Juliana Sobreira de Souza

Influência da posição das miniestacas na qualidade de mudas de cedro australiano e no seu desempenho inicial no pós-plantio

The Toona ciliata (Australian cedar), originated from Australia showed high acclimatization in Brazil, where it found appropriate conditions for its growth, particularly in southern Bahia and throughout the southeastern region. However, the plantings presented irregular stems. Besides the seeds are a limiting resource, in result of their production seasonality and short viability period. This study aimed the evaluation of the quality of cuttings grown from 6 cm length apical, middle and basal mini-cutting positions of the sprouts of the mini-strains - from seminal origin - and the initial growth of cuttings. It was established a multi-clone mini-garden containing a total of 284 mini-strains. After cutting off the sprouts of the seedlings - to originate the mini-strains - the mini-cuttings from the above different positions were collected. At the lifting time of the rooting sector, dry mass weight of shoot and root, length, diameter, number of adventitious roots and survival data were collected. The height and diameter were monitored fortnightly, starting from 80 days after the staking of the mini-cuttings. At the end of the production cycle, the dry mass weight of shoot, the root number, the diameter and the length of root cuttings were evaluated. Thirty percent of the cuttings were transplanted to pots of 3.8 L, in the open air where the height and basal diameter, the dry mass of shoot, the leaves and the roots were measured 60 days after the transplanting. Cuttings originated from the basal mini-cuttings at the end of the lifting time of the rooting sector, showed the highest height and diameter, however no difference was pointed out regarding to the basal diameter of cuttings originated from the middle position. There were no differences related to the shoot dry mass and the adventitious root number, the dry mass weight, the total length and the diameter of the adventitious roots of cuttings in relation to the mini-cutting positions in the sprouts. The survival was high, averaging 94.7 % for the apical, 96.3 % for the middle and 96.6 for basal position. Sixty days after transplanting, despite the differences in the diameter and the height of the cuttings at the end of the nursery phase, no difference in the height, the diameter and the dry mass weight of shoots, the leaves and the roots as pointed out in the treatments.

Enraizamento de miniestacas e produtividade de minicepas de cedro australiano manejadas em canaletões e tubetes

The planted forest stands aim to supply the growing demand for wood, especially for the sawing and veneer industries, that exclusively used wood from native forests. The Australian cedar (Toona ciliata) belongs to the family Meliaceae, is the species of interest for this sector. Studies with the Australian cedar propagation have carried out in latest years, mainly involving the use of mini-cuttings due to the need for high quality cuttings. The objectives of this paper were to evaluate the rooting and the productive capacity of Australian cedar mini-strains, managed in lifted seedbeds and 180 cm3 plastic tubes systems. So, two mini-clone gardens were set up. The mini-strains of both gardens were grown from cut-off seedlings originated from seeds. Successive collections of sprouts were carried out to get the mini-cuttings. Afterwards, they remained in the rooting area under intermittent mist. Thirty days later the rooting characteristics of the cuttings originated from both mini-gardens were evaluated. The period of permanence of the cuttings in the gardens was seven-month long. During this period, six collections from the lifted seedbed and four from the plastic tubes were carried out. The mini-strains in the two systems showed 100 % of survival rate. At the end of this seven-month period, an increasing tendency of the average number of mini-cutting was found out in both systems. Those from the lifted seedbed showed more productivity than those ones from the tubes. The plants from the mini-cuttings of the tube showed higher number and length of adventitious roots at the end rooting stage

Aplicação das concentrações e proporções de nutrientes no diagnóstico da eutrofização

This review adresses the application of concentrations and ratios of nutrients (nitrogen and phosphorus) in the diagnosis of eutrophication in natural waters. We present a brief history of eutrophication and considerations on eutrophicating elements. The use of ratios in the diagnosis of eutrophication has limitations, since there are other parameters that prevent the proliferation of phytoplankton even under optimal nutrient conditions. Assays are used to identify the nutrient limitation to phytoplankton growth, while the trophic state index is used to assess the state of nutritional enrichment of an aquatic ecosystem. This work highlights the importance of the diagnostic study of eutrophication in natural waters subjected to the human impact, and suggests actions to improve their conditions, such as protection of riparian areas, terracing of agricultural areas, use of the required amount of fertilizer, and treatment of effluents from sewage to reduce the loads of N and P for lotic environments.

Growth and quality of australian cedar saplings originated from different multiclonal minigarden systems

Forestry researchers often evaluate minicutting vegetative propagation of Australian cedar (Toona ciliata) as a viable technique for this species. However, the adoption of minigarden systems for commercial propagation still requires viability and quality testing of saplings produced after multiple harvests. In the present work, we evaluate survival, growth, and quality of Australian cedar saplings grown from minicuttings originating from multiple harvests of ministumps planted in gutter or tube systems. Experiments were conducted in a greenhouse using a completely randomized design with a 2 × 4 factorial treatment structure (two minigarden systems and four minicutting harvests). For the gutter system, six minicutting harvests were performed 50, 86, 115, 149, 177 and 212 days after planting ministumps, whereas for the tube system, four harvests were performed 115, 149, 177 and 212 days after planting ministumps. At the end of each sapling production cycle (105 days after each minicutting harvest), saplings were evaluated for survival, foliar area, dry mass of aerial parts, number and length of adventitious roots, dry mass of the root system, height to diameter ratio, ratio between the dry mass of aerial parts and dry mass of root system, and Dickson’s Quality Index. Sapling survival was not affected by minigarden system, except for a reduction observed in fourth cycle saplings from the tube system. Sapling quality was also similar between systems. However, sapling growth potential decreased with production cycle, indicating that ministumps lose vigor with multiple harvests.

Application of concentrations and proportions of nutrients in the diagnosis of eutrophication

Esta revisao aborda a aplicacao das concentracoes e proporcoes de nutrientes (nitrogenio e fosforo) no diagnostico da eutrofizacao em aguas naturais. Foi realizado um breve historico sobre a eutrofizacao e consideracoes sobre os elementos eutrofizantes. O uso das razoes no diagnostico da eutrofizacao apresenta limitacoes, uma vez que existem outros parâmetros que impedem a proliferacao do fitoplâncton mesmo em condicoes otimas de nutrientes. Os bioensaios sao utilizados para identificar a limitacao de nutrientes ao crescimento fitoplanctonico, enquanto o indice de estado trofico e utilizado para avaliar o estado de enriquecimento nutricional de um ecossistema aquatico. Este trabalho destaca a importância do estudo de diagnostico da eutrofizacao nas aguas naturais submetidas aos impactos decorrentes da acao humana e sugere acoes para melhoria de suas condicoes, como a protecao de matas ciliares, terraceamento de areas agricolas, a utilizacao da quantidade necessaria de fertilizantes e o tratamento dos efluentes oriundos dos esgotos para reduzir as cargas de N e P para os ambientes loticos.