Nilton Garcia Marengoni

Produtividade e componentes de produção da soja adubada com diferentes doses de fósforo, potássio e zinco

O correto incremento da produtividade agricola deve estar aliado ao avanco tecnologico no conhecimento das exigencias nutricionais de cada cultura, proporcionando, dessa forma, o correto uso de insumos na propriedade agricola. Com o objetivo de estudar a resposta de plantas de soja ao zinco (Zn) em relacao a diferentes doses de fosforo (P) e potassio (K), foi realizado este experimento no municipio de Palotina-PR. O solo foi classificado como Argissolo Vermelho-Amarelo eutrofico. Os tratamentos foram arranjados em esquema fatorial 3x3, constituindo tres formas de adubacao com P2O5 e K2O: sem adubacao, uma vez e duas vezes a recomendacao de adubacao pela analise de solo e tres doses de Zn (0; 2 e 4 kg ha-1). Como fonte de nutrientes, foram utilizados fosfato bicalcico para P, cloreto de potassio para K e sulfato de zinco para Zn. As doses de Zn aplicadas nao influenciaram, significativamente, a produtividade, nao sendo justificada a sua suplementacao na forma de adubacao de base. Ja a adubacao com P2O5 e K2O provocou significativo aumento da produtividade e aumento do numero de legumes por planta, com aumento das doses desses nutrientes no solo.

Produtividade do milho em resposta a adubação com NPK e Zn em argissolo vermelho-amarelo eutrófico e latossolo vermelho eutroférrico

Objetivando-se avaliar os componentes de producao e a produtividade da cultura do milho em funcao da adubacao, com diferentes doses de Zn (Zinco), e NPK (nitrogenio, fosforo e potassio), realizou-se este trabalho nos municipios de Palotina - PR, em Argissolo Vermelho - Amarelo eutrofico e Marechal Cândido Rondon - PR, em Latossolo Vermelho eutroferrico. Os tratamentos foram arranjados em esquema fatorial 3x3 constituindo tres doses de adubacao NPK: sem adubacao; uma vez (30-100-50 kg ha-1), e duas vezes a recomendacao de adubacao (60-200-100 kg ha-1), com base na analise do solo. Outro fator em estudo foi o Zn, em diferentes doses: 0,0; 5,0 e 10,0 mg dm-3. As parcelas corresponderam a 3,6 m de largura por 6 m de comprimento. Foram semeadas 4 linhas espacadas com 0,9 m, utilizando-se como parcela util as 2 linhas centrais, descartando-se 1,5 m de bordadura. A populacao de plantas foi de 6,5 sementes, por metro linear. Com relacao a adubacao de NPK (nitrogenio, fosforo e potassio), obteve-se aumento significativo para os componentes: numero de graos, massa de 1000 graos e a produtividade, sendo a dose 60-200-100 kg ha-1 a que proporcionou os melhores resultados no Latossolo Vermelho eutroferrico e no Argissolo Vermelho-Amarelo eutrofico, proporcionou aumento significativo na massa de 1000 graos e na produtividade. Em relacao a adubacao com o Zn, nao obteve-se aumento significativo, nos dois solos, entre os tratamentos para os componentes avaliados e a produtividade. Com este trabalho, pode-se concluir que a adubacao com NPK aumentou a produtividade da cultura nos dois solos e na adubacao com Zn nao se obteve diferencas de produtividade, para a cultura do milho.

Desempenho e proporção sexual de tilápia vermelha sob à inclusão de probiótico em água mesohalina

A tilapia vermelha e uma especie que se adapta bem as altas salinidades sendo uma otima candidata ao cultivo em aguas mesohalinas. Os probioticos sao suplementos alimentares que podem melhorar o desempenho produtivo na piscicultura. Objetivou-se avaliar o desempenho produtivo e a proporcao sexual de alevinos de tilapia vermelha (Oreochromis sp., linhagem Saint Peter) em aguas mesohalinas a 0,5 e 1,0% sob inclusao de niveis crescentes de probiotico (0, 5, 10 e 15 g de probiotico/kg de racao comercial). Foram usadas como unidades experimentais o sistema de recirculacao de agua - RAS (experimento I) e o tanque-rede - TER (experimento II) utilizando 0,5% e 1,0% de aguas mesohalinas respectivamente. Utilizou-se o delineamento completamente casualizado com quatro tratamentos e tres repeticoes. O desempenho produtivo e ajuste no fornecimento de racao foram monitorados por biometrias quinzenais com duracao de 42 e 70 dias para RAS e TER, respectivamente. O peso, ganho de peso, biomassa, ganho de biomassa, conversao alimentar, ganho de peso medio diario, crescimento especifico, fator de condicao, sobrevivencia nao foram influenciados pela inclusao de probiotico (p>0,05) nas duas unidades experimentais. A proporcao sexual dos alevinos tanto na salinidade 0,5% quanto 1,0% nao foi influenciada (p>0,05) pelos niveis de inclusao de probiotico. Ao final dos experimentos, tanto o peso corporal, quanto o comprimento total dos animais apresentaram comportamento geometrico. Os niveis de probiotico utilizados na racao comercial para a alevinagem de tilapia vermelha cultivados em agua mesohalina, tanto em aquario como em tanques-rede nao justificam sua aplicabilidade e eficiencia como promotor de crescimento nem como controlador de populacoes monossexo de machos.

Probióticos em dietas para tilápia do Nilo durante a reversão sexual

The objective was to evaluate the productive performance, phenotypic sexing, and intestinal microbiology of Nile tilapia, GIFT strain, fed with diets formulated with Bacillus cereus var. Toyoi and Bacillus subtilis C-3102, during sex reversal. Fish (24.7±0.50mg) were randomly distributed in 24 aquaria in a completely randomized design compound for three treatments (two probiotics and absent) and eight replications. The use of B. cereus and improved the final weight, weight gain, average daily weight gain and specific growth rate fed in relation to B. subtilis. There was no association between the proportion of males and females and inclusion of the probiotics. The counts of total bacteria and total coliforms were not influenced by the addition of probiotics. Bacillus subtilis did not improve the productive performance in Nile tilapia. Bacillus subtilis did not improve the productive performance of Nile tilapia. Among the two studied probiotics is recommended probiotic containing Bacillus cereus C-3102 not adversely affect the sex reversal effectiveness and performance zootechnical.

Morphological characteristics of ovarian development of two Nile tilapia (Oreochromis niloticus) strains in mixed-culture systems

This study was carried out to morphologically characterize and classify the stages of gonad development in different Nile tilapia strains (Oreochromis niloticus). Eighty-four and ninety-two ovaries from Bouake and Chitralada strains, respectively, were evaluated at different ovarian developmental phases: initial (104 days of culture), intermediate (152 days of culture), and the final (279 days of culture). The ovaries were microscopically evaluated and submitted to histological processing and hematoxylin-eosin staining to determine their characteristics and be classified. No morphological differences in ovaries between strains were observed during the initial phase (stage A - immature). During the intermediate growing phase, higher gonad development was observed for Chitralada strain (stage B - maturation) in comparison with Bouake strain (stage A - immature). During the final growing phase, no differences between strains were observed for morphological characteristics (stage C - mature). Despite the similarities in reproductive behavior of the Bouake and Chitralada females at the end of the final growing phase (gain weight phase), differences for macroscopic and microscopic aspects and oocytes during the initial and intermediate growing phases of the strains were observed.

Monogenoidea (Dactylogyridae) em tilápias-do-nilo cultivadas sob diferentes densidades de estocagem em tanques-rede

The prevalence and infection intensity of Monogenoidea in Nile tilapia (Oreochromis niloticus) cultivated under different stocking densities in 4m3 cages were evaluated. The experiment was designed in sample random sampling with four treatments - densities (D) of D1=250, D2=300, D3=350, and D4=400 fish/m3- and three repetitions, using 360 fish captured and analyzed during the period from February to June 2003. Physiochemical parameters of the water were monthly monitored. Prevalences of 52.8; 62.5; 69.4; 83.3; and 58.3% and parasitic mean intensities of 112.8; 65.7; 274.0; 97.8; and 100.2 Dactylogyrus sp. (Monogenoidea: Dactylogyridae) were observed. No relationship between the prevalence and infection intensity with the cultivation density was found. However, quadratic effect was verified (P<0.05) related to the parasitic intensity in function of the month. High mean intensity of infection (274) and high prevalence (83.3%) were verified in the months in that the temperature and the transparency of the water oscillated below the recommended limits for the thermal comfort and well-being of tilapia.

Evaluation of the performance of two strains of Nile tilapia (Oreochromis Niloticus) in mixed raising systems

The aim of this study was to evaluate the productive performance of two strains of Nile tilapia (Oreochromis niloticus) in mixed raising systems. A total of 3600 fish-larvae species was used, 1800 belonging to Bouake lineage, and 1800 to Chitralada. The experiment was carried out in three phases; Phase I in an incubator in 18 boxes, in which two treatments (Bouake and Chitralada) were tested by using nine repetitions; Phases II and III were performed in 18 cement tanks with the same treatments. In phase I, regarding the final weight and gain of weight, Chitralada strain showed the highest final weight values. In phase II, Chitralada showed the highest final weight value when compared with Bouake, and, considering the gain of weight, Bouake obtained the best result. In phase III, Chitralada showed better final weight results (104 days of raising), final weight, final length and gain of length/cm (152 days of raising); but, after 279 days of the cultivation, Bouake showed a higher weight and length gain. These findings showed that Chitralada strain presented the best performance.

Bioacumulação de metais pesados e nutrientes no mexilhão dourado do reservatório da Usina Hidrelétrica de Itaipu Binacional

This study aims to evaluate the bioaccumulation of macronutrients and heavy metals in the golden mussel according to its collection site and seasonality in the aquaculture area of the reservoir from April/2009 to March/2010. There is no difference (p > 0.05) in the concentration of metals with respect to the point of collection. The concentrations of Cu, Fe, Mn, Zn, Cd and Pb were higher (p < 0.05) in spring and summer than in fall and winter. Values of the heavy-metal pollution index (MPI) for collection point and seasonality indicate environmental contamination in the aquaculture area.

Óleo essencial de alho aumenta as taxas de fertilização de ovos e de eclosão de larvas de Rhamdia quelen em sistema de incubação artificial

The objective of this study was to evaluate the effects of garlic (Allium sativum) essential oil on the rates of eggs fertilization and hatching and on the normal development of larvae of artificially incubated silver catfish (Rhamdia quelen). The experiment was carried out using a completely randomized experimental design with four treatments and five replicates. The treatments consisted of introducing garlic essential oil into the incubators, which used a closed system of water recirculation, at concentrations of 0, 1, 3, and 5mg L-1. Rates of eggs fertilization and larval hatching were determined at 10 and 24h after the beginning of eggs hydration. Morphology of larvae was assessed with the aid of a stereo microscope to determine the rate of normal development. The concentration of 5mg L-1 promoted better rates of eggs fertilization and larval hatching. Concentrations of garlic essential oil had a linear effect on eggs fertilization rates and larval hatching. Garlic oil did not influence the morphology of the larvae (P>0.05). It is recommended to use 5mg L-1 of garlic essential oil to promote better rates of eggs fertilization and larval hatching of artificially incubated silver catfish.

Reproduction and sex ratio in red Saint Peter tilapia, under different salinities

The effect of different salinities (0, 5, 10, 15, 20, 25, 30, 35 and 40 ppt) was analysed on the reproductive performance of red tilapia, Oreochromissp., var. Saint Peter. Couples were selected for breeding, acclimated, weighed, measured and distributed in aquariums of 170 L, where they remained for a period of 28 days. Once mating had occurred, the eggs were collected, counted to determine absolute and relative fecundity, and transferred to artificial incubators. After hatching, the larvae were counted to determine the hatch rate, and stored in circular, 1000 L tanks, where they remained until reaching a suitable size for the gonad smear method to be carried out. Salinity was monitored by refractometer and kept constant. The parameters, temperature, dissolved oxygen and pH were measured daily. Absolute and relative fecundity varied respectively between 772.25 ± 394.39 and 1268.33 ± 36.50 eggs spawning-1, and 5.49 ± 3.31 and 7.44 ± 3.76 eggs g-1. Hatch rates of 56.34 ± 22.86%, 25.08 ± 2.07%, 42.53 ± 3.93%, 33.76 ± 6.65% and 11.56 ± 5.23% were seen respectively for the salinities 0, 5, 10, 15 and 20 ppt. Percentages of males of 32.00%; 54.69%; 64.71%; 46.00% and 56.00%, were found respectively for the salinities 00, 5, 10, 15 and 20 ppt. The Saint Peter variety was able to spawn, followed by hatching, at salinities of 0, 5, 10, 15 and 20 ppt. At 25 ppt, only spawning took place. No spawning was seen at 30, 35 and 40 ppt.