scholarly journals Quality and growth of mangaba (Hancornia speciosa) seedlings according to the substrate and shading

2020 ◽  
pp. 531-536
Author(s):  
Isabela Machado de Oliveira Lima ◽  
Josiane Souza Salles ◽  
Edilson Costa ◽  
Alexandre Henrique Freitas de Lima ◽  
Flávio Ferreira da Silva Binotti ◽  
...  
Keyword(s):  
Quality Index ◽  
Dry Mass ◽  
Growth Environment ◽  
Full Sunlight ◽  
Fine Grain ◽  
Randomized Experimental Design ◽  
Number Of Leaves ◽  
Hancornia Speciosa ◽  
Neck Diameter ◽  
Dickson Quality Index

The use of suitable substrates and growing environments are essential to produce high quality seedlings. This work evaluated shading levels and different substrates to produce mangaba seedlings. Growth environments with 0, 18, 35, and 50% shading were evaluated. In these environments, four substrates (S) were obtained from the combinations of soil (So), cattle manure (M), commercial substrate (CS), sand (Sa) and fine grain vermiculite (V), where: S1 = 0% So, 45% M, 20% CS, 20% Sa, 15% V, S2 = 15% So, 30% M, 20% CS, 20% Sa, 15% V, S3 = 30% So, 15% M, 20% CS, 20% Sa, 15% V, and S4 = 45% So, 0% M, 20% CS, 20% Sa, 15% V. For each growth environment, a completely randomized experimental design with five replications of five seedlings was adopted. The substrates S2 and S3 originated the best seedlings with the largest number of leaves, the largest dry mass of shoot, root, and total, and the highest Dickson quality index. The highest plants were obtained in the substrate S2. In the full sunlight environment, the conducted plants in S2 presented larger neck diameter. The environments with 0 and 18% of shading provided plants with larger leaves, larger aerial and total phytomass, and Dickson quality index. The environment in full sunlight promoted plants with a larger diameter. Therefore, it is recommended to produce seedlings on substrates S2 and S3 and in environments of 0 and 18% of shading.

scholarly journals Agricultural residues as substrates in the production of formosa papaya, okra and zucchini seedlings

2020 ◽  
Vol 36 (6) ◽  
Author(s):  
Paola Lo Monaco ◽  
Larissa Ionara Silva Paula ◽  
Paola Honorato Salla ◽  
Ismail Ramalho Haddade ◽  
Gustavo Haddad Souza Vieira ◽  
...  
Keyword(s):  
Root Length ◽  
Quality Index ◽  
Dry Mass ◽  
High Potential ◽  
Grape Pomace ◽  
Alternative Substrate ◽  
Randomized Design ◽  
Number Of Leaves ◽  
Organic Compost ◽  
Dickson Quality Index

Using residues generated in agriculture to produce seedlingsis an economically interesting alternative, besides being a way to reduce the environmental impacts caused by their inadequate disposal. This study aimed to evaluate the potential of using coffee chaff (CC) and organic compost (OC) as substrate components for the production of Formosa papaya seedlings and the potential of grape pomace (GP), a vitiviniculture residue, in the composition of substrates for the production of okra and zucchini seedlings. We carried out two trials in a completely randomized design (CRD): the first had seven treatments and six replicates: T0: 100% commercial substrate Bioplant® (CS); from T1 to T6: increasing proportions of CC and decreasing of CC: 10/90; 20/80; 30/70; 40/60; 50/50 e 60/40%. The second had six treatments and six replicates, with increasing proportions of GP and decreasing proportions of CS: 0/100; 10/90; 20/80; 30/70; 40/60 and 50/50%.In the first trial we evaluated the number of leaves, root length, seedling height, stem diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI) at 59 days after sowing.The second trialwas performed at 12 and 18 DAS and we analyzed the number of leaves, plant height, root length, collar diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI). Variables that met the assumptions of normality and homoscedasticity were subjected to Dunnett’s test. The substrate composed of coffee chaff and organic compost has a high potential to be used as an alternative substrate due to promote better quality of papaya seedlings compared to the commercial substrate. Alternative substrate containing 60% coffee chaff and 40% organic compost is recommended for the production of  Formosa papaya seedlings in tubes. The grape pomace (GP) has a high potential to be used as component in substrate for the production of okra and zucchini seedlings compared to the commercial substrate (CS) only. Alternative substrate composed of 50% GP and 50% CS is recommended for the production of zucchini seedlings, while substrate composed of 10% GP and 90% CS is recommended for the production of okra seedlings.

scholarly journals Light intensity and type of container on producing Cassia grandis L. f. seedlings

2015 ◽  
Vol 19 (10) ◽  
pp. 939-945
Author(s):  
Caio C. P. Leal ◽  
Salvador B. Torres ◽  
Rômulo M. O. de Freitas ◽  
Narjara W. Nogueira ◽  
Raul M. de Farias
Keyword(s):  
Quality Index ◽  
Dry Mass ◽  
Wood Powder ◽  
Probability Level ◽  
Full Sunlight ◽  
Tukey Test ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Clay Pots ◽  
Dickson Quality Index

ABSTRACTThis study aimed to determine the effects of the luminosity and type of container on producing Cassia grandis seedlings. Thus, in a substrate composed by topsoil + wood powder (1:1) the seedlings were grown into plastic tubets containing 0.3 dm3 of such substrate, or into plastic pots containing 1.0 dm3 of the same substrate, and subjected to 50 and 25% shading or full sunlight. The assessments were performed every two weeks by measuring plant height and stem diameter, during eight weeks period. At the end of this period, the leaf area, dry mass of shoots and roots, the ratio between height of plant/diameter of stem, and the Dickson quality index were also assessed. The experiment was carried out in a completely randomized design with treatments arranged in a 3 x 2 factorial [3 luminosity levels (50, 25% shading and full sunlight) x 2 types of containers (plastic tubets and clay pots)] with four replicates of 10 seedlings each. Means were compared by Tukey test at 0.05 probability level and adjustments for the non-linear regression polynomial curves for the assessed characteristics were computed in function of time. Shadings of 25 and 50% were the best alternatives to luminosity; and the tubets were the most suitable containers for production of Cassia grandis seedlings.

scholarly journals PRODUCTION OF STAR FRUIT ROOTSTOCKS FERTILIZED WITH DIFFERENT BORON DOSES

2017 ◽  
Vol 92 (3) ◽  
pp. 221
Author(s):  
Clariana Xavier ◽  
William Natale
Keyword(s):  
Experimental Design ◽  
Quality Index ◽  
Block Design ◽  
Dry Mass ◽  
Tropical Fruits ◽  
Nutritional Properties ◽  
Star Fruit ◽  
Randomized Block Design ◽  
Number Of Leaves ◽  
Dickson Quality Index

Among the tropical fruits, star fruit stands out due to its flavor and nutritional properties. Nevertheless, the information on fertilization and nutrition of this fruit is still scarce. For this reason, this study aimed to assess the effect of different boron doses on star fruit rootstock growth. The experimental design was randomized block design, consisting of five treatments of boron application (0, 1, 2, 3, and 4 mg dm−3) and four replications. Star fruit rootstock did not respond to boron doses applied to the substrate and hence it did not influence the parameters stem diameter, plant height, the number of leaves, dry mass of shoot, dry mass of roots, total dry mass, and Dickson quality index (DQI). A boron dose up to 4 mg dm−3 (800% of the recommended boron dose of 0.5 mg dm−3) did not produce symptoms of visual toxicity in the plant.

scholarly journals Organic substrates and formononetin for Leucaena leucocephala saplings

2019 ◽  
Vol 13 ◽  
pp. 24
Author(s):  
Djalma Silva Pereira ◽  
Gilca Dos Santos Veloso ◽  
Rafaela Simão Abrahão Nóbrega ◽  
Altemar Dos Santos Dias ◽  
Audrey Ferreira Barbosa ◽  
...  
Keyword(s):  
Organic Compound ◽  
Leucaena Leucocephala ◽  
Quality Index ◽  
Dry Mass ◽  
Initial Growth ◽  
Organic Substrates ◽  
Height Ratio ◽  
Shoot Height ◽  
Randomized Experimental Design ◽  
Dickson Quality Index

To obtain quality saplings it is necessary to consider the requirements the plants have for a balanced nutriente intake. These can be made available from organic waste which, in many cases, is simple to acquire and can be recycled easily. Consequently, the current study evaluated the potential of organic substrates and formononetin for the production of Leucaena leucocephala seedlings. Experiments were carried out in a greenhouse, using a fully randomized experimental design, in a factorial arrangement (5 x 2), with five soil proportions: organic compound (100: 0, 80:20, 60:40, 40:60, 20 : 80) and two doses (0 and 1.0 mg per seed) of the isoflavonoid formononetine (7-hydroxy-4’-methoxy-isoflavone, Myconate®). After 60 days of sowing, shoot height, stem diameter, shoot height ratio, shoot diameter, number of nodules, aerial dry mass (ADM), root dry mass (RDM), total dry matter and Dickson Quality Index (DQI) of the Leucaena leucocephala seedlings were evaluated. Formononetin positively influenced dry root and total dry mass production, and the Dickson Quality Index of Leucaena leucocephala seedlings. A substrate with 46% soil and 54% organic compound gave the highest seedling DQI, this thereforee being the recommended proportions for this specieds during the initial growth phase.

scholarly journals Resposta de Handroanthus heptaphyllus Mattos em diferentes volumes de substrato e adubação de base.

FLORESTA ◽  
2020 ◽  
Vol 50 (4) ◽  
pp. 1770
Author(s):  
Thaise Da Silva TONETTO ◽  
Maristela Machado Araujo ◽  
Álvaro Luís Pasquetti Berghetti ◽  
Márcio Carlos Navroski
Keyword(s):  
Controlled Release ◽  
Quality Index ◽  
Lower Cost ◽  
Dry Mass ◽  
High Dose ◽  
Native Forest ◽  
Forest Species ◽  
Definition Of ◽  
Appropriate Practices ◽  
Dickson Quality Index

Handroanthus heptaphyllus (Martius) Mattos response in different volumes of substrate and base fertilization. The native forest species require the adoption of appropriate practices in the nursery, such as the definition of the container volume and base fertilizer, to develop seedlings at lower cost. Thus, this study aimed to verify the performance of Handroanthus heptaphyllus seedlings grown in nurseries in different sizes of containers and different dosage of controlled release fertilizer (CRF). There was interaction between the volume of container and the fertilization for the height (H), stem diameter (SD), and H/SD relation. The shoot dry mass variable (SDM), root dry mass (RDM), total dry mass (TDM), SDM/RDM relation, Dickson quality index (DCI) and leaf area (LA) were influenced only by the base fertilizer. The highest values for these variables were, respectively, 15.68 cm; 6.55 mm, 2.58 cm mm-1; 2.05 g; 2.03 g; 3.84 g; 1.46; 1.15 and 246.97 cm². The H. heptaphyllus species is nutritionally demanding, positively responding to the high dose of CRF. Seedlings of H. heptaphyllus produced in tubes of 180 cm³ with 7.0 g L-1 of CRF present adequate growth.

scholarly journals Morphological divergence of seedlings Calophyllum brasiliense cambes collected in São Paulo and Tocantins

2021 ◽  
Author(s):  
Ildon Rodrigues Nascimento ◽  
Cândida Pereira da Silva ◽  
Irais Dolores Pascual-Reyes ◽  
Aline Torquato Tavares ◽  
Edilson Nonato da Silva ◽  
...  
Keyword(s):  
Root Length ◽  
Quality Index ◽  
Morphological Characteristics ◽  
Dry Mass ◽  
Sao Paulo ◽  
The State ◽  
Morphological Divergence ◽  
São Paulo ◽  
Calophyllum Brasiliense ◽  
Number Of Leaves

Objective: The objective was to quantify the morphological diversity of Calophyllum brasiliense Cambes from four municipalities of the State of Tocantins employing morphological characteristics, to strengthen information on conservation and future breeding of the species. Methodology: Seeds were collected from four municipalities in the State of Tocantins and one in the State of São Paulo. The following were evaluated: plant height, stem diameter, root length, number of leaves, leaf area, root dry mass, shoot dry mass, total dry mass, and Dickson´s quality index. The data were subjected to univariate analysis of variance, Tocher grouping method, and UPGMA, obtaining a dendrogram through the generalized Mahalanobis distance. Results: The results showed a statistical difference of 1 and 5% probability. Dueré stood out in stem diameter(5.52 mm), Sandolandia in height (34.84 cm) and root length (42.13 cm). Formoso stood out in the number of leaves (34 leaves). Lagoa da Confusão in leaf area (856.28 cm 2 ) and São Paulo in root dry mass (16.20 g), shoot dry mass (12.38 g), total dry mass (16.20 g), and Dickson´s quality index (1.57). Implications: Variations in morphological characteristics can be used as a tool for genetic studies of guanandi progeny accordingto their similarity and/or differences. Conclusions: The morphological divergence evidenced that among the five studied areas it is possible to direct the collection of seeds to subsidize conservation strategies and future breeding of the species.

scholarly journals Matrix management interfers in yield and quality of cocoa seedlings

2018 ◽  
Vol 40 (3) ◽  
Author(s):  
Rafaela Alves Pereira ◽  
Gedeon Almeida Gomes Júnior ◽  
Eliandro Malta Rodrigues ◽  
George Andrade Sodré ◽  
Célio Kersul do Sacramento
Keyword(s):  
Quality Index ◽  
Quality Evaluation ◽  
Pearson Correlation ◽  
Dry Mass ◽  
Experimental Unit ◽  
Plant Management ◽  
Yield And Quality ◽  
Cocoa Seedlings ◽  
Dickson Quality Index

Abstract The influence of two managements on yield and quality of plagiotropic mini-cuttings of four cacao clones was evaluated. The design was completely randomized in a 4 x 2 factorial scheme with 4 clones x 2 mother plant management (apical pruning and bending), with 10 replicates and one plant as experimental unit. Seedlings used were propagated by rooting of semi-woody cuttings of plagiotropic branches and at seven months of age, two seedlings of each clone were transplanted to 12 L pots filled with organomineral substrate. After transplantation, the apex of one of the plants was cut based on the count of the first six leaves from the apex. For bending, stems were folded and horizontally fixed. The first collection of mini-cuttings was performed 30 days after transplantation and the others during the following seven months. The yield of mini-cuttings was estimated during collections and part was used for rooting and quality evaluation of seedlings. After 90 days, 10 mini-cuttings of each clone were evaluated for quality using the Dickson quality index (DQI). Another 10 rooted mini-cuttings were transplanted to 1.5 L polyethylene bags and kept in greenhouse for another 120 days until final quality evaluation at 210 days. Data were submitted to analysis of variance and Tukey test at 5% probability. Shapiro-Wilk normality test and Pearson correlation analysis were performed. bending was more efficient in the average production of mini-cuttings especially for BN 34 clone. The Dickson quality index was correlated with root dry mass, at both 90 and 210 days, and the bending technique was responsible for the best DQI. Variable height was not adequate to estimate the quality of cocoa seedlings.

Influência da Casca de Arroz Carbonizada no Desenvolvimento de Mudas de Enterolobium contortisiliquum (VELL.) Morong

UNICIÊNCIAS ◽  
2018 ◽  
Vol 22 (2) ◽  
pp. 76
Author(s):  
Vinícius Moreira Vaz ◽  
Douglas Santos Gonçalves ◽  
Priscila Bezerra De Souza
Keyword(s):  
Rice Husk ◽  
Quality Index ◽  
Dry Mass ◽  
Native Forest ◽  
Seedling Production ◽  
University Campus ◽  
Forest Nursery ◽  
Forest Species ◽  
Shoot Height ◽  
Dickson Quality Index

Entre as espécies florestais nativas indicadas para a recuperação de áreas degradas está o Enterolobium contortisiliquum (Vell.) Morong, pouco se sabe sobre os processos germinativos e de produção de mudas desta espécie. Diante disso, o presente estudo teve como objetivo avaliar a influência da casca de arroz carbonizada no desenvolvimento de mudas de Enterolobium contortisiliquum. O experimento foi conduzido no Viveiro Florestal da Universidade Federal do Tocantins, campus Universitário de Gurupi – TO, em que foram instalados cinco tratamentos e 20 repetições, com adição de Casca de Arroz Carbonizada (CAC) no substrato comercial Bioflora® (SCB), nas proporções de (T1) 0% CAC + 100% SCB, (T2) 25% CAC + 75% SCB, (T3) 50% CAC + 50% SCB, (T4) 75% CAC + 25% SCB e (T5) 100% CAC. Aos 20, 40 e 60 dias, após a semeadura, foram avaliados os parâmetros altura da parte aérea e diâmetro do coleto. Ao final de 60 dias foram obtidos os parâmetros: peso da massa seca da raiz, peso da massa seca da parte aérea, peso da massa seca total e índice de qualidade de Dickson. O delineamento experimental utilizado foi o inteiramente casualizado (DIC), as médias dos tratamentos foram comparadas através do Software Assistat 7.7 pelo teste Scott e Knott ao nível de 5% de probabilidade. O uso de casca de arroz carbonizada (CAC) influenciou no desenvolvimento de mudas de Enterolobium contortisiliquum (Vell.) Morong. Palavras-chave: Substratos Alternativos. Tamboril. Viveiro Florestal AbstractAmong the native forest species indicated for the recovery of degraded areas is Enterolobium contortisiliquum (Vell.) Morong, little is known about the germination processes and seedling production of this species. Therefore, the present study aimed to evaluate the influence of carbonized rice husk on the development of Enterolobium contortisiliquum seedlings. The experiment was conducted in the Forest Nursery of the Federal University of Tocantins, University campus of Gurupi - TO, five treatments and 20 replicates were installed, with the addition of Carbonized Rice Peel (CAC) in the commercial substratum Bioflora ® (SCB), in proportions (T1) 0% CAC + 100% SCB, (T2) 25% CAC + 75% SCB, (T3) 50% CAC + 50% SCB, (T4) 75% CAC + 25% SCB and (T5) 100% CAC . At 20, 40 and 60 days after sowing, the parameters of shoot height and shoot diameter were evaluated. At the end of 60 days, the following parameters were obtained: root dry mass weight, shoot dry mass weight, total dry mass weight and Dickson quality index. The used experimental design  was completely randomized (DIC), the means of the treatments were compared using Software Assistat 7.7 by the Scott and Knott test at the 5% probability level. The use of carbonized rice husk (CAC) influenced the development of Enterolobium contortisiliquum (Vell.) Morong seedlings. Keywords: Alternative Substrates. Monkfish. Forest Nursery

scholarly journals SELETIVIDADE DE MISTURAS DE HERBICIDAS E INSETICIDAS EM TANQUE APLICADAS EM HÍBRIDOS DE MILHO

2018 ◽  
Vol 17 (2) ◽  
pp. 287
Author(s):  
CLEBER DANIEL DE GOES MACIEL ◽  
ANDRÉ AUGUSTO PAZINATO DA SILVA ◽  
ENELISE OSCO HELVIG ◽  
ANTÔNIO MENDES DE OLIVEIRA NETO ◽  
NAIARA GUERRA ◽  
...  
Keyword(s):  
Zea Mays ◽  
Dry Mass ◽  
Development Stage ◽  
Initial Growth ◽  
Phenological Stages ◽  
Maize Hybrids ◽  
Randomized Experimental Design ◽  
Number Of Leaves ◽  
Chemical Groups ◽  
Chlorpyrifos Ethyl

 RESUMO - A associação de herbicidas e inseticidas é uma prática comum entre os agricultores, entretanto, muitas vezes pode provocar injúrias à cultura do milho. O trabalho teve como objetivo avaliar a seletividade de herbicidas em mistura em tanque com inseticidas de diferentes grupos químicos, no crescimento inicial de hibridos de milho. Dois experimentos foram conduzidos separadamente em estufa plástica com dois híbridos de milho (30F35 e 2B-710), utilizando como unidades experimentais vasos com duas plantas nos estádios fenológicos V3 e V6. O delineamento experimental foi o inteiramente casualizado, com cinco repetições. Foram avaliados 31 tratamentos, representados pela aplicação de seis herbicidas (atrazine, nicosulfuron, foramsulfuron + iodosulfuron, mesotrione, carfentrazone e 2,4-D, nas doses de 2000; 37,5; 36+2,4; 144; 10 e 1000 g ha-1, respectivamente) isolados e em mistura com quatro inseticidas (permethrin, methomyl, chlorpyrifos ethyl e novarulon, nas doses de 26,9; 64,5; 240 e 15 g ha-1, respectivamente) e uma testemunha sem aplicação. Avaliou-se a intoxicação das plantas aos 7 e 14 dias após a aplicação (DAA), o teor de clorofila das folhas, número médio de folhas por planta, massa seca da parte aérea e das raízes aos 14 DAA. Os resultados foram variáveis em função do híbrido e estádio fenológico na aplicação, sendo as misturas menos prejudiciais ao milho quando aplicadas em V3. Os tratamentos com atrazine foram os que menos afetaram o crescimento inicial dos híbridos. As misturas nicosulfuron + chlorpyrifos ethyl, mesotrione + chlorpyrifos ethyl e 2,4-D + chlorpyrifos ethyl foram as que mais prejudicaram o híbrido 30F35. Por outro lado, a mistura carfentrazone + chlorpyrifos ethyl foi a que mais afetou o crescimento inicial do híbrido 2B-710.Palavras-chave: fitointoxicação, antagonismo, estádio de desenvolvimento, Zea mays. SELECTIVITY OF HERBICIDES AND INSECTICIDES TANK MIXTURES APPLIED IN MAIZE HYBRIDS  ABSTRACT - The association of herbicides and insecticides despite often cause damage to the corn crop is a common practice among farmers. This study aimed to evaluate the initial selectivity of herbicides in tank mixture with insecticides from different chemical groups in maize. Two experiments were carried out in plastic greenhouse, using as experimental units pots with two maize hybrids (30F35 and 2B-710) in V3 and V6 phenological stages. A completely randomized experimental design was used, with five replications. Thirty-one treatments were represented by applying six herbicides (atrazine, nicosulfuron, foramsulfuron+iodosulfuron, mesotrione, carfentrazone and 2.4- D) isolated and in combination with the four insecticides (permethrin, methomyl, chlorpyrifos ethyl and novarulon) and a check without application. The phytointoxication was evaluated at 7 and 14 days after application (DAA), the chlorophyll content in leaves, total number of leaves, dry mass of the aerial part and roots at 14 DAA. The results were dependent of hybrid and corn stage in the application, and mixtures were less harmful when applied in V3 stage. The treatments with atrazine affected less the initial growth of the two hybrids. The mixtures of nicosulfuron+chlorpyrifos ethyl, mesotrione+chlorpyrifos ethyl and 2.4-D + chlorpyrifos ethyl were the most prejudicial to the hybrid 30F35. In addition, the carfentrazone + chlorpyrifos ethyl mixture was the most harmful to the initial growth of the hybrid 2B-710.Keywords: phytointoxication, antagonism, development stage, Zea mays.

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

FLORESTA ◽  
2014 ◽  
Vol 44 (4) ◽  
pp. 607
Author(s):  
Rudinei De Marco ◽  
Bruno Conte ◽  
Edison Rogério Perrando ◽  
Fabiano De Oliveira Fortes ◽  
Lucindo Somavilla ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Low Temperatures ◽  
Quality Index ◽  
Aerial Part ◽  
Single Layer ◽  
Dry Mass ◽  
Plastic Bags ◽  
Toona Ciliata ◽  
Santa Maria ◽  
Dickson Quality Index

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.

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