EFEITO DE TELAS DE SOMBREAMENTO NO CRESCIMENTO E PROTEÇÃO DE MUDAS DE Toona ciliata SOB BAIXAS TEMPERATURAS

Abstract

O objetivo deste trabalho foi avaliar a influência de diferentes camadas de telas de sombreamento no crescimento e na proteção de mudas de Toona ciliata em períodos de suscetibilidade a geadas. O estudo foi conduzido na Universidade Federal de Santa Maria, Campus Frederico Westphalen, RS. Para a realização do experimento, mudas de Toona ciliata foram mantidas em sacos plásticos com capacidade de três litros e submetidas a quatro tratamentos: mudas sem proteção e mudas sob proteção com camada simples, dupla e tripla de sombreamento. O delineamento foi o inteiramente casualizado, com quatro repetições de oito mudas por repetição. Foi avaliado o número de mudas com folhas apicais necrosadas, a altura da parte aérea, o diâmetro do colo e a massa seca radicular, aérea e total. Por meio dessas variáveis, foi possível determinar o Índice de Produtividade, o Índice de Qualidade de Dickson e as relações altura/diâmetro e altura/massa seca da parte aérea. A utilização de telas de sombreamento mostrou-se eficiente para a proteção das mudas contra o efeito adverso da geada. O uso de uma camada simples de sombreamento resultou em maior proteção e consequentemente forneceu as melhores características dendrométricas em relação às demais intensidades de sombreamento.Palavras-chave: Tela de proteção; tolerância à geada; cedro australiano. AbstractEffect of shading screens on growth and protection of Toona ciliata seedlings under low temperatures. This research aimed to evaluate the influence of different shading screens layers on the growth and protection of Toona ciliata seedlings in periods of frost susceptibility. The research was conducted on the Santa Maria Federal University, Frederico Westphalen Campus, RS. For the experiment, Toona ciliata seedlings maintained in plastic bags with three liters of capacity each were submitted to four treatments: unprotected seedlings, seedlings under protection with a single shading layer, double and triple. The experimental design was the completely randomized, with four repetitions of eight seedlings each. It was evaluated the number of seedlings with necrosed apical leaves, the aerial part height, the lap diameter and the dry mass of root, aerial and total. By such variables, it was possible to determine the Produtivity Index, the Dickson Quality Index and the relations height/diameter and height/dry mass of aerial part. The use of shading screens showed up efficient to protect the seedlings against the adverse effect of frost. The use of a single layer of shading resulted in a greater protection and consequently provided the best dendrometric characteristics, compared to the others levels of shading.Keywords: Screen protection; tolerance to frost; Australian cedar.

Container volume and shading in Parkia multijuga Benth. propagation in nursery

“…The shading of the seedlings also influenced the relations between shoo theight and dry mass (H/DSM), with values increasing proportionally with greater light restriction, corroborating with the results obtained by De Marco et al (2014) in Toonaciliata M. Roem. var.…”

Effect of shading on Dimorphandra gardneriana Tul. seedling production

“…For seedlings of Toona ciliata M. Roem var. australis produced without shading, the lowest height/diameter was not synonymous of quality, because the seedlings grown in full sun were necrotic, which had negative influence on the increase in height (MARCO et al, 2014).…”

“…For Toona ciliata var. australis, seedlings the best DQI was achieved when a simple shading layer was used (MARCO et al, 2014).…”

“…The shoot length data did not fit the regression models, but there was a growing trend at the highest level of shading ( Figure 2). According to Marco et al (2014) shaded plants tend to have greater height owing to light deficiency and therefore blanching occurs. The percentage of D. gardneriana seedling survival was not influenced by levels of shading used in nursery, with high percentages in all treatments.…”

Alteración De Los Recursos Naturales Y Su Efecto en El Paisaje en Zonas De Interés Turístico Al Sur De Chile

“…australis sob 50% de sombra (MARCO et al, 2014). O maior crescimento em altura em plantas sob sombreamento tem sido considerado um mecanismo de escape à baixa luminosidade, pois ao aumentar a altura, a planta tende a superar a vegetação próxima e expõe sua superfície fotossintetizante à luz (QUEIROZ; FIRMINO, 2014).…”