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Rustificação de plantas jovens de Coffea arabica L
(Universidade Federal de São Carlos, 2007-06-06) Novaes, Paula; Prado, Carlos Henrique Britto de Assis; https://lattes.cnpq.br/7561749470600567; https://lattes.cnpq.br/1499847216040850
Young plants of Coffea arabica grafted over C. canephora were submitted to six watering cycles (WC) during 35 days. Each WC was accomplished until net photosynthesis (PN) close to zero or leaf water potential (Ψ) close to -2.0 MPa in Acauã (AC), Mundo- Novo (MN), and Obatã (OB) cultivars. After 2 WC (about 10 days) gs dropped from 0.15 to 0.01 mol m-2 s-1 in all cultivars changing the pattern of leaf gas exchange in subsequent WC. From 3 to 6 WC the cultivars showed high oscillations of water use efficiency or substomatal CO2 concentration (Ci) besides negative PN at the end of WC. After 3 WC, gs increased faster than PN after watering and Ci increased indicating some damage in photosynthetic machinery. It happened strongly in OB, which showed progressive reduction of PN after 3 WC and the lowest values of Ψ (-2.0 MPa) at the end of 6 WC. The survivorships for cultivars were 80% till 3 WC and 70% after 6 WC. The gas exchange pattern alteration could indicate the potential hardening of AC, MN and OB cultivars. After field plantation of hardened and control (without perivous hardening) Mundo-Novo and Obatã cultivars, with 180-days-old, it was observed significant (p<0.05) greater accumulation of leaf, stem and root biomass in hardened in control plants. Stem diameter, height and the number of leaf and branch were also higher (p<0.05) in previous hardened individuals. Greater differences in crown structure and biomass between control and hardened plants were observed mainly after the first period of low water availability (210 days under field conditions). The higher leaf number and leaf area in more branched crowns could carbon assimilation and grain production. For practical proposes, 3 WC before growing under field conditions are sufficient for changing consistently the leaf gas exchange pattern in 3 cultivars studied, keeping photosynthetic machinery free of damage and high survivorship. Previous hardening proportioned less interrupted vegetative development after transplantation under field conditions in both cultivars.
Reconstrução de superfícies 3D a partir de nuvens de pontos usando redes neurais auto-organizáveis
(Universidade Federal de São Carlos, 2007-06-06) Mari, João Fernando; Saito, José Hiroki; https://lattes.cnpq.br/7065615446493390; https://lattes.cnpq.br/3582704696209050
This work consists of the implementation of a 3D surface reconstruction algorithm from point clouds, using Self-Organizing Neural Networks. Among the Neural Networks the SOM (Self-Organizing Map) is distinguished, since it is a self-organized model based on competitive learning. The proposed system is based on the GCC (Growing Cell Structures), a self-organizing neural network that is a SOM incremental variation with some alteration in the way that the positions of the direct neighbors of the winner node are updated, and also in the way that new nodes are inserted and inactive nodes are removed. The system has been improved by the inclusion of the edge-swap operation, improving the quality of the generated mesh and the convergence of the algorithm. The algorithm than has been called GCS-M (GCS-Modified). To evaluate the results obtained by the implementation of the proposed system had been used metrics to evaluate the quality of the mesh, based on the values of the minimum distances between the point cloud and the elements that compose the polygon mesh. With this comparison mechanism, it had been performed comparisons of the GCS-M algorithm results and the traditional methods results of surface reconstruction. The obtained results show that the proposed algorithm is very efficient, obtaining realistically reconstructed surfaces with low error measures.
Macrófitas aquáticas submersas: fotossíntese, crescimento e variáveis abióticas da água
(Universidade Federal de São Carlos, 2007-06-06) Pezzato, Maura Maria; Bianchini Júnior, Irineu; https://lattes.cnpq.br/0659731944736389
Cabomba furcata and Egeria najas are rooted submerged species of aquatic macrophytes that occurred in Oleo Lagoon (21° 36 S e 47° 49 W), Mogi-Guaçu river floodplain (Ecological Station of Jataí, Luiz Antônio, SP). Limnological characteristics of the water and the net photosynthesis of C. furcata were determined in Oleo lagoon at the rainy and the dry periods (summer and winter, respectively); aiming to evaluate the influence of abiotic variables on photosynthetic rates in situ. The dry season, the lagoon s water was highly transparent, conversely, at the rainy season, the water presented high amounts of suspended matter, which decreased the water transparency. In laboratory, experiments were performed with C. furcata and E. najas to verify the influence of pH and light on net photosynthetic. Besides, the effect of temperature on growth rates and net photosynthesis were analyzed for E. najas. Photosynthesis rates were determined by changes in dissolved oxygen concentration using the light and dark bottles technique (Winkler´s method). The growth rates were estimated by increment of biomass. The abiotic variables examined and the net photosynthesis of C. furcata presented clear seasonal pattern. C. furcata and E. najas were capable to use only free CO2 dissolved in the water. Both species showed adaptability to low intensities of light and perhaps considered shade species. Nevertheless, C. furcata presented lower values of Ks than E. najas (25 and 55 µmol m-2 s-1, respectively), probably because it is less tolerant to high light intensities. The optimal temperature for E. najas growth rate was 25 ºC; with generally higher biomass gain between 20 and 30 ºC. The largest values of net photosynthesis of E. najas were obtained to 25 ºC, independent of the temperature it was acclimated (15 - 30 ºC). The processes of photosynthesis and growth of E. najas presented low sensibility to the temperature increase (Q10 = 1.85 and 1.17, respectively).