The plant species used as ground cover preceding the commercial crops cultivation in the Cerrado must be adapted to the climate and soil of the region, so they have high biomass productivity and offset the decomposition high rates that occurs in these regions. This study aimed to evaluate the biomass yield and the decomposition rate of residues of different cover crops preceding soybean cultivation in Uberaba-MG, Brazil. The experiment was conducted in 2011/12 period in a randomized complete block design in plots with 2 m2 with treatments comprise the following covers: jack bean, millet, sunn hemp and brachiaria. It was evaluated: the dry biomass yield, the decomposition rate through of the bags decomposition, productivity, number of beans per plant, and mass of 100 soybean grains. The millet was the plant cover that showed the highest yield of dry biomass (5.22 Mg ha-1) during the study period. The decomposition of crop residues occurred at accelerated rate until to complete 120 days and after that the rate slowly up until 240 days. Sunn hemp and jack bean were the cover crops with the decomposition highest rates and the smaller half-lives were observed; soybean yield was not affected by the soil covers.

This paper describes the composition of fatty acids in oil extracted from seeds of carnaúba ( Copernicia prunifera (Miller) H. E. Moore), an important palm species native to Northeastern Brazil. After extracting the crude oil, the physico - chemical characteristics (density, refraction index, pH, acidity and saponi- fication index) were registered and the chemical composition of the fatty acids was determined by gas chroma- tography (GC - FID). The predominance of saturated fatty acids does not make carnaúba seed oil a promising alternative for the food industry, and the small yield obtained (approx. 5%) may constitute a limiting factor for commercial exploitation, but carnauba seed oil could potentially be used in the production of biofuels, cosmet- ics and detergents.

Drip irrigation is one of the most efficient method s forapplyingwaterto a crop, capable of deliv- ering water at a rate close to the demand. Many eff orts have been required to estimate the amount of w ater needed by plants. Therefore studying soil water ext raction by plants linked to mathematical modeling f or be- havior prediction, and linked to computational reso urces to allow complex mathematical procedures to b e real- ized in a short space of time, becomes a powerful a nd necessary alternative for the understanding and quantifi- cation of the involved processes. Simulations were performed through a computational model, with the purpose of estimating the crop coefficient (K c ) of watermelon in the region of Mossoró-RN, using a three-dimensional macroscopic root water uptake model, which solves t he sink term of the Richards equation. The simulati ons results were compared with an experiment that estim ated the K c using lysimeter. The results of Kc estimated by the model showed a good agreement with lysimeter re sults in all chosen statistical indexes, indicating that the model can serve as a tool for predicting transpirat ion and evaporation of soil water under certain con ditions, and as a tool to aid the irrigation management.

In agricultural areas of Cerrado, where there is no possibility of making two cultivation to the year, areas before cultivated with soybeans or corn, remain in fallow until the next crop year, where weed inci- dence is high. In this research was aimed assess the potential for weed suppression by cover crops, when sown in the off season of annual crops. The experimental design was a randomized block with eight treatments (Urochloa ruziziensis, Pennisetum glaucum, Crotalaria juncea, Crotalaria spectabilis, Styzolobium aterrimum, Canavalia ensiformes, Cajanus cajanand Stylosanthes macrocephala + Stylosanthes capitata) in four replica- tions. The evaluations were performed at 45, 90, 135 and 180 days after the sowing (DAS), with determination of dry mass, plant density and vegetal cover over the soil afforded by cover crops and weeds. The population dynamics was evaluated by means of phytosociological parameters. It is conclude that the weed community presents variations during the development cycle of the cover crop and the greater biomass production, soil cover vegetal and weed suppression was obtained with the U. ruziziensis.

The biocontrol of soilborne plant pathogens represents a promising approach from the environ- mental and practical points of view. Fluorescent pseudomonad rhizobacteria are well known by their antagonis- tic capacity towards several plant pathogens due to a diversity of antimicrobial metabolites they produce. This study was conceived to select and characterize rhizobacteria having antagonistic potential towards the patho- genic fungi Rhizoctonia solani and Sclerotium rolfsii. A total of 94 bacterial strains isolated from the rhizospheres of four vegetable species under organic cultivation were evaluated. Twenty-two strains which predominate in lettuce and rudbeckia rhizospheres showed identical biochemical profiles to Pseudomonas fluo- rescens, while in kale and parsley rhizospheres identical profiles to Pseudomonas putida (subgroups A and B) strains prevailed. Two types of antagonism were verified in vitro and defined as competition and inhibition of mycelial growth. Sixty percent of the evaluated strains showed antagonistic potential and, among those, 24 strains expressed antagonism to both target fungi, with P. fluorescens being the most representative bacterial species. This work clearly identified a number of strains with potential for use as plant growth-promoting and biocontrol of the two soilborne fungal pathogens in vegetable crops production systems.

The objective of this study was to propose monthly average values of Class “A” pan (Kp) for the Pajeu Middle region, as well as analyze the theirs effects in the estimate of agricultural crop evapotranspira- tion (ETc). Evaporation values of class "A" pan and daily weather data from a series of 1999 to 2011 were used. From the daily values of odd-numbered years were obtained monthly values of reference Kp (Kpref). That series was used in the implementation of six methods of estimation of the Kp. The values found have been sub- jected to an analysis of variance and t-test (p > 0.05). The performance of the Kp values was done by estima- tion of the accumulated ETc values of the six agricultural crops. It was verified that the Kpref provided the best statistical indexes and minor errors in the estimate of ETc. The methods of Pereira et al. and the FAO case A should the best estimates among those evaluated. On the other hand, the Snyder and FAO case B methods were those of the worst performances. The performance of the estimation of the ETc in the Middle Pajeu, using the evaporation values of Class "A" pan, is conditioned by the time of year and crop to be explored.

In order to study the effect of nitrogen sources upon the yields and nutrition of corn for silage and on the chemical attributes of a Cambisol, at Northern of Minas Gerais, Brazil, under calcareous water. The cultivar used was Decalb 390®, with a spacing of 0,8 m x 0,2 m. The base fertilization consisted in 330 kg ha-1 of formulation 4-30-10 and 50 kg ha-1 of FTE-BR12. Two equal dosages of 40 kg ha-1 of K2O, in the KCl form, were applied 45 and 60 days after corn sowing (DAS), phenologic phases V7 and V10 . The experiment it was realized in a randomized blocks design with six repetitions, been the treatments constituted by: ammonium sulfate (topdressing manuring), urea (topdressing manuring), Crotalaria juncea (before de maize crop). The Nfertilizers were applied parceled into three equal dosages of 40 kg ha-1, 30 DAS, with 15 days between fertilizations. The corn yields increased above control treatment average in 33, 27 and 14 t ha-1 with ammonium sulfate and urea topdressing and with C. juncea pre cropped, respectively. The ammonium sulfate use allows better recovery rate of the N applied by the extractor and higher uptake of Fe, Mn, Zn and S by the corn plants.

This study aimed to quantify the agro - industrial income and evaluating the quality of cassava minimally processed in minitolete and rubiene shapes. The assays were performed at the Academic Unit of Serra Talhada/ Federal Rural University of Pernambuco. Roots of sweet cassava cv. Mossoró were harvested at 14 months of age, minimally processed in minitolete and rubiene shapes and stored at 5 ± 2 °C and 90 ± 5 % of relative humidity for 11 days. Agroindustrial income, accumulated fresh weight, pH, soluble solids, soluble sugars and cooking time were evaluated. The experimental design was completely randomized in 2x6 factorial design, referring to shapes (minitolete and rubiene) and refrigerated storage times (0, 3, 5, 7, 9 and 11 days), respectively, with 3 replications. The agroindustrial income for each shape was calculated only at the end of minimal processing. The cooking time was measured at 0 and 11 days in 2x2 factorial design. The formats 'minitolete' and 'rubiene' minimally processed sweet cassava showed agroindustrial income above 60%. There- fore, it is suggested the minimum processing of sweet cassava in those shapes. Furthermore, the quality of the shapes was kept preserved throughout the 11 days of refrigerated storage. The 'rubiene' favored higher mean values of soluble sugars giving this format greater sweetness.

The cowpea considered one of the main dietary sources of tropical and subtropical regions. To population of the regions North and Northeast of Brazil represents an important socioeconomic activity. The objective of this study was to evaluate growth characteristics of cowpea under the residual effect of phosphorus fertilization. Research conducted on the screened greenhouse of the Department of Soil Science and Agricul- tural Engineering, Center of Agricultural Sciences, Federal University of Paraiba, Areia-PB. The substrates used were materials Oxisol textures of sandy clay and sandy clay franc that we fertilized with levels of 0, 40, 80, 120, and 160 kg ha-1 of P2O5. After fertilization, the cultures we performed with sunflower, corn and beans, respectively. Were analyzed the stem diameter, main branch length, leaf area, shoot dry weight and water con- sumption. The effect of residual phosphorus was significant for leaf area, dry weight of shoots and water con- sumption. The effect of soil was significant for all variables evaluated, except for the consumption of water. Phosphorus fertilization in sunflower, followed by maize cultivation has a positive effect on growth and water use by cowpea, third culture. The Oxisol of sandy clay loam texture led to the highest in diameter at ground level, main branch length and leaf area of cowpea.

Allelopathy can be defined as any effect , direct or indirect, beneficial or harmful, a plant on the other, through the release of chemical compounds into the environment. Thus, this study aimed at evaluat- ing, in the laboratory, allelopathic effects of aqueous extracts from cover crops as canola (Brassica napus L. var), crambe (Crambe abyssinica Hochst), sunn hemp (Crotalaria juncea), linseed (Linum usitatissimum L.) and forage turnip (Raphanus sativus L.) at 0, 12.5, 25, 50 and 100% concentrations. The plants used in aqueous extracts were collected during their flowering period of each studied species. Germination tests were performed on seeds gerbox, fresh and dry seedlings biomass, root and shoots seedlings length. The experimental design was completely randomized (CRD) in factorial (5x5) with four replicates per treatment. According to these results, it can be concluded that the tested extracts showed allelopathic effect on seedlings of lettuce, cucumber and soybean on almost all parameters, but for soybean germination and dry mass percentage, this effect was not significant. The sunn hemp extract, despite concentration, contributed the most to increased germination and seedling growth. However, linseed extract showed opposite effect for these parameters in 100% concentrations.