This work aimed to study the weed population dynamics of weeds and their influence to analyze in the corn production with the reduction of the space between lines in no-tillage system. The study was conducted in 2003/04 agricultural years, at the Experimental Station of Coimbra ¿ UFV. The experiment was conducted in a complete randomized block design. Treatments were arranged in a 3 x 3 x 2 factorial scheme with four replicates (three cultivars - UFVM 100, AG 9010 and AG 1051) three nitrogen application ways (0, 120 kg ha-1 of N in planting and 30 kg ha-1 at sowing + 90 kg ha-1 at four fully expanded leaves) and two plant spacing (1.0 and 0.5 m). For the phytosociological study, a square of 0.30 m of side was used, thrown at random once in each treatment before the application of the herbicides and 30 and 60 days after the application. The species with the highest density was Artemisia verlotorium, whatever the time of assessment and management used throughout the sampling dates. The population dynamics and the mass accumulation dries of the plants were not influenced by the spacing of the corn, for the nitrogen fertilization and for the studied cultivars. The spacing reduction, from 1.0 m to 0.50 m, provided an increase of 8% in grains productivity.

Concerning the different plant physiognomies of Brazilian semi-arid, the riparian vegetation is the least studied. With reference to this, there is a gap in comprehension of the influence of environments heterogeneity on the flora distribution. In order to evaluate the richness and species composition in distinct environments along a stretch of riparian vegetation of the Pajeú river, was performed a botanical survey in the municipality of Floresta, Pernambuco state. Samples were collected in six hectare. Were identified 78 species in 39 families in four environments: the fluvial terrace, the riverside, the small elevation and the tableland. Families with the greatest number of species were Leguminosae (sensu Engler) and Euphorbiaceae, similar to those reported in other Caatinga surveys. 52% of species collected were herbs. As expected, there were floristic differences between the gradient along the fluvial terrace to tableland, as a function of environmental heterogeneity. The tableland had the highest species richness while the fluvial terrace the lower.

The Alismataceae (excluded Limnocharitaceae) comprises twelve genera of herbaceous aquatic plants. Only two of its genera (Echinodorus and Sagittaria) are native to the Neotropics. A survey of the species of Alismataceae confirmed the occurrence of four taxa of Sagittaria and eleven of Echinodorus from the semi-arid region of northeastern Brazil. Analytical keys to differentiate the genera and species are provided, as well as illustrations of their taxonomic characteristics and data on their geographical distribution. Echinodorus macrocarpus to be considered synonymous with E. pubescens. Echinodorus reticulatus is considered as a different species from E. longipetalus. There are five excluded taxa from the Brazilian semi-arid region: E. grandiflorus, E. macrophyllus, E. martii, E. bolivianus, and E. decumbens.

The objective of this study was to compare the weather data obtained from both conventional (CWS) and automatic (AWS) weather stations, in Jaboticabal, SP, Brazil (latitude: 21º14'05" S, longitude: 48º17'09" W and altitude: 613,68m), from July 1997 to June 2002. Daily data were collected and analyzed statistically by regression analysis. The results showed a good relationship between CWS and AWS, specially for air mean temperature, minimum temperature, maximum temperature and rainfall. Air humidity and atmospheric pressure showed the highest errors, respectively equal to 5,69% and 3,64 hPa. Wind velocity at 2m did not show good precision and accuracy because its estimation for CWS.

The objective of this work was to study the behavior of ten soybean [Glycine max (L.) Merr.] cultivars using the electrical conductivity (EC) test by the comparison of curves of the accumulative electrolyte leakage along the time and to establish the statistical model that allow the best adjust of the curves. Ten soybean cultivars were used and they were mechanically harvested in 2004 in the EEA Oliveros, Santa Fe, Argentina. Measurements of EC were made for 100 individual seeds of each cultivar during 20 hours of immersion at intervals of 1 hour using an equipment that permit an individual seed analysis (Seed Automatic Analyzer SAD 9000S). There were proposed two statistical models to study the EC along the time of the 10 cultivars studied using SAS Statistics Program, to select the model that better allow us to understand the EC behavior along the time. Model 1 allowed to make comparisons of EC along the time between cultivars and to study the influence of the production environment on the physiological quality of soybean seeds. The time to reach the stabilization of the EC must not be lower than 19 hours for the different cultivars.

Some physical and chemical characteristics of Mimosa caesalpiniaefolia Benth. wood were analyzed in order to study its potentiality as alternative specie to produce tannins. The polyphenols (tannins) were avaliated by Stiasny reaction. The wood from this specie showed an average of 41.1% and 58.9% for heartwood and sapwood respectively. The average quantity of extracts was 9.0%. The contents of cellulose, hemicellulose and lignin were 32.8%, 33.2% and 24.6% respectively. The averages of polyphenols (Stiasny index) for heartwood and sapwood, were 96% and 42% respectively. The highest tanni ns content was in the heartwood with content of 11.5%. The results showed that is possible to use Mimosa caesalpiniaefolia as a source of condensed tannins.

The aim of this work was to evaluate methods for overcoming Jitirana's (Merremia cissoides) seeds dormancy. The treatments were: immersion of Jitirana's seeds in sulfuric acid during 20, 25, 30, 35, 40, 45, 50, 55 and 60 minutes and control (no treatment). The experiment was carried out in the completely randomized design, with ten treatments and four replications, with 20 seeds each. The variables evaluated were: germination percentage, germination speed index, medium time for germination, dry weight and height of seedling obtained 16 days after sowing. The immersion of seeds in sulfuric acid during 50 minutes is an efficient method to overcome dormancy and promotes germination, enabling quickly and greater Jitirana's seedling emergence.

The experiment was carried with the objective of evaluating the adaptability of the breeds goats to Semiárid through physiologic parameters: rectal temperature, respiratory frequency and surface temperature and the structures of the tegument: perspiration glands, fat of glands and hair follicles. 40 female were used goat, of the breeds Anglo-Nubiana, Savana, Boer and Moxotó, being 10 animals of each breed, with medium age of five months. For the physiologic answers, he animals were allocated into a completely randomized design entirely in portions subdivided in the time, with the main treatments constituted by the breeds and the secondary ones by the shifts. For the study steorologic of the tegument was used in a completely randomized design entirely with four treatments and three repetitions. There was in significant teraction (P<0.05) between breed and shift, for the rectal and surface temperature. The breed Savanna it presented larger medium (P<0.05) for respiratory frequency and the Anglo-Nubiana to medium smallest (P<0.05). There was significant difference (P<0.05) regarding the number of hair follicles for breed Anglo-Nubiana that presented the smallest number, differing significantly (P<0.05) of the breeds Savanna and Moxotó that presented the largest averages, however these didn't differ (P>0.05) of the Boer breed. The breed Anglo-Nubiana it presented larger number of glands perspiration (P<0.05) and the breed Savanna presented the largest average of fat of glands (P<0.05). The studied breeds demonstrated to be physiological well adapted and with characteristics of the favorable tegument to the climatic conditions of semiarid.

Today there is still a search for substrates economical, easy to use, available in large quantities and good characteristics for the production of seedlings, so are many substrates available. Thus, an experiment was conducted using different substrates for the production of yellow passion fruit seedlings at the University Vale do Rio Doce in Governador Valadares - MG, from November 2007 to January 2008. The objective was to evaluate different commercial substrates and a substrate used by small farmers in the region, associated with different rates of mineral fertilizer 8-28-16 (0, 21.4 and 42.8 g / plant) on the initial growth of two new cultivars (FB100 and FB200). We evaluated the physiological characteristics of seedlings. It was found that the cultivar FB 200 had the best vegetative growth, the substrate manure + soil was the best for cultivar FB 200, together with the plantmax® was superior to coconut fiber in the initial growth of cultivar FB 100 and the increasing rates of fertilizer stimulated the growth of seedlings.

Lettuce has highlight as an important crop for human consumption, to having good flavor and important nutritional characteristics and potassium is one of the main nutrients that crop. This work aimed to evaluate the influence of potassium in morphological and physiological lettuce responses in South of Tocantins State. The experimental design was randomized block in factorial scheme of 4 x 6 with three replications. Four levels were evaluated of K2O: 0; 100; 200 and 300 kg ha-1 in six development stages: 15; 22; 29; 36; 43 and 50 days after emergency. Was determine the specific leaf area, net assimilation rate, relative growth rate and abso-lute growth rate, as well as the leaf, stem and root weight. During the duration of the experiment occurred high temperatures that caused a physiological disorder known as tipburn, which compromises calcium uptake by the plant. The potassium levels did not influence the morphological and physiological responses of lettuce as well did not significant differences among levels for leaf, stem and root weight. The partition of assimilates in the plants was influenced by crop management whit significant variation among evaluation times.