Larvae from two Nile tilapia (Oreochromis niloticus) lineages were subjected to different storage densities. An experiment was conducted arranged in a 4 x 2 factorial scheme, four storage densities (6.25, 12.50, 18.75 and 25.00 larvae L-1) and two lineages (GIFT and Thai). Larvae from the lineage GIFT and Thai (4,000) were distributed in 32 aquariums with 8 liters of water each, in a randomized order with four replications. The larvae were maintained in the aquariums with constant aeration and natural photoperiod for 36 days. Limnological variables were within the proper range to the specie. Data were subjected to ANOVA, and the Tukey test was used for the density effects. Regarding the biological variables, there was no interaction between lineage and density. The GIFT lineage presented better performance on total length and biomass at the 36th day. Regarding the densities of each lineage, the greater length, weight and weight gain results were found with a density of 6.25 larvae L-1, however, an increase in biomass and a space use optimization occurs using 25 larvae L-1. Therefore, the lineage GIFT at density of 25.00 larvae L-1 is indicated for larval culture.

Com objetivo de resgatar germoplasma de Cucurbita spp. da agricultura familiar do estado do Rio Grande do Norte, quantificar a variabilidade fenotípica e identificar as principais espécies cultivadas, foram organizadas 17 expedições para coleta de acessos, nos municípios de Baraúna, Rio do Fogo e Touros (principais fornecedores de frutos para o comercio estadual) e de mais oito municípios de diferentes microrregiões do Estado (Apodi, Caraúbas, Ceará Mirim, Cerro Corá, Currais Novos, João Câmara, Lagoa Nova e Macaíba). Cada acesso coletado foi composto por um fruto ou aproximadamente vinte sementes fornecidas pelo próprio agricultor. Todos os acessos foram identificados quanto à espécie botânica e realizados os procedimentos de acondicionamento, identificação e armazenamento das sementes em câmara fria para preservação do material. Uma amostra dos acessos coletados como frutos e uma pequena parte dos acessos obtidos como sementes da espécie C. moschata foram multiplicados usando-se autofecundação das plantas. Plantas e frutos foram caracterizados preliminarmente com auxílio de descritores morfológicos. Resgatou-se acessos em todos os municípios visitados, sendo 112 de C. moschata e 50 de C. maxima. Verificou-se predominância do cultivo da espécie C. moschata bem como constatou-se grande variabilidade para vários descritores de planta e fruto nos acessos que foram caracterizados.

The objective of this work was to develop empirical models for hydraulic performance of drippers operating with cashew nut processing wastewater depending on operating time, operating pressure and effluent quality. The experiment consisted of two factors, types of drippers (D1=1.65 L h-1, D2=2.00 L h-1 and D3=4.00 L h-1), and operating pressures (70, 140, 210 and 280 kPa), with three replications. The flow variation coefficient (FVC), distribution uniformity coefficient (DUC) and the physicochemical and biological characteristics of the effluent were evaluated every 20 hours until complete 160 hours of operation. Data were interpreted through simple and multiple linear stepwise regression models. The regression models that fitted to the FVC and DUC as a function of operating time were square root, linear and quadratic, with 17%, 17% and 8%, and 17%, 17% and 0%, respectively. The regression models that fitted to the FVC and DUC as a function of operating pressures were square root, linear and quadratic, with 11%, 22% and 0% and the 0%, 22% and 11%, respectively. Multiple linear regressions showed that the dissolved solids content is the main wastewater characteristic that interfere in the FVC and DUC values of the drip units D1 (1.65 L h-1) and D3 (4.00 L h-1), operating at work pressure of 70 kPa (P1).

The Cerrado occupies 25% of the Brazilian territory and is the second largest biome in South America, second only to the Amazon Rainforest. Hence, studies on the native species of the Cerrado are important for implementing conservation strategies. In this context, knowledge of the requirements and conditions for germination of seeds of these native species is essential. The Cerrado watermelon ( Melothria campestris (Naudin) H. Schaef. & S.S. Renner) is a plant that is not cultivated, but has been used in revegetation projects in the countryside of the Cerrado because its fruits are fed upon by fauna in times of food shortage. The purpose of this study was to determine the most appropriate methodology for the germination of the Cerrado watermelon, by identifying the best - suited substrate, the optimal temperature, and the corresponding time taken for germination . The treatments consisted of four substrates: in a paper roll, on paper, in sand, and on sand; and four temperatures: 20, 25, and 30 °C (maintained constant), and a fourth temperature treatment that alternated 20 - 30 °C. The effect of the substrates and temperatures on seed performance was evaluated using the germination test, speed index, and average time for germination. The experimental design was fully randomized, with treatments distributed in a 4 × 4 (substrates × temperatures) factorial scheme, with four replications. Our results show that the temperature of 20 °C had a negative influence on germination in all substrates. Further, we found that the germination of the Cerrado watermelon seeds was best in a paper roll or on sand substrate, maintained at a constant temperature of 30 °C, or when temperature was alternated 20 - 30 °C, and the time required for germination stabilization was 30 days.

Prickly palm cactus husk was used as a solid - state fermentation support substrate for the production of cellulolytic enzymes using Aspergillus niger and Rhizopus sp. A Box - Behnken design was used to evaluate the effects of water activity, fermentation time and temperature on endoglucanase and total cellulase production. Response Surface Methodology showed that optimum conditions for endoglucanase production were achieved at after 70.35 h of fermentation at 29.56°C and a water activity of 0.875 for Aspergillus niger and after 68.12 h at 30.41°C for Rhizopus sp. Optimum conditions for total cellulase production were achieved after 74.27 h of fermentation at 31.22°C for Aspergillus niger and after 72.48 h and 27.86°C for Rhizopus sp . Water activity had a significant effect on Aspergillus niger endoglucanase production only. In industrial applications, enzymatic characterization is important for optimizing variables such as temperature and pH. In this study we showed that endoglucanase and total cellulase had a high level of thermostability and pH stability in all the enzymatic extracts. Enzymatic deactivation kinetic experiments indicated that the enzymes remained active after the freezing of the crude extract. Based on the results, bioconversion of cactus is an excellent alternative for the production of thermostable enzymes.

Cowpea ( Vigna unguiculata (L.) Walp.) is widely cultivated in northeast Brazil for production of both green grains and dry grains. Green grains are cowpea grains with a 60 to 70% moisture content that are very appreciated by the local people. The cultivation of cowpea in northeast Brazil is performed mostly using landraces and the low yields achieved in some areas of that region are generally attributed to the cultivation of less productive landraces. The objectives of this research were to identify the best landraces in terms of green bean yield and the characters that hold the most positive direct effects on this yield via path analysis. Twelve landraces of undetermined growth were evaluated in two experiments conducted in Mossoró, Brazil. The first experiment (E1) was sprinkler - irrigated and the second (E2) was conducted under rainfed conditions, but was irrigated whenever necessary. Pod yield and dimensions and green grains were evaluated, in addition to the main grain yield components. A randomized block design with five replications was used. The data presented here identified eight landraces with the highest yields. In addition, cowpea yield was higher in the dry season (E1) than in the rainy season (E2). The number of pods per plant had the largest direct positive effect on green grain yield.

A major problem affecting some upland rice cultivars is the increase in plant size when subjected to high doses of nitrogen fertilizer, leading to high levels of lodging. A method to reduce the height of upland rice, and therefore lodging, would be to use plant growth regulators. However, little information exists on the effect of these regulators on plant physiological processes. Therefore, the objective of this study was to evaluate the influence of trinexapac-ethyl application in upland rice via analysis of growth and gas exchange. The experiment was carried out under greenhouse conditions using the BRS Primavera cultivar. A completely randomized design with eight replications was used. Treatments were carried out with and without the application of the plant growth regulator, and plants were subject to two-stage assessments in which physiological and gas-exchange indices were measured. The use of trinexapac-ethyl improved the growth of rice plants from the flowering to the physiological maturity stage, resulting in higher values of leaf area ratio, specific leaf area, and leaf matter ratio in treated plants. At the same time, it provided smaller reduction in net CO2 assimilation at the physiological maturity stage. Thus, net/apparent assimilation rate did not change after the application of growth regulator, but relative growth rate decreased in these treated plants. These results indicate the occurrence of self-shading in rice plants induced by what might be a supra-optimum trinexapac-ethyl concentration.

The Rules for Seed Analysis and the Instructions for Seed Analysis of Forest Species have no recommendations for conducting the S. tenuifolia germination test. Therefore, the aim of the present study was to evaluate different temperatures and substrates to perform the germination test of S. tenuifolia seeds. The experimental design was completely randomized in a factorial 4 × 3 design and consisted of four substrates (paper roll; on paper; on sand and on vermiculite) and three temperatures (25, 30 and 35 °C), with four replicates of 25 seeds. The percentage of normal seedlings, the germination speed index, the shoot length, root length and dry mass of seedlings were evaluated. The Tukey test was used at 5% probability. There was a significant interaction between the temperatures and substrates tested for all variables, indicating that there is at least one ideal combination of the two factors that can increase the germination of seeds. The germination and vigor of S. tenuifolia seeds are influenced by the temperature and by the substrate used in the germination test. The combination of the paper roll substrates with a temperature of 25 and 30 °C was suitable for the germination of S. tenuifolia seeds.

Nitrogen fertilization is a common practice used to increase the yield of winter bean crops. However, this practice leads to excessively tall and prostrate plants that have too many leaves, resulting in self - shading, and low yield and grain quality. The use of growth regulators could minimize the undesired effects of nitrogen fertilization. This study aims to determine the optimal concentration of paclobutrazol (PBZ) for inhibiting bean growth using the cultivars BRS Pontal and BRS Supremo. The plants were treated with PBZ at different concentrations, and also in combination with ammonium sulfate ten days after fertilization. The height and yield of plants were evaluated. It was observed that PBZ at 8 mg L - 1 effectively inhibits the growth of bean plants, and increases the number of pods and grains. Higher concentrations of PBZ proved to be phytotoxic. Additionally, the application of PBZ ten days after fertilization with ammonium sulfate did not suppress the overgrowth of bean plants, and did not affect their yield.

Corn is a nitrogen-intensive crop, and the use of management practices such as inoculation of the seed with diazotrophic bacteria, which can maximize crop productivity and reduce the need of nitrogen fertilizers, may result in lower production costs. The present study aimed to evaluate the effect of inoculation of corn seed with Azospirillum brasilense and controlled addition of nitrogen to topdressing on the nutrition, production components, and productivity of crop grain. The experimental design was a randomized block design, with four replications in a 2 × 5 factorial scheme. The treatments consisted of inoculation or not of corn seed with A. brasilense (at 100 mL per 25 kg of seed) and five nitrogen (N) levels in topdressing (0, 30, 60, 90, and 120 kg N ha-1 from urea [45% N]) were applied when the corn was in the phenological growth stage V6. Foliar macronutrients, foliar chlorophyll index (FCI), production components, and yield of corn grain were valuated. Inoculation of corn seeds with A. brasilense increased plant height and grain yield. Fertilization in topdressing, with N levels up to 120 kg ha-1, linearly increased the foliar nutrients and productivity of corn cultivated in the spring/summer in the low-altitude Cerrado region of Brazil.