Felipe Turchetto

Silvicultural Potential of Handroanthus heptaphyllus Under Doses of Controlled Release Fertilizer and Container Volume, in Nursery and in the Field

The present study aimed to characterize the growth of Handroanthus heptaphyllus seedlings in a nursery, planted under different container volumes and doses of controlled release fertilizer (CRF), and to verify whether the responses obtained in the nursery are confirmed in the field. For the production of seedlings in the nursery, three volumes of container (180 and 280 cm3 polypropylene tubes and 500 cm3 polyethylene bags) and four CRF doses (0, 4, 8, and 12 g L-1 of substrate) were used. At 180 d after emergence, height (H), stem diameter (SD), H:SD ratio, shoot dry weight, root dry weight, total dry weight, Dickson Quality Index, leaf area, root length, and fluorescence of chlorophyll a were evaluated. The same treatments were evaluated again in the field 540 d after planting, and the survival, increase in H and SD, as well as shoot dry weight, leaf area, chlorophyll fluorescence, and chlorophyll index (a, b and total) were measured. In the nursery, seedlings of H. heptaphyllus responded positively to the volume of the container, as well as the base fertilization using CRF. However, when planted in the field, the plants that received the best nutritional conditions in the nursery showed good performance and was favored in the field. Thus, in the production of quality seedlings, the use of containers of the type polypropylene tubes with 180 cm3, and basic fertilization with 12 g L-1 of CRF conditions that enable growth of H. heptaphyllus in the field are recommended.

Seed Analysis and Seedling Production of Matayba elaeagnoides Radlk

The objective of this study was to evaluate the germination potential of Matayba elaeagnoides seeds, identifying the best substrate for laboratory analysis and to determine seedling emergence and growth under different shade levels in the nursery. Different substrates (paper roll, between and on blotting paper, and on sand or vermiculite) were evaluated in the germination test and different shade levels (0, 30, 50 and 75%) were tested in the nursery. No differences were found between the substrates for seed germination, however, the highest germination percentage was observed when using paper roll (70%). The 30, 50 and 75% shading intensities positively influenced Matayba elaegnoides seedling emergence, however, the best performance in nursery growth was observed under 75% shade presenting seedlings with better standard and quality.

IMPACT OF SEEDLING REMOVAL ON NATURAL REGENERATION IN THE SOUTHERN ATLANTIC FOREST REMNANT

The use of a forest seedling bank has been recommended as an alternative to increase species richness in forest nurseries, as well as to produce seedlings of species that are diffi cult to propagate, especially those that belong to the late secondary and climax successional groups, which are not as commercially available. However, little is known about the impact of this method on forest dynamics. Thus, the present study aimed to examine the resilience and dynamics of a seedling bank in a remnant of a subtropical seasonal forest belonging to the Atlantic Forest Biome when subjected to different intensities of seedling removal. The experiment was conducted in a random block design in a factorial scheme (5 × 4), with treatments composed of fi ve intensities of removal of individuals from the seedling bank and the four seasons. The treatments were distributed into 18 blocks and the experimental units were composed of 1 m × 2.5 m plots. The resilience of the seedling community was assessed by examining effects of the fi ve removal intensities. The dynamics between the evaluation periods within each treatment were verifi ed by comparing the number of species and seedlings present before the treatments with those in the other evaluation periods. After one year, we found that tree-shrub vegetation had a partial capacity for restoration after withdrawal of individuals from the seedling bank. Our results show that the impact on the regeneration community can absorb the effects of up to 25% seedling removal. The technique of seedling transplantation may be recommended for species that have abundant regeneration, such as Actinostemon concolor, Eugenia rostrifolia, Trichilia claussenii and Nectandra megapotamica. v.24 n.2 2018 IMPACT OF SEEDLING REMOVAL ON NATURAL REGENERATION IN THE SOUTHERN ATLANTIC FOREST REMNANT

REUTILIZATION OF RESIDUES AS COMPONENTS OF SUBSTRATE FOR THE PRODUCTION OF Eucalyptus grandis SEEDLINGS

Increased production of agro-industrial waste is a global concern, requiring proper disposal. In this sense, they can represent alternative sources for substrate production, adding value to the materials and reducing the cost of seedlings in the nursery. However, their proportions in the mixture should be adequate for better use of water and nutrients, ensuring better seedling quality. The objective of this study was to identify the potential of rice husk and peach kernel residue, as a secondary substrate component, for the production of Eucalyptus grandis seedlings. The carbonated (CRH), hydrolyzed (HRH) rice husk and crushed peach kernel (CPK) were added at 0, 10, 20 and 30% to an organic substrate. The results were submitted to analysis of variance and correlation analysis between the variables of the substrates and the morphological and physiological attributes. The results indicated that the HRH and CPK can add value to the agro-industrial residue when mixed to the organic compound in proportions of 20 and 10%, respectively, being adequate and compatible with the use of CRH in the proportion of up to 30%. Eucalyptus grandis seedlings, after 90 days of cultivation, presented quality to be hardened and dispatched when grown on organic compound substrates with up to 30% CRH, 20% HRH and 10% CPK. v.24 n.2 2018

Fitossociologia e fatores ecológicos condicionantes da vegetação em uma floresta estacional na região central do Rio Grande do Sul, Brasil

Compreender a fitossociologia e fatores ecologicos condicionantes pode subsidiar intervencoes em florestas. Nesse contexto, objetivou-se analisar os componentes arboreo e regenerante e a influencia das variaveis ambientais na distribuicao de especies, em uma Floresta Estacional na regiao central do Rio Grande do Sul. O estrato arboreo foi amostrado em 33 parcelas instaladas sistematicamente, sendo em cada parcela instaladas subunidades para amostrar a regeneracao natural. As principais especies no componente arboreo foram Trichilia clausseni C.DC. e Nectandra megapotamica (Spreng.) Mez e na regeneracao natural foram Trichilia elegans A. Juss. e Cupania vernalis Cambess. Relevo, solo e dossel condicionaram especies do estrato arboreo e regeneracao natural. O estadio regenerante das especies foi condicionado por variaveis distintas das relacionadas ao estadio adulto. Contudo, ocorreram casos em que apenas uma variavel, por exemplo, a relacao entre o teor de materia orgânica no solo e Trichilia elegans , influenciou tanto o estadio adulto quanto o regenerante.

Regímenes de riego y dosis de polímero hidroretenedor sobre características morfológicas y fisiológicas de plantas de Cordia trichotoma

The objective of this research was to define which irrigation regime, whether or not combined with water retaining polymer doses added to the substrate, is recommended in the production of Cordia trichotoma seedlings. The substrate was used with different dosages of water retaining polymers (0, 1.5, 3.0 and 4.5 g L-1). After emergence the seedlings were subjected to different irrigation regimes (4-4-4, 4-8-8, 4-8-12, 8-8-8, 8-12-12 and 12-12-12 mm day-1, alternating them every 60 days). The experiment was conducted in a completely randomized design in a split plot scheme, where the main plot was formed by the different irrigation regimes and subplots by doses of a hidroretentor polymer. After 180 days of applying the irrigation blades, the following morphological and physiological variables were obtained. Seedlings are intolerant to water stress after 180 days under blade 4 or 12 mm constant irrigation. The permanent use of the 4 mm day-1 blade is possible, since associated with an addition of approximately 2.4 g L-1 dose of a water retaining polymer to the substrate. A suitable growth of seedlings was obtained with blades of 4-8-8 mm day-1, alternating every 60 days with the possibility of using a smaller blade at the start of growth, thereby reducing water consumption.

Aspectos eco-fisiológicos limitantes da regeneração natural

Natural regeneration comprises the initial stages of establishment and development, and is considered a slow and unpredictable process, due to the complex interaction between the successful establishment of seedlings and different environmental factors. Thus, the aim of this study was show a review addressing eco-physiological factors influencing the natural regeneration of forests as reserves of seed, production and seed dispersal, germination and dormancy, temperature, and water availability and light. Knowledge of the effect of these factors and their interactions with the community are essential to forest management, regarding its management and revegetation of disturbed areas. Thus, simulations of regeneration constitute naturally a very useful tool.