O objective this work was to estimated genotypic, phenotypic and environmental among traits of melon. Six hybrids of melon and their fifteen populations in diallel crosses were evaluated in a randomized complete block design with three replications. The traits assessed were yield, number total of fruits, average fruit weight, longitudinal diameter, transversal diameter, pulp thickness, pulp firmness and soluble solids content. The correlations between yield and total number fruit and yield and average fruit weight were positives. The total number exhibited negative correlation with average fruit weight and solids soluble content. The correlations of the solids soluble content with average fruit weight, pulp thickness and pulp firmness ware positives. However, pulp firmness and pulp thickness exhibited association negative. The undesirable associations detected in the present work were not sufficiently strong, indicating that is possible to obtain recombinants individuals in the segregating populations evaluated.

The objectives of this work were identified and characterize the allelopatic activity of extracts obtained from Arctium minus (Hill) Bernh (Asteraceae). The fitotoxic activity of organic extracts (1 e 100 mg.L-1) and aqueous extract (5,00 e 0,05% m/v) on the germination and radicular growth of the monocotyledon Sorghum bicolor L. (sorghum), and the dicotyledon Cucumis sativus L. (cucumber) were evaluated. The results showed the presence of allelopatic activity variable in according to the extract concentration and with the target plant. The intensity of induced inhibitory effect was higher for the ethanolic extract in concentration of 100 mg.L-1 for Sorghum bicolor L. The results also indicates the existence of the potential use of Arctium minus (Hill) Bernh ethanolic extract as a natural herbicide and open perspectives for the research of the constituent(s) with higher allelopatic activity.

The present work aimed to study the environment genotype interaction and estimate the componentssimple and complex of interaction as well as identify watermelon cultivars with phenotypic stability. Seven cultivars of watermelon were evaluated in six environments during the years of 1996, 1997 and 1998 in two location of Rio Grande do Norte State. The trait evaluated was the commercial fruits yield. The interaction Cultivar x Year wasn¿t significant, amount only to 3, 26 % of the total sum of square sum total of the source of variation. There wasn't interaction Cultivar x Location significant, however it explained 11,68 % of the total variation. The triple interaction was significant and explained 13,67 % of the total observed variation. The simple component was responsible for the most part of Cultivar x Environment interaction with about 61% of the total variation. The hybrid Jetstream had the best perfeormance with linear regression coeficient equal to unit, with regression deviation not significant, high coeficient of determination and average yield above the check.

In environmental studies is important to know the adsorption process of heavy metals in clay minerals, since they are able to immobilize these metals. Knowing the cations adsorption is influenced for several factors, the objective of this research was to study the copper adsorption process by bentonite clay and to evaluate the electrolyte type and pH influence on this process. In order to quantify the adsorbed copper, 2 g of bentonite clay were equilibrated for 24 hours with 20 mL of a NaNO3 (0,01 mol L-1) solution and with 20 mL of water containing different quantities of copper (5, 10, 20, 40, 60, 80, 100,120 mg L-1) as background solutions of pH values 4 and 6. Langmuir's adsorption equation in its linearized form was applied and the values of the maximum capacity and those of the constant related to the bonding energy were obtained. Langmuir isotherms presented two distinct adsorption regions at both pH 4 and pH 6, showing that the adsorptive phenomenon occurs in two distinct stages. The adsorption of copper depends on pH and ionic strength and it increased with an increase in pH and decreased slightly with an increase in ionic strength. The maximum capacity of adsorption and the bonding energy varied with the pH, with electrolyte used and with the adsorption regions.

The objective was to evaluate the horse behavior during the total time at leisure in testing of metabolism. Four male crossbred horses, with average age of eight years and alive weight of 376,09 kg, were used in an experimental delineation in Latin square (4 x 4), lodged in individual boxes. The treatments had been constituted by four diets: Alfalfa hay + Concentrated (ACSP); Tifton hay (low nutritional quality) + Concentrated (TCSP); Tifton hay (low nutritional quality) + Concentrated with Probiotic (TCCP); Alfalfa hay + Concentrated with Probiotic (ACCP). It was observed a statistical difference (P<0.05) in the percentages of total resting time, alert and head low, in the (ACSP) treatment, showing elevate value 76,85; 4,65 and 1.49%, respectively. The inquietude either showed a significative difference (P<0.05) showing values 5.29% for (ACCP) and (TCCP), respectively. The alimentary activities either showed a statistical difference (P<0.05) for (ACSP and ACCP), showing 10,45% average values. During prolonged resting times, the appeared of behavior disturbs were evident.

This study was conducted to evaluate the yield of two maize varieties cropped with organic and mineral fertilizations either associated or unassociated. The randomized experimental design was used under a factorial scheme 2 x 3 x 2, with four replicates. The first factor corresponds to two maize varieties (Nitrodent and Nitroflint), whereas the second one represents three levels of mineral fertilization: without mineral fertilizer; 300 kg/ha of 4-14-8 + 100 kg/ha ammonium sulfate (S.A.); and 600 kg/ha of 4-14-8 + 200 kg/ha S.A. The third factor represents two organic fertilization levels: without organic fertilizer; and 40 m3/ha organic compound. The experimental plot consisted of eight plant rows with 8m length each one and 1m spacing from each others, so totaling 64 m2 area. The yield of the maize grains by plot were evaluated, and the data were subjected to variance analysis (test ¿ 5%). The averages were compared by Tukey test at 5% probability level. Both varieties Nitrodent and Nitroflint only cropped under the organic system reached more than 6.500 kg/ha. The exclusive organic cropping system provided higher yields of maize grains, compared to the conventional system. No significant differences were found between the exclusive organic system and the combination of both organic and conventional systems upon the grain yield of the Nitrodent variety.

The soil fertility and plant nutrition are influenced by electrochemical reactions occurring on the surface of soil colloids. The point of zero salt effect (PZSE) is an important parameter to study the surface charge of those colloids, since, it allows to determine the net surface charge of soil particles. This paper aimed to determine the PZSE and the net electrical charge of twelve soils from Paraíba State, which samples were collected at the depth of 0-30 cm. The point of zero salt effect was determined using program computational PZSE for Windows version 1.0. The method adopted was the potentiometric titration with different ionic strength using electrolyte NaCl in concentrations 0.1; 0.01 and 0.001 M. The use of the program has a better analysis and accuracy of the values obtained for the PZSE, which ranged from 3.06 to 5.41. All soils had values of PZSE smaller than the pH in water, being, therefore, electronegative. All soils had the potential and the electrical charge negative, possibly due to the effect of organic matter once it presented significant correlation with PZSE.

In environmental studies is important to know the adsorption process of heavy metals in clay minerals, since they are able to immobilize these metals. Knowing the cations adsorption is influenced for several factors, the objective of this research was to study the zinc adsorption process by bentonite clay and to evaluate the particle size of clay and pH influence on this process. In order to quantify the adsorbed zinc, 2 g of bentonite clay, dried at room temperature and sieved at 0.5 and 2-mm-mesh, were equilibrated for 24 hours with 20 mL of water containing different quantities of zinc (10, 15, 20, 30, 50, 100, 150 and 200 mg L-1) as background solutions of pH values 4 and 6. Langmuir's adsorption equation in its linearized form was applied and the values of the maximum capacity and those of the constant related to the bonding energy were obtained. The results showed that Langmuir equation was adequate to describe zinc adsorption at different pH values and particle size of bentonite clay. Zinc adsorption in bentonite clay depended on pH and particle size, decreasing as they increased. The maximum retention capacity, 3.24 mg g-1, was obtained in pH 4 using particle size of bentonite clay < 0,5 mm.

The work was developed in a greenhouse, with the objective to evaluate the behavior of Sudan sorghum in one normal and another saline-sodic soil treated with increasing concentration solutions of calcium chloride. Two samples of Alluvial Soil proceeding from the half-barren part of Paraíba, Brazil, with salinity and sodicity problems had been used. The physical and chemical characterization of soil samples was carried and was mounted an experiment in randomized block type, at 2 x 6 factorial arrangement, being two soils and six solutions of calcium chloride with increasing concentrations, in three replicates. The soil had been conditioned in polyethylene vases with 5,0 kg of capacity, being submitted to the ticket of the solutions during sixty days, being then made a sampling for determination of the exchangeable sodium and the calculation of ESP. After this period, was planted one sorghum tolerant cultivar to salinity, being continued the ticket of the solutions under daily irrigation. At 60 days of application of calcium chloride solutions, it was observed that it had a reduction of the ESP, which continued being reduced until the 120 days, mainly for the saline-sodic soil, correcting the sodicity partially. The effect of the salinity had been evident in sorghum cultivated in saline-sodic soil, with problems since the germination in the treatments of lesser calcium chloride concentration, with improvement in the growth of the plants in the intermediate levels and decrease in the last level, probably, for the raised saline concentration, reflecting in the height of the plants and the production of dry matter.

Hydroponics is a method of culture which offers producers a larger number of cycles throughout the year, and value aggregated to vegetables. Empiricism, however, in the use of nutritive solutions, and the non-adoption of harvest times at which lower nitrate content can be achieved, may lead to a drop in produce quality due to the accumulation of nitrate. An experiment using a hydroponic method, the NFT, was conducted in the spring of 2003, in Jaboticabal, SP, aimed at evaluating nitrogen concentration in the nutritive solution (60,8; 121,6; 182,5; 243,5 mg L-1), rocket cultivars (Cultivada, Folha Larga and Selvática) and harvest time factors (7 a.m., noon and 5 p.m.) in nitrate content of rocket. The experiment was carried out in a randomized blocks design and a 4 x 3 x 3 factorial design, with four replications. For nitrogen concentration in the nutritive solution of 93 mg L-1, which showed higher MFPA, nitrate content was 598,4 mg kg-1 NO3 - fresh matter for rocket harvested at 7 a.m.