Desenvolvimento de Mudas de Nim Indiano sob Diferentes Níveis de Sombreamento

Abstract

RESUMOEste estudo teve como objetivo avaliar o efeito de níveis de sombreamento na produção de mudas de nim indiano (Azadirachta indica), visando a obtenção de mudas com maior padrão de qualidade. Foram adotados quatro tratamentos (pleno sol, 30%, 50% e 70% de sombreamento), dispostos em delineamento inteiramente casualizado, com seis repetições. Os parâmetros avaliados, aos 100 dias, foram: altura da parte aérea, diâmetro do coleto, relação altura/diâmetro, massa fresca e seca da parte aérea, raízes e total, número de folhas e índice de qualidade de Dickson. Os dados foram submetidos à análise de variância, sendo as médias comparadas pelo teste de Duncan a 5% de significância. Mudas produzidas a pleno sol apresentaram maior padrão de qualidade, sendo observados valores mais adequados para os parâmetros diâmetro do coleto, relação altura/diâmetro, massa fresca e seca das raízes, número de folhas e índice de qualidade de Dickson.Palavras-chave: viveiros florestais, luminosidade, parâmetros morfológicos, Azadirachta indica. Development of Indian Neem Seedlings under Different Levels of Shading ABSTRACTThe purpose of this study was to evaluate the effect of levels of shading on the seedling production of Indian neem (Azadirachta indica), aiming to obtain seedlings with higher quality standard. Four treatments were adopted (full sun; 30%, 50% and 70% of shading), arranged in a completely randomized design, with six replications. The following parameters were evaluated after 100 days: height of the aerial part; root-collar diameter; height/diameter ratio; fresh and dry mass of shoots, roots and total; number of leaves; and Dickson quality index. The data were subjected to analysis of variance and the averages were compared by the Duncan test at 5% significance level. Seedlings produced under full sun showed higher standard of quality, with more suitable values observed for the following parameters: root-collar diameter, height/diameter ratio, fresh and dry mass of roots, number of leaves, and Dickson quality index.

Effect of shading on Dimorphandra gardneriana Tul. seedling production

“…were influenced by different shadings, with the highest growth (height and diameter) occurring under 30% shading achieved using a reflective screen of 50% (Santos et al, 2014). In the study by Azevedo et al (2015), using different shading levels (0%, 30%, 50%, and 70%) in the production of seedlings of Azadirachta indica A. Juss, the highest height and diameter values, and lowest height/diameter ratios were obtained from seedlings produced full sun.…”

“…The different levels of shading (0%, 30%, 50%, and 70%) influenced the quality of Azadirachta indica seedlings, with the highest DQI values obtained from seedlings grown in full sun (AZEVEDO et al, 2015). The DQI was also considered by Dutra et al (2015) as an excellent variable to indicate the standard of seedling quality of Copaifera langsdorffii Desf., since the seedlings with the highest rates had maximum total dry mass and shoot values.…”

“…Among the environmental factors that directly affects forest seedling production is the light requirement of the species, including light intensity, quality, and duration, since the availability of radiation is an important factor in energy flow in biological systems, and depending on the ability to capture and use light, the responses of plants are different and crucial for their survival, growth, and adaptation to different environments (SARAIVA et al, 2014;AZEVEDO et al, 2015). With this, Dutra et al (2015) emphasized that changes of growth efficiency can be associated with the ability of plants to adapt to the environmental light conditions.…”

“…S. F. Blake can be produced in shadings of 30%, 50%, and 70%, obtaining quality seedlings with stem height and diameters compatible for transplanting, but its exposure to shade should not exceed 45 days, since from that period the plants begin the process of blanching (CARON et al, 2010). However, Azevedo et al (2015) found that Azadirachta indica A. Juss seedlings produced in full sun had a better quality standard based on the morphological characteristics, such as stem diameter, height/diameter, fresh and dry mass of roots, number of leaves, and the Dickson index quality.…”

Shading improves initial growth and quality of Parkia multijuga Benth. seedlings

“…These results observed for the shoot height variable are similar to those obtained by Queiroz and Firmino (2014), who observed higher heights in the Dipteryx alata plants grown under shading, when compared to full sunlight conditions, where there were no significant differences between the shading levels evaluated. For Dalbergia nigra (Pacheco et al, 2013) and Azadirachta indica (Azevedo et al, 2015), bigger seedlings were also observed, when they were exposed to increasing shading levels. The collar diameter of the seedlings under full sunlight did not differ among seedlings under 50% shading; however, this variable differed for the seedlings under 70% shading, which presented larger diameter.…”