Luciana Carvalho Santos

Características morfogênicas e estruturais de duas espécies de braquiária adubadas com diferentes doses de nitrogênio

The objective of this work was to evaluate the morphogenetic and structural characteristics of Brachiaria brizantha and decumbens submitted to different nitrogen doses (N). The experiment was carried in a greenhouse. The treatments consisted of four N doses (0, 75, 150 and 225 mg/dm3 of N) and two grasses (Brachiaria brizantha and decumbens). Nitrogen fertilization was subdivided into three applications. A completely randomized block experimental design with five repetitions was used. For the morphogenetic and structural characteristics, the daily foliar structure emergence, total number of leaves and number of tillers per B. decumbens plant was higher for B. brizantha. However, for phyllochron, the daily foliar prolongation and life duration of the B. brizantha leaf were higher. B. decumbens and brizantha responded increasingly up to 190 mg/dm3 of nitrogen in relation to the majority the available characteristics. The process senescence is accelerated with increase of the nitrogen doses, reducing the life duration of leaves.The objective of this work was to evaluate the morphogenetic and structural characteristics of Brachiaria brizantha and decumbens submitted to different nitrogen doses (N). The experiment was carried in a greenhouse. The treatments consisted of four N doses (0, 75, 150 and 225 mg/dm3 of N) and two grasses (Brachiaria brizantha and decumbens). Nitrogen fertilization was subdivided into three applications. A completely randomized block experimental design with five repetitions was used. For the morphogenetic and structural characteristics, the daily foliar structure emergence, total number of leaves and number of tillers per B. decumbens plant was higher for B. brizantha. However, for phyllochron, the daily foliar prolongation and life duration of the B. brizantha leaf were higher. B. decumbens and brizantha responded increasingly up to 190 mg/dm3 of nitrogen in relation to the majority the available characteristics. The process senescence is accelerated with increase of the nitrogen doses, reducing the life duration of leaves.

Características morfogênicas e estruturais do capim-tanzânia submetido a doses de fósforo e nitrogênio

The experiment was accomplished in a greenhouse from May to August of 2005, with the objective of to evaluate the effect of phosphorus and nitrogen fertilization on morphogenetic and structural characteristicas of Tanzania grass. The morphogenetic evaluations included leaf appearance, leaf elongation rate, and stem elongation rate. The structural evaluations measurements were: number of leaves, number of green leaves, number of tillers per plant, and final leaf length. It was used a complete randomized experimental design in 4 x 2 factorial scheme, being four phosphorus doses (0, 50, 100, and 150 kg of P2O5/ha) and two doses of nitrogen (0 and 100 kg of N/ha), with four replicates. It was utilized pots with 6.3 liters capacity each, leaving four plants per pot after staging. The N and P combination affected leaf elongation rate, stem elongation rate, number of tillers per plant, and number of green leaves per tillers. Nitrogen supply had a positive effect on leaf appearance rate, number of leaves, and final leaf length of tanzaniagrass. The majority of the studied variables were affected by the use of phosphorus when associated to N fertilization.

Caracterização de espécies diploides de Lotus em resposta à toxidez por alumínio

The objective of this work was to characterize diploid species, including Lotus japonicus model species and recombinant inbred lines of the Lotus genus for resistance to aluminum (Al) toxicity by using acid soil and nutrient solution. The experiments were conducted in greenhouse, being tested three diploid species (L. japonicus MG-20 and GIFU, L. filicaulis and L. burtii), and 180 recombinant inbred lines. In the experiments with diploid species, alfalfa was used as a check, and in the experiments with recombinant inbreed lines, GIFU model species was used. In the soil experiments, the morphological characteristics of the aerial part and the root were evaluated, and in the nutrient solution experiment, only the root length and growth were evaluated. MG-20 and GIF model species were the most productive in general. The results in nutrient solution followed the response pattern similar to the one observed in acid soil evaluations. The MG-20 genotype was superior to the others in all Al concentrations tested. Of the 180 recombinant inbred lines tested, 24 were superior and 39 inferior to the GIFU species. The great diversity observed in the model species and in the recombinant inbred lines can help in future selection of cultivated genotypes (tetraploids) inasmuch as they have a group of developed molecular markers which can be used at identification of regions responsible for higher or lower tolerance to aluminum toxicity.

Características morfogênicas de Braquiárias em resposta a diferentes adubações

The morphogenic characteristics of Brachiaria brizantha and Brachiaria decumbens were studied in function of different fertilization. The study was conducted in a green house evaluating two Brachiaria cultivars (B. brizantha cv. Marandu and B. decumbens cv. Basilisk) and five different fertilizations (no fertilizer, P, N, NP and NK). The assay was conducted in a 2 x 5 factorial scheme in a completely randomized design, with four repetitions. The morphogenic evaluations included leaf emergence, leaf elongation rates and filocron. The answer of the cultivars was quite expressive to the studied variables relative to nitrogen supply and its combination with phosphorus and potassium. The Basilisk grass was more productive than Marandu grass. The nitrogen importance as a tool to manipulate plant structure was evidenced.

Construção e avaliação agronômica de genótipos de cornichão com respostas contrastantes à toxidez por alumínio

The objective of this study was to select and characterize Lotus corniculatus genotypes with contrasting responses to toxicity by aluminum. Four cultivars (Sao Gabriel, San Gabriel, Draco, Estanzuela) and one population (UFRGS) were submitted to two consecutive selections in soils that presented 30-35% aluminum saturation. Selections consisted of separating 1% of the most and less vigorous individuals in order to obtain tolerant and sensitive genotypes, respectively. The individuals chosen were compared with the original germplasm by agronomical evaluation. Genotypes selected by tolerance to toxic aluminum were overall superior to the original populations. However, the materials chosen by sensitivity were inferior to the original populations even in situations where toxic aluminum was absent. Among the selected genotypes, the UFRGS selected for tolerance stood out, presenting an elevated dry matter production level - superior to all other genotypes. Field testing and seed multiplication of these genotypes for further use in areas that present this limitation is necessary, especially for the UFRGS population selected for tolerance to aluminum.