The objective of this study was to estimate the genetic potential of two maize populations, in order to verify their genetic potential under two production systems (with and without nitrogen stress). So, 49 half-sib families (FMI) of the population UFVM 100 and 49 FMI of the population UFVM 200 were randomly taken. The 7 x 7 lattice design was used, with two replicates. The high nitrogen level was established with planting fertilization more two side-dressing fertilizations, so totaling 120 kg/ha N (40 kg/ha N in planting fertilization; 40 kg/ha N at the 15 days after emergency - DAE; 40 kg/ha N at 30 DAE). The low nitrogen level was only 20 kg/ha N in planting fertilization. The experimental plot consisted of one row with 5m length and 0.90m spacing between rows and 0.20m among plants inside the rows. All experiments were subjected to water deficit (irrigation interruption) at flowering stage, during 7-day period, until soil water potential was between -0.09 to -0.1 MPa. The grain yield was evaluated in each plot. The variance analysis relative to those 49 FMI of each population in each production system was accomplished according to recommendation by Cochran and Cox (1957), whereas the estimates of the genetic parameters were performed according to method 1 presented by Silva et al. (1999), when considering the lattice experiments. After the individual analyses, those 15% more productive FMI were selected in each production system to estimate the expected selection gain when recombining them. It was found that only the population UFVM 100 shows genetic variability to be explored by selection based on half-sib families, for grain production under low N availability conditions; the estimates of the genetic parameters associated to grain yield were similar as for high and low nitrogen; the consistence of the agreement level between the families´ performances under low and high availability of nitrogen was low, therefore pointing out the need for conducting a specific improvement program when the objective is to obtain material adapted to nitrogen stress conditions.

Thirty-six females (of 1st, 2nd, 3rd, and ¿ 4th partum order) were used, and evaluated at four stages of lactation (equalization, 7th and 14th day of lactation, and at weaning) to verify the effects that partum order and lactation stage had on the performance of hybrid swine sows maintained in a hot environment (room temperature at 28.5ºC; black globe temperature at 29.3ºC; relative air humidity at 75.7% and ITGU calculated at 78.9). Interaction among the factors was observed for food consumption, and the primiparas consumed less. The sows presented differences (P<0,05) in performance (corporal weight, bacon thickness, visual corporal score, corporal composition and tissue) according to partum order, without effect on the weaning-estrus interval or the duration of the estrus. The lactation stage had a negative influence on weight and estimated corporal protein. This study concluded that hybrid swine sows maintained satisfactory performance, and that primiparous sows were more sensitive to hot environments.

The slag represent an alternative recommended to replace the traditional source of corrective or fertilizers. This study evaluated different base saturation levels, comparing basic slag to dolomitic limestone as soil acidity corrective agents and in the availability of calcium, magnesium and phosphorus. Thus, one experiment involving soil incubation was conducted in laboratory, during 60 days. The treatments consisted of two corrective agents: dolomitic limestone and basic slag, evaluated by the base saturation method, with eight correction levels (V%) (56, 58, 60, 62, 65, 67, 69 e 71 %) and two replicates. After the incubation period the soil samples was analyzed chemically. The application of the corrective agents promoted efficient neutralization of acidity in soil, especially when basic slag was used. The Ca + Mg level increased depending on the increasing amounts of correctives, reducing the K (Ca2+ + Mg2+)-0,5 ratio. The neutralization of acidity in soil reaction was fast when the slag was used. The soil available P did not increase with increasing levels of soil acidity correctives.

The weed control procedures are known to affect the soil physical attributes and the nutrient amount taken up by weed roots. This work hypothesis is that weed control methods might also affect soil chemical attributes. Four experiments were carried out, three with maize (E-1, E-2 and E-3) and one with cotton (E-4), in randomized complete blocks design arranged in split-plots, with five replications. In E-1 experiment, the plots consisted of two weed control treatments: no-weed control and weed shovel-digging at 20 and 40 days after sowing; and the subplots consisted of six maize cultivars. In the three other experiments, the plots consisted of plant cultivars: four maize cultivars (E-2 and E-3) and four cotton cultivars (E-4). And, the subplots consisted of three weed control treatments: (1) no-weed control; (2) weed shovel-digging at 20 and 40 days after sowing; and (3) intercropping with cowpea (E-2) or Gliricidia sepium (Jacq.) Walp. (E-3 and E-4). In all experiments, after harvest, eight soil samples were collected from each subplot (0-20 cm depth) and composed in one sample. Soil chemical analysis results indicated that the weed control by shovel-digging or intercropping may increase or decrease some soil element concentrations and the alterations depend on the element and experiment considered. In E-2, the weed shovel-dug plots showed intermediate soil pH, lower S (sum of bases) values and higher soil P concentrations than the other plots. In E-4, soil K and Na concentrations in plots without weed control did not differ from plots with intercropping, and in both, K and Na values were higher than in weed shovel-dug plots. Maize and cotton cultivars did not affect soil chemical characteristics.

The culture of the popcorn comes as a promising culture for region of the Brazilian northeast, however they are still scarce studies to make possible the expansion of this culture, especially as the fertilization. This experiment was accomplished in the department of Environmental Sciences of the Rural Federal University of the Semi-arid (UFERSA), Mossoró, RN, with the objective of evaluating the effect in different ammonium:nitrate ratios in the initial development of the popcorn. The design was used randomized entirely with five treatments and four repetitions, with the treatments being constituted of ratios different NH4 +: NO3 - (0/100, 25/75, 50/50, 75/25 and 100/0) and the experimental unit acted by a plant/vase. To the 45 DAS the plants were collected and appraised, as for the height, number of leaves, leave area, diameter the stem and matter total dry. The results obtained in this work evidence that plants of popcorn present a larger development when the supply of nitrogen is accomplished with application of this nutritious one in the form ammonium.

The objective of the present experiment was evaluate the effect inter cropping systems with the culture of the maize on the production components, aiming at to maximize the grain production and to increase availability of pastures for animal feeding. The treatments had consisted of the culture of DKB-950 maize (Hybrid Simple Modified), on three grassy species of (Brachiaria decumbens, Brachiaria brizantha and Panicum maximum cv. Tanzania) inter cropping systems and conventional tillege of soil. In foundation one applied 0, 35, 50 and 4 kg ha-1 of N, P, K and Zn respectively in the sulphate form of ammonium, simple superphosphate, potassium sulphate and zinc Sulphate. In covering it applied if 120 kg ha-1 of N. the used espaçamento was of 0,80 x 0,20 m, The experiment was arranged in a randomized complete block design, with four repetitions. The components of the production of the maize had not been affected by the studied systems of inter cropping, except for the number of spikes and production of grains, where the maize cultivated inter cropping systems with Brachiaria decumbens (4.787 kg ha-1) was better that the Tanzania (3.683 kg ha-1). The accumulation of dry mater presented significant difference between the treatments, in the which Tanzânia presented greater accumulates of dry mater.

Random regression models (RRM) allows considering heterogeneous residual variances to describe the growth for each age. However, this feature increases the number of parameters to be estimated in the maximization likelihood function process. Searching for more parsimonious RRM, several approaches have been suggested. One of them is the use of different structures of residual variances modelled through step function in different classes with similar variance or through variance functions. A total of 7,369 records of body weight of partridges, measured from birth to 210 days of partridges born from 2000 to 2004 were used in this research. The random regression models applied to the data set considered different structures of residual variances and were performed by the restricted maximum likelihood method. The residual variances were modeled using classes of 210 (R210) and 30 (R30) ages and variance functions with orders ranging from quadratic (VF2) to nine (VF9). The R30 considered birds weighted in the same week. The random effects included were the genetic additive direct and the permanent environment effects of the animal. It was not possible to include the maternal effects in the models. All random effects were modelled by sixth order regression on Legendre polynomials. The models were compared by the likelihood ratio test, the Akaike's information criterion and the Schwarz's Bayesian information criterion. Best results were showed by the models R210 and VF5. In conclusion, the most parsimonious model was VF5 and should be applied to fit growth records of partridges.

In the cemented plots, between July/93 and August/94, in the campus of the Federal University of Paraíba, in João Pessoa (lat 7o 02' 30'' S and long 3o 45' 06' W), experiments were carried out as follows: in the plots A, B and C podzolic soil was put into them and amended with 25kg of sugarcane bagass and added 80 earthworms (A), 10kg of bagass and 80 earthworms (B) and unamended and added 40 earthworms (C). The results showed that the sugarcane bagass improved same soil properties, by raising the pH and Ca++, organic C, S.O.M., and N levels. Microbial biomass (BM), in mg CO2-C.100g-1 of soil and microbial activity (MA), in g.year-1, showed a means: (A) BM= 7.88mg and AM= 1.54g; (B) BM= 10.44mg and AM= 1.59g; (C) BM= 3.29mg and AM= 1.25g. Ratio Cmic : Corg were higher in the plots with greater amount of sugarcane bagass (0.84% in A, 0.64% in B, and 0.33% in C). Earthworms population density (individuals.m-2) was initially 13 in the three plots and increased to 35 in A, 40 in B, and to 30 in C respectively. The results obtained here suggest that 10kg of sugarcane bagass enhanced soil microbial biomass and activity, and the earthworm population assayed.

For proposition of the better recovery practice is necessary to identify the main characteristics of index fingers soil of environmental degradation. For so much, it should seize upon chemical, physical and biological analyses. Thus, the goal of this work was to study some chemical indicators of environmental degradation in soils terms of semiarid. The soils were collected in the pilot's area JICA Project located in the municipal district of Pedro Avelino-RN, the choice of the area was due to your desertification degree. The analyses were accomplished in Soil, Plant and Water Analyses Laboratory of the University Semi-arid Rural Federal. The samples were collected in the layers of 5, 10, 20, 30 and 50 cm. The accomplished chemical analyses were: pH in water (1:2,5); Electric Conductivity (CE) in the extract 1:5; Ca+2,Mg+2, Na+ and K+ exchangeable, and P available. By the results, it verified that pH and CE increased with the depth, with regard to the contents of In the Na+ in the soil there was variation with the increase of the depth. To the thwart of the majority of the analyzed elements the K+ tended to decrease your content in the soil with the increase of the depth, The sodium elevated contents should be carried in consideration for the implantation of the recovery project, using itself preferentially resistant plants of sodicity.

The study was carried out in Fazenda Pau Ferro, Itaperuna - RJ, to evaluate soil quality attributes in pastures areas, Braquiária (Brachiaria brizantha (Hochst. ex A. Rich.) Stapf), Suázi (Digitaria swazilandensis Stent) and Tifton 85 (Cynodon spp. cv Tifton 85) cultivated in hill relief. Soil samples were collected at 0-10 and 10 -30 cm depth in two times; dry period (August of 2004, May of 2005 and August of 2005) and in the rainy period (December of 2004) in different sections: at the hillside shoulder (TS), backslope (TM) and footslope (TI) positions. In the samples soil chemical and physical analyses were accomplished. Were evaluated the soil aggregate stability; the bulk density (BD) and the total volume of pores (TVP), total organic carbon (TOC) and soil fertility. To study the multidimensional effect of soil attributes the Principal Component Analysis (PCA) was applied. The pastures areas showed a good aggregation levels, in the different times and depths evaluated. The grasses Tifton 85 and Braquiária propitiated a higher TOC contribution in the depth of 0-10 cm and also larger aggregate weight in the class> 2,0mm, in the dry period. Higher values of BD were observed in the TI. In the rainy period it was observed a BD reduction and TVP increase, mainly for the Suázi areas. In a general way, the positions of the hillside TS and TM were the ones that showed the higher values for the physical and chemical attributes indicating a better soil quality in these areas. In the TI area the lowest levels of soil quality were observed, possibly for the accentuated steepness of this last position of the slope in relation to the other positions. The PCA separated the areas in function of seasonal variation. The dry season presented the higher correlation values with soil quality attributes such as the aggregation indexes and TOC. The aggregate weight distribution in function of the size classes, especially > 2,0 mm, MGD, MWD and TOC were a indicative sensitive to the effects of the treatments, grasses types and seasonal variation.