotojams juslines savybes. Daržovių fermentacijai taikant PRB, gaunami didesnio šviesumo, raudonumo, geltonumo, grynumo bei spalvos tono produktai. Siekiant užtikrinti fermentuotų produktų saugą D(-) pieno rūgšties izomerų aspektu daržovių fermentacijai reikėtų rinktis L. sakei. / Fermentations with different lactic acid bacteria (LAB) (L. sakei, P. pentosaceus KTU-08, P. pentosaceus KTU-09 and P. acidilactici) of white cabbage, red cabbage, sweet red and yellow paprika were performed in order to achieve the goal. While studying the effectiveness of the fermentation process, pH dynamics was evaluated, colony forming units of LAB in fermented products, concentration of lactic acid isomers L (+) and D(-), sensory analysis, colour coordinates and texture parameters were evaluated. We conclude that in the experiment used LAB are suitable for the fermentation of a white cabbage, red cabbage, sweet red and yellow paprika. The application of LAB is effective, because LAB were dominate for some time in the fermented vegetables. While using LAB for the vegetables fermentation, pH was found quite low, and improve sensory properties of the fermented vegetables products. LAB gives higher brightness, clarity of red and yellow, as well as colour tone of the fermented products. In order to ensure the safety of fermented products, in the context of D (-) lactic acid, L. sakei would be more suitable for the vegetable fermentation.

The seasonal abundance of the imported cabbageworm, <i>Artogeia rapae</i> (L.)), cabbage looper <i>Trichoplusia ni</i> (Hubner)) and diamondback moth (<i>Plutella xylostella</i> (L.)) was determined in 1982 to 1984 on cabbage in southwest Virginia. The imported cabbageworm was the most important pest. It had one and a partial second generation in 1982 and 1983, and two and a partial third generation in 1984. Market Prize and Green Winter varieties had lower <i>A. rapae</i> infestations than Abbott & Cobb #5 or Rio Verde. Two generations of the diamondback moth, which preferentially fed on cabbage leaves versus heads, were seen in 1983 and 1984. <i>Diadegma insularis</i> (Meus.) (Hymenoptera: Ichneumonidae) parasitized 46% and 69% of the diamondback moth in 1983 and 1984, respectively. Higher parasitization of <i>P. xylostella</i> was found in pupae collected from Abbott & Cobb #5. Two generations of the cabbage looper were seen in 1983 and a single generation in 1984. <i>Pteromalus puparum</i> (L.) (Hymenoptera: Pteromalidae) parasitized 64.1% and 32.5% of imported cabbageworm pupae in 1983 and 1984; parasitism was most pronounced in the latter part of the season. High percentages of parasites successfully emerged as adults, indicating efficient host utilization. Most parasite mortality within the host occurred in the larval stage; mean adult parasite emergence per host for 1983 and 1984 was 52.3 with a 1:1 sex ratio. <i>P. puparum</i> parasitized either host sex, producing equal proportions of male and female parasites. Adult female <i>P. puparum</i> were not adversely affected by residues of methomyl (Lannate®), permethrin (Pounce®) and fenvalarate (Pydrin®), but males showed significantly higher mortality than controls following exposure to methomyl after 12 h, and methomyl and permethrin after six days. <P. puparum</i> adults were successfully refrigerated for up to 15 days at 3°C in individual gelatin capsules. Survival beyond 15 days was better at l5°C and 23°C. <i>A. rapae</i> larvae could be reared at densities of 30 to 60 larvae per 70±10 g on a high wheat germ artificial diet. Pupae from the lowest density were larger in length and weight than those reared at the two higher densities, and all laboratory-reared pupae were smaller than either normal or parasitized field pupae. / Ph. D.

The diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), is a cosmopolitan insect pest of Brassica crops. In South Africa, there are no action thresholds for its chemical control which makes it difficult for growers to make informed decisions on when to apply insecticides and how frequently to apply them in order to achieve optimal crop yield. To contribute towards optimum application of insecticides against P. xylostella, this study compared the impact of weekly and bi-weekly applications of a selective insecticide Dipel® (Bacillus thuringiensis Berliner var. kurstaki) applied at 250 g/ha, and a broad-spectrum insecticide Dichlorvos (an organophosphate) applied at 1 ml/L against biological control (Control) on the pest population density on cabbage during October– December 2011 and March–May 2012. The use of both selective and broad-spectrum insecticides for experiments enables us to understand if efforts to optimise cabbage yield depend mainly on effective suppression of P. xylostella densities. Furthermore, investigations were carried out to determine the impact of these chemicals on parasitism rates of P. xylostella and species richness of its primary parasitoids. During the October–December 2011 growing season, the lowest infestation of P. xylostella occurred on cabbage plots that received weekly application of Dipel and the highest on untreated control plots. Cabbage weights were negatively related to infestation levels, implying that weekly application of Dipel yielded bigger cabbage heads. During March– May 2012, P. xylostella infestations were again higher on the control followed by weekly and bi-weekly treatments of Dichlorvos, then weekly and bi-weekly applications of Dipel. Despite the significant differences observed, infestation levels were much lower (< 1 P. xylostella per plant on average) in all treatments during this season. Consequently no significant differences in cabbage weights were observed among the treatments. The lower infestation levels were attributed to higher parasitism levels (≥50 %), especially during the early stages of crop development. A total of four parasitic Hymenoptera species were recorded from P. xylostella larvae and pupae during October–December 2011, while three species were recorded during March– May 2012. However, Cotesia vestalis (Haliday) (Braconidae) accounted for >80 % of total parasitism levels in all treatments. Parasitism levels were not significantly different among the treatments in both seasons. Parasitoid species richness was highest on the control. Although two parasitoid species were recorded in all Dipel and Dichlorvos treatments during October–December 2011, only one parasitoid species was recorded in the Dipel treatments during March–May 2012 compared to two species in Dichlorvos treatments. Although weekly applications of Dipel ensured good yield and crop quality during October–December, weekly applications of the chemical did not lead to better quality crop during March–May crop growing season. Thus, it is not necessary to apply insecticides during periods in which natural mortality of P. xylostella is high due to parasitoids. Since P. xylostella abundance was a determining factor of crop quality, these results imply that insect pest management should focus mainly on suppressing its numbers. Furthermore, there was no evidence that application of either insecticide type had a negative impact on parasitism rates of P. xylostella. The lower parasitoid species richness on Dipel treated plots was the consequence of its higher efficiency in suppressing the pest population which substantially reduced availability of potential hosts for parasitoids, hence only the efficient C. vestalis was recorded at low host densities / Agriculture and  Animal Health / M.Sc. (Agriculture)

A anemia causada por deficiência de ferro é a forma mais comum de todas as anemias e afeta grande parcela da população mundial, especialmente o grupo materno-infantil: lactentes, pré-escolares, escolares, gestantes e nutrizes. A carência acarreta atraso no desenvolvimento psicomotor e cognitivo de crianças menores de dois anos, além de diminuição da eficiência da função imune, e agravamento de doenças infecciosas. O presente estudo teve por objetivos avaliar a disponibilidade de ferro em alimentos fontes deste e de vitamina A, ovo (o), cenoura (c) e couve (cv), bem como verificar a interação do ferro com &#945; e ß-caroteno, e com outros interferentes. As misturas foram de ovo com cenoura e ovo com couve em diferentes proporções (1:1), (1:1,5), (1:2), (1:2,5) e (1:3) e também dos 3 alimentos sozinhos, totalizando 13 amostras. As amostras, após pré-preparo e cocção, foram submetidas às análises de composição centesimal, ferro, taninos, ácido fítico, ácido oxálico, &#945;- e &#946;- caroteno e ferro dialisável. Os dados foram submetidos à análise estatística empregando o teste de Tukey, regressão polinomial e correlação, utilizando o software SAS (1996). Os valores para umidade variaram de 83,93 a 95,74 g/100g, apresentando diferenças significativas entre as distintas amostras, assim como para proteínas (0,55 a 7,22g /100g) e extrato etéreo (0,21a 5,94 g/100g). Foi observado que em relação à umidade, extrato etéreo, proteínas, cinzas e &#946;-caroteno houve correlação significativa para o ferro dialisável, sendo que para umidade e &#946;-caroteno essa correlação foi positiva e para os demais componentes foi negativa. Os teores para taninos, fitatos e oxalatos variaram de 0,78 a 1,40 mEqcatequina/g, 0,17 a 0,42 mg/g, e 0,06 a 0,30% respectivamente. A amostra 2 (1o:1,5c) apresentou teores mais elevados de taninos (1,40 mEqcatequina/g), e as amostras 6 (1o:1cv) e 7 (1o:1,5cv) apresentaram teores mais elevados de oxalato e teores de ferro dialisável mais baixo, em relação às outras misturas. O teor de &#945;-caroteno para as amostras contendo cenoura variou de 2.435,27 a 4.609,83 µg/100g. Quanto ao &#946;-caroteno observou-se variações de 2.406,75 a 7.881,55 µg/100g, sendo evidenciado valores mais elevados para as amostras com cenoura. Numericamente, as misturas com maior proporção de cenoura e couve apresentaram os maiores resultados para o ferro dialisável, que variou entre 0,99 a 7,43%, sendo que a amostra 5 (1o:3c) apresentou o melhor resultado, seguida pelas amostras 1, 2, 3, 4, 8, 9 e 10. Pelos resultados obtidos pode-se concluir que as misturas com maior proporção de cenoura e couve aumentaram a disponibilidade do ferro, principalmente pelo maior conteúdo de ß-caroteno. Não houve interferência significativa dos antinutricionais sobre o ferro dialisável, embora os taninos e ácido oxálico atuaram como fatores limitantes quando observados os valores numéricos nas amostras com maiores concentrações de cenoura e couve. O ß-caroteno apresentou correlação positiva significativa com o ferro dialisável, exercendo influência na redução do efeito dos antinutricionais, especialmente dos fitatos, na disponibilidade do ferro, principalmente nas amostras com cenoura. Assim, pode ser recomendada a utilização de misturas de alimentos como ovo e cenoura, sendo que este último deve estar em maiores proporções em refeições destinadas a populações carentes em ferro. / The anemia caused by iron deficiency, is the form more common of all the anemias and it affects large portion of the world population, especially the maternal-infantile group: infants, child-school, children, pregnant woman and nutrizes, carting delay in the development psicomotor and cognitive of smaller children two years old, besides decrease of the efficiency of the immune function, and worsening of infectious diseases. This research aims to estimate the iron availability in food iron sources and vitamin A, egg (e), carrot (c) and cabbage (cb), as well as to verify the interaction of the iron with &#945;, ß-carotene and with other interferents, being mixed the foods in study, resulted 13 food mixtures in different proportions (1:1), (1:1.5), (1:2), (1:2.5) and (1:3) include three food alone. The food mixtures, after prepare and cooking, was submitted the analyses of centesimal composition, levels of iron, tannin, phytic acid, oxalic acid, &#945;, ßcarotene and in vitro iron dialysability. The statistical analysis was determinate by SAS System include polynomial regression and correlation. The values for moisture varied from 83.93 to 95.74 g/100g, showing significant differences among the different mixtures, as well as for proteins (0.55 to 7.22 g/100g) and fat (0.21 to 5.94 g/100g). There was significant correlation with regard to moisture, fat, protein, ash and ß-carotene to in vitro iron dialysability, being positive correlation to moisture and ß-carotene, and negative to other components. The levels of tannins, phytate and oxalates ranged 0.78 to 1.40 mEqcatequina/g, 0.17 to 0.42mg/g and 0.06 to 0.30%, respectively. The mixture 2 (1e:1.5c) showed high levels of tannins (1.40mEqcatequina/g), and the mixtures 6 (1e:1cb) and 7 (1e:1.5cb) high levels of oxalates, and lower levels of in vitro dialysability iron, in relation to the other mixtures. The values for &#945;- carotene to mixtures with carrot ranged 2,435.27 to 4,609.83 µg/100g. With regard to ß-carotene, ranged variations to 2,406.75 from 7,881.55 µg/100g, being observed higher levels for the mixtures with carrot. The numbers showed that the mixtures with larger carrot and cabbage proportion showed the bigger results for the in vitro dialysability iron, ranges to 0.99 from 7.43 %, and the sample 5 (1e:3cb) it presented the bigger value, proceeded by the mixtures 1, 2, 3, 4, 8, 9 and 10. It’s concluded that the mixtures with larger carrot and cabbage proportion increased the iron availability, especially for the largest content of ß-carotene. There was not significant interference of antinutritional in the in vitro iron dialysability, although tannins and oxalates were an inhibitor when observed the numeric values in the mixtures with larger carrot and cabbage concentrations. The ß-carotene showed significant positive correlation with in vitro iron dialysability, increasing influence in the reduction of the antinutritional factors effect, especially phytates, in the iron availability, mainly in the mixtures with carrot. Therefore, the use of food mixtures as egg and carrot can be recommended, and this last one should be in larger proportions in meals destined to lacking populations in iron.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-16T13:44:43Z No. of bitstreams: 1 Adriano Marcio Freire da Silva.pdf: 233973 bytes, checksum: 8365664074820b5955fb940c37b47616 (MD5) / Made available in DSpace on 2017-02-16T13:44:43Z (GMT). No. of bitstreams: 1 Adriano Marcio Freire da Silva.pdf: 233973 bytes, checksum: 8365664074820b5955fb940c37b47616 (MD5) Previous issue date: 2005-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Lettuce (Lactuca sativa L.) and Chinese cabbage (Brassica pekinnensis L.) may present yield reduction due to the occurrence of soft rot caused by Pectobacterium carotovorum subsp. carotovorum. Surveys of the intensity of soft rot in plantations of lettuce and Chinese cabbage were performed from January to May 2004 in mesoregions of the Zona da Mata and Agreste of the state of Pernambuco, Brazil. Disease prevalence of 45.2% was observed in lettuce and 100% in Chinese cabbage. The incidence of soft rot ranged from 0 to 22% in lettuce and 1 to 67% in Chinese cabbage. In lettuce higher intensity of soft rot was observed in areas: having more than 17 years of cultivation; planted with ‘Elba’, ‘Cacheada’ and ‘Tainá’; with clay soil type; irrigated by hosing and having poor drainage. Lower disease intensity was detected in areas: planted with ‘Verdinha’ and ‘Salad Bowl’; having coriander asprevious crop and when seedlings were produced in trays. In Chinese cabbage higher intensity of soft rot was found in areas having more than 10 years of cultivation, and in plantations with more than 50 days. The sole subspecies detected causing soft rot in all areas of lettuce and Chinese cabbage was Pectobacterium carotovorum subsp. carotovorum. To determine the ideal sample size for assessing incidence of soft rot in field, pilot-samples were conducted in eight lettuce planting areas and five Chinese cabbage planting areas, located in the main production municipalities in the state of Pernambuco. Based on our data and considering 20% of acceptable error, future surveys of the soft rot incidence should analyze 32 plots/ha and 20 plants/plot with 4.5m2 for lettuce and 21 plots/ha and 20 plants/plot with 10.5m2 for Chinese cabbage. For both crops there was significant correlation (P=0.05)between the intensity of disease aggregation and sample size but not between disease incidence levels and sample sizes / Os cultivos de alface (Lactuca sativa L.) e couve-chinesa (Brassica pekinnensis L.) podem ter a produção reduzida, devido à ocorrência da podridão-mole causada por Pectobacterium carotovorum subsp. carotovorum. No período de janeiro a maio de 2004, foram realizados levantamentos da intensidade da podridão-mole em plantios de alface e couve-chinesa, nas mesorregiões da Zona da Mata e Agreste do estado de Pernambuco. A prevalência da doença foi de 45,2% em alface e de 100% em couve-chinesa, enquanto a incidência variou entre 0 a 22% na primeira cultura e 1 a 67% na segunda. Em alface, maior intensidade da podridão-mole foi constatada em áreas: com mais de 17 anos de plantio; plantadas com as cultivares Elba, Cacheada e Tainá; com solo argiloso; irrigadas pelo sistema de rega e com drenagem deficiente. Por outro lado, menor intensidade da doença foi observada emáreas: plantadas com as cultivares Verdinha e Salad Bowl; cultivadas anteriormente com coentro e onde foram plantadas mudas produzidas em bandejas. Em couve-chinesa, observou-se que a intensidade da podridão-mole foi maior em áreas: com mais de 10 anos de cultivo e em plantios com mais de 50 dias. A única subespécie encontrada causando podridão-mole em todas as áreas de cultivo de alface e couve-chinesa foi Pectobacterium carotovorum subsp. carotovorum. Para a estimativa do tamanho ideal das amostras para avaliação da incidência da podridão-mole em campo, foram conduzidas amostragens-piloto em oito áreas de plantio de alface e cinco de couve-chinesa, situadas nos principais municípios produtores do estado de Pernambuco. Considerando os resultados obtidos e um erro aceitável de 20%, emfuturos levantamentos da incidência da podridão-mole, recomenda-se a amostragemde 32 parcelas/ha e 20 plantas por parcela de 4,5m2 para a alface e de 21 parcelas/ha e 20 plantas por parcela de 10,5m2 para a couve-chinesa. Para as duas culturas, houve correlação significativa (P=0,05) entre a intensidade de agregação da doença e o tamanho da amostra, mas não entre os níveis de incidência da doença e os tamanhos das amostras

Made available in DSpace on 2016-04-28T14:58:57Z (GMT). No. of bitstreams: 1 2007-Arison Jose Pereira.pdf: 1430968 bytes, checksum: d3480d26487e4c0b7569cb0b9d461014 (MD5) Previous issue date: 2007-03-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The objective of this work was to evaluate growth of Crotalaria species in different soil and climate conditions and to investigate the contribution of Crotalaria juncea, as a cover crop, on organic cultivation of cabbage and cauliflower, under no-tillage system. Five experiments were conducted. Three of them referred to the performance of Crotalaria species, evaluated in the spring/summer and fall/winter periods, on the experimental field at Embrapa Agrobiologia, in Seropedica, Rio de Janeiro State, and in the spring/summer period, on the experimental field at Pesagro-Rio, in Paty do Alferes, Rio de Janeiro State. Treatments consisted of the species Crotalaria juncea, C. mucronata, C. spectabilis, C. ochroleuca and C. breviflora arranged in a randomized blocks design. The aboveground biomass production was determined throughout the flowering period and the biological nitrogen fixation (BNF) was measured by the 15N natural abundance technique. Functional analysis of growth and soil cover rates were also determined in the first experiment. The fourth experiment evaluated green manuring with sunnhemp (C. juncea) on yield, productivity and nutrient accumulation of cabbage heads, on the experimental field at Pesagro-Rio, in Paty do Alferes, Rio de Janeiro State. A complete randomized block design was used and treatments were arranged in a 2x2x2 factorial split-plot: pre-cropped sunnhemp and fallow with spontaneous weeds, conventional tillage and no-tillage planting systems and 0 and 200 kg ha-1of N in a poultry manure. The fifth experiment was carried out on the experimental field at Pesagro-Rio, in Nova Friburgo, Rio de Janeiro State. The effect of green manures sunnhemp, millet, sunnhemp + millet and fallow with spontaneous vegetation, arranged in a complete randomized block design, was evaluated on weight and productivity of cauliflower cropped in no-tillage system. The contribution of sunnhemp mulch to nitrogen nutrition of cauliflower was assessed by isotopic dilution of 15N. Results from the first experiment showed that Crotalaria juncea presented the highest scores of growth rate and biomass production and reached 50% soil coverage at 15 days after seeding. Dry matter production, nitrogen accumulation and nitrogen coming from BNF reached superior rates in C. juncea, in the first and in the third experiments, and in C. ochroleuca in the second experiment. Trials number four and five showed why green manure can be considered a promising method to cultivate organic vegetables. No-tillage cabbage cropping under sunnhemp mulch discarded additional organic manure as head productivity reached 56 Mg ha-1. In the fifth experiment, 39% of cauliflower nitrogen content was originated from sunnhemp and productivity increased 42% in relation to spontaneous vegetation. / O objetivo geral deste trabalho foi caracterizar o desenvolvimento de esp?cies de Crotalaria L. em diferentes condi??es edafoclim?ticas e a contribui??o da aduba??o verde com C. juncea no cultivo org?nico de br?ssicas em sistema plantio direto. Foram conduzidos cinco experimentos: tr?s referentes a avalia??o das esp?cies de Crotalaria L., sendo dois no Campo Experimental da Embrapa Agrobiologia em Serop?dica-RJ (Baixada Fluminense). O primeiro foi instalado no per?odo de primavera-ver?o e o segundo no outono-inverno. O terceiro experimento foi conduzido no Campo Experimental de Avelar da PESAGRO-RIO, em Paty do Alferes-RJ (M?dio Vale do Para?ba Fluminense), no per?odo de primavera-ver?o. O delineamento experimental adotado nesses experimentos foi de blocos ao acaso e os tratamentos constaram das esp?cies Crotalaria juncea, C. mucronata, C. spectabilis C. ochroleuca, e C. breviflora. A produ??o de fitomassa a?rea foi determinada por ocasi?o do florescimento e a quantifica??o da FBN foi estimada utilizando-se a t?cnica de abund?ncia natural de 15N. No primeiro experimento, foram tamb?m realizadas an?lises funcionais de crescimento e determinadas ?s taxas de cobertura de solo. No quarto e no quinto experimentos, foram avaliadas as contribui??es da aduba??o verde com Crotalaria juncea no cultivo em sistema plantio direto de repolho e couve-flor. O trabalho com a cultura de repolho foi conduzido no Campo Experimental de Avelar da PESAGRO-RIO, sendo formado de oito tratamentos dispostos em blocos ao acaso, com arranjo fatorial em parcelas subdivididas (2 x 2 x 2). Os tratamentos foram: pr?-cultivo formado a partir de C. juncea e pousio com a vegeta??o espont?nea; preparo convencional do solo e plantio direto do repolho; e doses de aduba??o org?nica de cobertura (equivalente a 0 e 200 kg.ha-1 de N total contido na cama de avi?rio). As avalia??es constaram da produ??o e produtividade de cabe?as e acumula??o de nutrientes na parte a?rea do repolho. O quinto experimento foi conduzido na Esta??o Experimental de Nova Friburgo da PESAGRO-RIO regi?o serrana fluminense, com a cultura da couve-flor cultivado em sistema plantio direto, sendo o delineamento experimental de blocos ao acaso, com quatro tratamentos: pr?-cultivo com C. juncea; milheto; cons?rcio milheto + C. juncea; e pousio com vegeta??o espont?nea. As avalia??es consistiram do peso m?dio e produtividade de couve-flor e quantifica??o da contribui??o da palhada de C. juncea para a nutri??o nitrogenada desta hortali?a, empregando-se a t?cnica de dilui??o isot?pica de 15N. Observou-se a partir dos resultados do primeiro experimento que C. juncea apresentou maior taxa de crescimento e maior produ??o de fitomassa a?rea do que as demais esp?cies avaliadas. Aos 15 dias ap?s semeadura, C. juncea alcan?ou 50 % de cobertura do solo. Observou-se que a maior produ??o de fitomassa a?rea seca, acumula??o de nitrog?nio e quantidade de N proveniente da FBN foram detectados na C. juncea, tanto no primeiro quanto no terceiro experimentos, conduzidos na Baixada Fluminense, respectivamente nos per?odos de primavera-ver?o e outono-inverno. No segundo, conduzido no Vale do Para?ba, a maior produ??o de fitomassa a?rea seca, acumula??o de nitrog?nio e quantidade de N proveniente da FBN foram alcan?ados com C. ochroleuca. Pelos resultados apresentados nos experimentos quatro e cinco, detectou-se que a aduba??o verde ? uma pr?tica promissora para o cultivo de hortali?as org?nicas, porque, no quarto experimento, conduzido no Vale do Para?ba, o plantio direto sob palhada formada por C. juncea, dispensou a aduba??o org?nica suplementar, proporcionando produtividade de cabe?as do repolho de at? 56,0 Mg.ha-1. E no quinto experimento, conduzido na regi?o Serrana Fluminense, observou-se que 39% do N contido na couve-flor foi derivado da C. juncea e que o cultivo na palhada desta leguminosa resultou aumento de produtividade de at? 42% em rela??o a ?rea mantida sob pousio.