Aplicação de nitrogênio no solo e pulverização foliar com ácido giberélico e uréia em Setaria anceps Stapf cv. Kazungula

O objetivo do experimento foi verificar o efeito do nitrogénio no solo, parcelado de diferentes formas e aplicado durante o período de "verão", combinado com pulverização foliar de ureia e/ou ácido giberélico, sobre a produção e qualidade de Setaria anceps Stapf cv. Kazungula. O nitrogênio (60 kg/ha/ano) foi aplicado segundo quatro formas de parcelamento: Testemunha (sem nitrogênio), N20M40 (20 kg/ha de N em novembro + 40 kg/ha de N em março), N30M30 (30 kg/ha de N em novembro + 30 kg/ha de N em março), F20M40 (20 kg/ha de N em fevereiro + 40 kg/ha de N em março). No início do período de "inverno" foram aplicados os quatro tipos de pulverizações foliares: Testemunha (sem ácido giberélico ou uréia), uréia a 2%, ácido giberélico a 50 ppm e uréia a 2% + ácido giberélico a 50 ppm. Os resultados revelaram que o parcelamento do nitrogénio no solo não influiu no aumento da produção de matéria seca do capim setária no período de "verão", apesar de proporcionar um incremento da mesma no corte de "inverno". Observou-se, ainda, uma boa distribuição da produção de matéria seca entre "verão" e "inverno", apresentando essa última estação 34,52% da produção total anual, em média. Os diferentes tipos de pulverização não influíram significativamente sobre a produção de matéria seca e a composição química bromatológica da forrageira no período de "inverno".

Produtividade e qualidade de frutos do mamoeiro em função de tipos e doses de biofertilizantes

Biofertilizers are organic products usually obtained from an anaerobic process, evaluated mainly as phytoprotectors for agriculture, although they can improve fruit production. By this way, a field experiment was carried out in Remigio County, Paraiba State, Brazil, to evaluate the effects of two bovine biofertilizers on yield, medium mass and quality of papaya fruits (Carica papaya L.), 'Baixinho de Santa Amalia cultivar. Treatments were distributed in a randomized complete blocks design with three replications and 15 plants in each parcel, in a 2 x 5 factorial arrangement, with two biofertilizers: simple (water and fresh bovine manure) and supermagro (water, fresh bovine manure, macro and micronutrients and a protein mix), applied in soil under liquid form at five volumes, as follows: 0.0; 0.5; 1.0; 1.5; e 2.0 L cave(-1). There was no statistical difference between biofertilizers for fruit mass, yield and external and internal fruit quality variables, while between volumes differences were registered for both biofertilizers. The results, except for fruit firmness, registered positive effects of the biofertilizers on 'Baixinho de Santa Amalia' papaya cultivar in relation to yield and physical and chemical fruit quality.

Male gonadal denervation by guanethidine at pre-puberty: Different doses, different results. The intervention of the pineal deafferentation

Since gonadal denervation and pineal deafferentation by cervical superior ganglionectomy affect sexual development, this study was performed to evaluate testicular steroidogenesis, spermatogenesis and the cervical superior ganglion (CSG) histology in rats treated with guanethidine (GD). The treatment was performed by GD s.c. injections for 3 weeks, from the 21st day of age to the 41st day of age (pre-puberty), when the animals were sacrificed. Different doses were used: group A=10 mg/kg/day, group B=50 mg/kg/day and saline (control group). Testicular denervation was confirmed by HPLC for catecholamines in testicular tissue. Testicular concentrations (TC) of progesterone (P4) and testosterone (T) were measured by RIA. Significantly higher TC of P4 and lower TC of T were observed only in group A in comparison with group B and the control group. No alteration of sperm production was observed in either treated group. Histological analysis of CSG showed only few neuronal alterations in group A rats, while in group B the nervous cells were practically destroyed. This suggests that 10 mg/kg/day GD treatment probably produces a specific blockade of 17 alpha-hydroxylase/17,20 desmolase at pre-puberty leading to a decrease of the androgen production. However, in the 50 mg/kg/day group no differences were observed concerning the steroid profiles, this result being attributed to the extensive damage to the CSG observed only in group B. The CSG destruction causes deafferentation of the pineal gland producing abolishment of the inhibition of the 17 alpha-hydroxylase/17,20 desmolase promoted by melatonin or by an out of phase production of androgen.

Gas exchange in lisianthus plants (Eustoma grandiflorum) submitted to different doses of nitrogen

The effect of different doses of nitrogen (N) on gas exchange, relative chlorophyll (Chl) amount, and the content of N in the aerial biomass of lisianthus was evaluated. The treatments consisted of six different concentrations of N (50, 100, 150, 200, 250, and 300 g m(-3) noted as N-50, N-100, N-150, N-200, N-250, and N-300, respectively), applied through the fertirrigation technique. N-250 and N-300 induced increase in the contents of foliar Chl and N in the aerial biomass, that in turn contributed to an increase of photosynthetic activity in lisianthus.

Alterações na produtividade e composição nutricional de uma pastagem após segundo ano de aplicação de diferentes doses de cama de frango

The objective was to evaluate the potential use of poultry litter, compared to mineral fertilization, productivity, features bromatologic and absorption of nutrients from a pasture of Brachiaria decumbens. The experimental area was installed in oxisoil in Uberlandia-MG. The design was randomized blocks with four replicates and the treatments used: control (without application of organic or mineral source), mineral fertilizer (60, 75 and 100 kg ha(-1), P K, respectively); organic fertilization with poultry litter at rates of 3,125, 6,250, 9,375 and 12,500 kg ha(-1). There were two cuts of the aerial part of Brachiaria decumbens, both at 60 days after treatment. We evaluated the yield of DM and the levels of CP, NDF, ADF, lignin, macro and micronutrients in shoots of grass. The results showed that application of poultry litter increased the productivity of DM and the levels of CP, N, P, K and Zn in Brachiaria decumbens. The poultry litter can be used as supplementary source of nutrients, the mineral fertilizer. The use of poultry litter not increased over the levels of S, Ca and Mg in Brachiaria decumbens.

Manejo de irrigação e nitrogênio no feijoeiro comum cultivado em sistema plantio direto

With technological innovations, such as irrigation, the bean has been grown by producers who have the most varied levels of technology that, in suitable times, allows the planting great success in grain yield. The aim of this study was to evaluate the response of the dry bean to different managements of irrigation and nitrogen fertilization with no-tillage system, in Aquidauana - MS, Brazil. The experiment was conducted at the Universidade Estadual de Mato Grosso do Sul (UEMS), with the soil of the area classified as Alfisol, using the bean crop "Perola" sown on June 30, 2007. The experimental design was a randomized block split-plot consisting of three blocks and two replications within each block. The plots were composed of three management of irrigation, by the Class A pan method, using Hargreaves-Samani equation, and management by tensiometry (-40 kPa), with water replacement of 16.5 mm for all irrigation plots. The subplots consisted on four rates of nitrogen fertilization (0; 50; 100 and 150 kg ha(-1)), in which the nitrogen source was urea. It was concluded that the irrigation management through the Class A pan and Hargreaves-Samani equation conduced to higher grain yields of bean, 3031.11 and 3005.02 kg ha(-1) respectively.

Doses de potássio em cobertura na primeira soca da cultura da cana-de-açúcar cultivada no norte matogrossense

The sugar cane crop has been cultivated in all regions of the Brazil, occupying different soil types. The north region of Mato Grosso has favorable climate conditions for the culture, however, has been achieved low productivity due to the not application of fertilizer and inefficient doses. Being the potassium the mineral element absorbed in large amount by culture. Aimed to with this work to evaluate the effect of growing doses of the nutrient applied in coverage in the second cycle of the variety of sugar cane IAC86-2480. The experimental design was randomized blocks, with four replications. The Potassium doses were: 0; 60; 120; 180 e 240 kg ha(-1) of K(2)O. Was evaluated the degrees Brix, diameter, weigth, height and productivity of stalk. No was significant effects for the variable degrees Brix in response to potassium doses, since to others had response quadratic. The dose of maximum agronomic efficiency was of 150 kg ha(-1) de K(2)O obtaining productivity of 85 t ha(-1) of stalk, representing 25% increase in productivity.

High doses of dexamethasone induce increased beta-cell proliferation in pancreatic rat islets

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)