ABSTRACT: The characterization of substrate properties supports the correct choice of components and directs management decisions in container cultivation. There are several systems of analysis, however, the routine procedures to determine the water retention curve (WRC) are time consuming and inaccurate. This study proposed a reproducible, less time-consuming, and easy to perform method for physical characterization of substrates. We used Sphagnum peat, coconut powder, carbonized rice husk, expanded vermiculite, and expanded clay in isolation. The WRC was obtained at tensions 0, 10, 50, and 100 hPa using the method of Büchner funnel, the European standard (CEN-EN13041), and by the centrifugation method of samples. In centrifugation, tensions were simulated by combining the angular velocity, sample height, and radius measured from the sample outermost point to the central point of the centrifuge. Three rotations were applied (230; 520 and 730 rpm), testing the centrifugation time for each tension and then the volumetric water content was compared between the methods. The results showed a positive correlation (p < 0.001) between the centrifugation and standard methods, considering that the centrifugation time required for moisture stabilization varied according to the material analyzed and the tension applied. However, the time required to obtain a report was reduced by half. Sample centrifugation is a promising method, ensuring that the tensile force actually acts on the entire sample to determine the water retention curve of the substrate also reducing the duration of the analyses.

Abstract This study evaluated the effect of disinfestation methods and different storage environments on the germination of seeds of Limonium brasiliense (Boiss.) Kuntze. Seeds were disinfested using ethanol followed by sodium hypochlorite; water under agitation; and no disinfestation from two origins. Longevity was tested by storing the seeds in a cold chamber, dry chamber, and at ambient laboratory temperature. Beginning of germination (BG), percentage (%G), and mean germination time (MGT) and mean germination speed index (MGSI) were evaluated. Data were submitted to an analysis of variance, comparison of mean values and a polynomial regression analysis (p<0.05). In the disinfestation, there was significant difference in %G and MGT only between origins. For longevity, IG and MGSI had a positive and negative linear behavior, respectively, while %G had a quadratic behavior. L. brasiliense seeds disinfestation does not affect germination. Dry chamber was the most suitable storage environment.

Resumo Considerando-se que os substratos apresentam constituições físico-químicas diversas e que a liberação de íons do substrato, ou a adição de fertilizantes, eleva a condutividade elétrica da solução, este trabalho teve como objetivo avaliar a retenção de água em substratos com hidrogel com presença e ausência de adubação. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 4 x 3 x 2, com quatro repetições. Os fatores constituíram de quatro tipos de substratos (casca de pinus compostada, pó-de-coco (fibra do mesocarpo triturada), turfa de Sphagnum e substrato comercial (à base de turfa de Sphagnum, vermiculita expandida, casca de arroz torrefada, calcário dolomítico e gesso agrícola), três formas de aplicação do produto hidrogel (sem aplicação, com aplicação sem pré-hidratação e com aplicação após hidratação) e duas formas de aplicação de fertilização de base (na presença e ausência). O hidrogel utilizado foi um copolímero de poliacrilato de potássio (K2S2O8). Os resultados apontam que a adição de hidrogel promove melhorias na capacidade de retenção de água dos substratos, contudo, é influenciada pela sua composição e pela presença de fertilizantes químicos. Quanto maior a Condutividade Elétrica (CE) do substrato, menor é o potencial de hidratação do hidrogel. A forma de aplicação do hidrogel, se seco ou pré-hidratado, não influencia a capacidade de retenção de água pelos substratos. O hidrogel aplicado no substrato, uma vez desidratado, mantém sua capacidade de reidratação.

Abstract Considering that the substrates have different physical and chemical constitutions and that the release of ions from the substrate or the addition of fertilizers increases the electrical conductivity of the solution, the objective of this work was to evaluate the water retention in substrates with hydrogel, without and with fertilization. The experimental design used was a completely randomized, in a 4 x 3 x 2 factorial scheme, with four replications. The factors consisted of four substrates (composted pine bark, coconut powder (crushed mesocarp fiber), Sphagnum peat and commercial substrate (based on Sphagnum peat, expanded vermiculite, roasted rice husk, dolomitic limestone and plaster), three forms of application of the hydrogel product (without application, with application without pre-hydration and with application after hydration) and two ways of applying the basic fertilization (present and absent) .The hydrogel used was a potassium polyacrylate copolymer (K2S2O8). The results show that the addition of hydrogel promotes improvements in the water retention capacity of the substrates However, it is influenced by its composition and by the presence of chemical fertilizers. The higher the EC of the substrate, the lower the hydration potential of the hydrogel. The hydrogel application method, whether dry or pre-hydrated, does not influence the water retention capacity by the substrates. The hydrogel applied to the substrate once dehydrated, maintains its ability to rehydrate.

SUMMARY: Butia lallemantii is endemic from sandy soils in the state of Rio Grande do Sul (RS). Sandblasted soils stand out for fragile characteristics of low fertility, water availability and intense sand displacement. However, studies on planting techniques, use of fertilizers and alternative products that may favor the establishment of plants in these soils are lacking. Therefore, the objective of the study was to evaluate the survival and leaf appearance of the B. lallemantii plants established by the revegetation method in sandy soil, with the increase of mineral fertilizer and hydroretentor polymer, as well as monitoring the movement of sand particles. The plants were collected in Alegrete / RS, classified in stipe diameter and kept in substrate (soil, animal waste and rice husk, 1:1:1) for eight months. In field plantation, the doses of NPK and hydrogel were randomly placed between five graded rules in the soil, for periodic sand displacement readings. Survival, appearance of live leaves and sand displacement were evaluated monthly, with a randomized block design (100 seedlings/block). Results showed higher survival and presence of living leaves in the plants of block one, and average displacement of sand in the spring period. Therefore, plants of larger stipe diameter class show higher potential for survival and larger number of live leaves, in addition, sand displacement mainly happens during spring.

RESUMEN: Butia lallemantii es endémica proveniente de suelos arenosos y arenizados en el estado de Rio Grande do Sul (RS). Los suelos arenizados se destacan por características frágiles de baja fertilidad, disponibilidad de agua y por intenso desplazamiento de arena. Sin embargo, faltan estudios acerca de técnicas de plantación, uso de fertilizantes y productos alternativos que pueden favorecer el establecimiento de plantas en estos suelos. Por lo tanto, el objetivo del estudio fue evaluar la supervivencia y el aspecto foliar de las plantas de B. lallemantii establecidas por el método de revegetación en el suelo arenizado, con el incremento de fertilizante mineral y polímero hidroretentor, así como monitorear el desplazamiento de partículas de arena. Las plantas fueron recolectadas en Alegrete/RS, clasificadas de diámetro del estípite y se mantuvieron en sustrato (suelo, residuos animales y cáscara de arroz, 1:1:1), durante ocho meses. En plantación de campo, las dosis de NPK e hidrogel fueron colocadas aleatoriamente entre cinco reglas graduadas en el suelo, para lecturas periódicas de desplazamiento de arena. La supervivencia, la apariencia de hojas vivas y el desplazamiento de la arena se evaluaron mensualmente, con diseño en bloques al azar (100 plántulas/bloque). Los resultados mostraron una mayor supervivencia y presencia de hojas vivas en las plantas de bloque uno, y un desplazamiento promedio de arena en el período de primavera. Por lo tanto, las plantas de mayor clase de diámetro del estípite pose en alto potencial de supervivencia y de hojas vivas, además, la temporada de primavera mayor desplazamiento de arena.

Resumo Possuidores de elevada biodiversidade, os campos do sul do Brasil vêm sendo ameaçados por diversos fatores, dentre eles, o avanço das fronteiras agrícolas. Áreas de Preservação Permanente (APPs) podem contribuir para a conservação da biota desses ecossistemas mesmo em paisagens cultivadas. O objetivo deste estudo foi descrever a diversidade florística de quatro APPs inseridas em um plantio comercial de Eucalyptus saligna. localizado em Pantano Grande, Rio Grande do Sul, no bioma Pampa. Durante um ano, excursões mensais foram realizadas utilizando o método do Caminhamento para coleta de material botânico. Foram registradas 295 espécies distribuídas em 60 famílias, as mais representativas foram Poaceae (51 spp.), Asteraceae (51 spp.), Cyperaceae (20 spp.), Fabaceae (17 spp.), Rubiaceae (12 spp.), Solanaceae (8 spp.), Malvaceae (8 spp.) e Myrtaceae (6 spp.), correspondendo 56,27% do total. Sobre a origem, 274 espécies são nativas, quatro das quais endêmicas do Brasil e duas ameaçadas de extinção. Em relação ao hábito, as espécies herbáceas foram predominantes (72,2%), seguido por arbustivas (9,58%), subarbustivas (7,87%), arbóreas (6,16%), e trepadeiras (5,13%). Tanto a proporção das famílias, quanto a relação das espécies identificadas corroboram com levantamentos realizados na região, denotando uma elevada riqueza específica. As APPs avaliadas apresentam elevada diversidade florística, mesmo encontrando-se parcialmente isoladas pelos talhões de plantio comercial de eucalipto.

Abstract Grasslands of southern Brazil are composed of high biodiversity and threatened by several factors, such as the advancement of agricultural frontiers. Areas of Permanent Preservation (APP) can contribute to the preservation of these environments. However, studies on their floristic composition are limited, especially about the herbaceous stratum. The objective of this study is to describe the floristic diversity of four Areas of Permanent Preservation inserted in an Eucalyptus saligna. tree crop farm in Pantano Grande, RS, located in the Pampa biome. For a year, monthly collections were performed by walking along all sampled areas. We identified 295 species distributed in 60 families, which Poaceae (51), Asteraceae (51), Cyperaceae (20), Fabaceae (17), Rubiaceae (12), Solanaceae (8), Malvaceae (8) and Myrtaceae (6) were more expressive, corresponding to 56.27% of total. About the origin, 274 species are native, four are endemic and two are endangered. Herbaceous species were predominant (72,2%), followed by shrubs (9,58%), sub-shrubs (7,87%), trees (6,16%) and vines (5,13%). Both the proportion of the families and the relation of species agree with surveys carried out in the region, denoting a high specific richness. The APP evaluated present high floristic diversity, even though they are partially isolated by the eucalyptus forest.

Abstract The propagation of guabijuzeiro (M. pungens) by seed is originating plants with high genetic variability and a long juvenile period. Therefore, the objective was to study the multiplication and rooting in vitro of guabijuzeiro in order to get information to enable the clonal propagation. In the multiplication, apical and nodal segments were used, taken from in vitro plantlets, combined with 6-Benzylaminopurine (BAP), naphthaleneacetic acid (NAA) and gibberellic acid (GA). In the rooting, NAA and IBA (indolebutyric acid) were used. The results showed that in the multiplication there was superiority in media with BAP, while rooting was not satisfactory in media with NAA or IBA. Thus, it is possible to multiply M. pungens in vitro using BAP phytoregulator in the multiplication stage. However, the rooting stage needs more tests to induce the production of roots and facilitate acclimatization of the plants obtained in vitro.

RESUMO A capacidade de hidratação do hidrogel em solução foi avaliada em diferentes níveis de condutividade elétrica (CE), usando nitratos, fosfatos, sulfatos e sais de cálcio, magnésio e potássio. Foram realizados quatro experimentos sequenciais, utilizando-se um copolímero de poliacrilato de potássio. O primeiro ensaio objetivou determinar a menor dose de hidrogel, na qual se obtivesse a máxima absorção de água deionizada e foi montado num delineamento inteiramente casualizado, com seis doses de hidrogel (1, 2, 4, 6, 8 e 10 g L-1) e quatro repetições. O segundo estudo, montado num delineamento experimental inteiramente casualizado, com quatro repetições, consistiu em testar doses de sacarose P.A. (0, 1, 2, 4 e 6 %), afim de avaliar a alteração no potencial osmótico da solução sobre a hidratação do hidrogel. O terceiro e o quarto estudos foram desenvolvidos em delineamento inteiramente casualizado, num esquema fatorial 6 × 3 × 2, com quatro repetições. Para o terceiro estudo, os fatores constituíram de seis níveis de CE (0; 0,25; 0,50; 1,00; 1,50 e 2,00 mS cm-1), elevada pela adição de três ânions (NO3-; PO43- e SO42-), acompanhados pelos contra-íons Ca++ e K+. Para o quarto estudo, os mesmos seis níveis de CE foram atingidos pela adição de três cátions (Ca++, Mg++ e K+), acompanhados pelos contra-íons Cl- e SO42-. A capacidade de hidratação do hidrogel reduz com a elevação da concentração iônica da solução e que a redução do potencial osmótico, pela adição de sacarose, não interfere na sua capacidade de intumescimento. Os ânions e cátions em solução influenciam negativamente no processo de hidratação do hidrogel, sendo o efeito mais pronunciado para aqueles de maior valência..

ABSTRACT Hydrogel hydration capacity in solution was evaluated at different levels of electrical conductivity (EC) using nitrate, phosphates, sulfates, and salts of calcium, potassium and magnesium. Four sequential experiments were performed using potassium polyacrylate copolymer. The first experiment aimed to determine the lowest hydrogel dose, at which occur maximum deionized water absorption. The test was assembled in a completely randomized design with six hydrogel doses (1, 2, 4, 6, 8 and 10 g L-1) and four replicates. The second experiment consisted of testing the sucrose P.A. doses (0, 1, 2, 4 and 6 %) in order to evaluate the change in osmotic potential of the solution on hydrogel hydration. The third and fourth studies were carried out in a complete randomized design, using a 6 x 3 x 2 factorial scheme with four replicates. For the third experiment, the factors were six levels of EC (0; 0.25; 0.50; 1.00; 1.50 and 2.00 mS cm1) increased by the addition of three anions (NO3-; PO43- and SO42-) along with counter-ions Ca++ and K+. For the fourth experiment, the same six levels of EC were achieved by adding the three cations (Ca++, Mg++ and K+), along with the counter-ions Cl- and SO42-. Hydration capacity of the hydrogel decreases when the ionic concentration of the solution increases and the reduction of the osmotic potential through the addition of sucrose does not interfere in its swelling capability. Anions and cations in the solution negatively influence the process of the hydrogel hydration. The most pronounced effect is for those with higher valence.

Lupinus albescens é uma espécie frequente nos locais de arenização no Rio Grande do Sul, com alta rusticidade e rápida cobertura vegetal, mostrando potencialidades para recomposição de áreas degradadas. O objetivo foi avaliar a emergência e o desenvolvimento de L. albescens, com e sem aplicação de adubação mineral consorciada com a palmeira Butia lallemantii Deble & Marchiori. Sementes foram coletadas em três populações e submetidas à escarificação por 40 segundos. A sementeira foi feita entre nove fileiras (2 x 1 m) de B. lallemantii aplicando-se 0 e 30 g/cova do fertilizante mineral NPK (5-20-20). Avaliações: número de plantas por cova (NPC), altura (cm) e diâmetro do caule (mm), nos períodos de 30 e 60 dias, assim como a percentagem de emergência de plantas/m² (PEP) e o total emergência de plantas (TEP) ao longo de 240 dias, utilizando delineamento em blocos casualizados. Os resultados mostraram considerável PEP e altura aos 30 dias para as plantas do bloco 2. Dose de 0g/cova do fertilizante NPK proporcionou maior NPH. Portanto, a sementeira de L. albescens consorciada com B. lallemantii apresentou maior PEP, NPC sem o uso de adubação (30 dias) e maior altura das plantas entre as plântulas de diâmetro do estipe médio.

Lupinus albescens is a species frequent in the locals under arenization in Rio Grande do Sul, with high rusticity and rapid land cover, showing potentialities for recomposition of degraded areas. The objective was to evaluate the emergence and development of L. albescens, with and without mineral fertilizer application intercropped with the palm Butia lallemantii Deble & Marchiori. Seeds were collected in three populations and submitted to the scarification for 40 seconds. Sowing was done between nine rows (2 x 1 m) of B. lallemantii by applying 0 and 30 g/hole of the mineral fertilizer NPK (5-20-20). Evaluations: number of plants per hole (NPH), height (cm) and stem diameter (mm), in the periods of 30 and 60 days, as well as the percentage of plants emergence/m² (PEP) and the total of plants emergence (TEP) over 240 days, using randomized block design. The results showed a considerable PEP and height at 30 days for the plants in block 2. Dose of 0g/hole of fertilizer NPK provided higher NPH. Therefore, sowing of L. albescens intercropped with B. lallemantii presented higher PEP, NPH without the use of fertilization (30 days) and higher height of the plants among the diameter seedlings of the medium stipe.

Abstract Seasonality and lack of organic substrates suitable for the production of citrus rootstocks are the main problems in seedling production, coupled with the fact that these materials have alkaline pH. The objective of this study was to evaluate the effect of substrates composed of Pinus sp. needles and a commercial alkaline substrate at different concentrations on the growth and development of Poncirus trifoliata (L.) Raf rootstock. The development of 'Trifoliata' was assessed in different mixtures (v:v) of a commercial substrate (Vida®) based on eucalyptus bark and Pinus sp. needles (0, 25, 50, 75 and 100 %) with two particle sizes (3.5 and 8.0 mm). A randomized block experimental design with 10 treatments of seven plants each and four replications was used. During rootstock development, we monitored: the pH, electrical conductivity and stability of the substrates; the dry mass of the aerial part, roots and stem; and vegetative growth and development. Increasing the proportion of needles in the mixture with alkaline substrate reduced the pH, electrical conductivity and density. Treatments with 3.5 mm needles showed greater stability than those with 8 mm ones. The use of 25 % needles provided better results compared to 0 % (alkaline substrate only); however, the need for a specific fertilization and irrigation system for each treatment was detected, as each new substrate has its own physical and chemical characteristics.

Resumen La estacionalidad y carencia de sustratos orgánicos adecuados para la producción de portainjertos cítricos son de los principales problemas en la producción de plántulas, aunado al hecho de que estos materiales poseen pH alcalino. El objetivo de este trabajo fue evaluar el efecto de sustratos compuestos de acícula de Pinus sp. y un sustrato comercial alcalino a diferentes concentraciones sobre el crecimiento y desarrollo del portainjerto Poncirus trifoliata (L.) Raf. Se evaluó el desarrollo de ‘Trifoliata’ en distintas mezclas (v:v) de un sustrato comercial (Vida®) a base de corteza de eucalipto y acículas de Pinus sp. (0, 25, 50, 75 y 100 %) con dos granulometrías (3.5 y 8.0 mm). El diseño experimental fue en bloques al azar con 10 tratamientos de siete plantas cada uno y cuatro repeticiones. Durante el desarrollo de los portainjertos se monitoreó el pH, la conductividad eléctrica y la estabilidad de los sustratos, la masa seca de la parte aérea, raíces y tallo, además del crecimiento y desarrollo vegetativo. El aumento de la proporción de acículas en la mezcla con sustrato alcalino redujo el pH, la conductividad eléctrica y la densidad. Los tratamientos con acícula de 3.5 mm mostraron mayor estabilidad que los de 8 mm. El uso de 25 % de acícula proporcionó mejores resultados en comparación con el de 0 % (solo sustrato alcalino); no obstante, se detectó la necesidad de un sistema de fertilización y riego específico para cada tratamiento, ya que cada sustrato nuevo posee características físicas y químicas propias.

Abstract Angelonia integerrima Sprengel is a native species of the state of Mato Grosso do Sul and the Southern region (Paraná, Santa Catarina and Rio Grande do Sul) of Brazil, with features such as an unusual appearance and color of the flowers, indicating an ornamental use. To optimize the use of this species and to fill in gaps regarding its cytogenetic characterization, this study determined the chromosome number, meiotic index and pollen viability of plant individuals of four A. integerrima populations. All plant individuals of the four populations had 2n = 20 chromosomes. Still, the meiotic index of most analyzed plant individuals exceeded 90%, while pollen viability of all plant individuals was higher than 80%. These data suggest considerable cytological stability of the analyzed A. integerrima plant individuals, which may favor the selection of future genotypes for commercial purposes or their use in conservation and breeding programs of the species.

SUMMARY: One of the main abiotic factors that influence the growth and development of plants is water, and consequently the use of water stress-tolerant species increases the chances of success of crops in these conditions. The aim of this study was to evaluate the growth and initial development of Mimosa scabrella seedlings under different water regimes. Therefore, seeds were submitted to dormancy breaking and sowed in coir fiber substrate. After that, the seedlings were established in pots (8L capacity) containing composted pine bark substrate. The treatments consisted of five levels of pot capacity: 100 %, 75 %, 50 %, 25 % and 10 %. The experimental design was completely randomized with four replicates of five plants per treatment. There was influence of water regimes in most of the variables analyzed, where it was observed that with 50 % of pot capacity growth and development of plants showed satisfactory results. Moreover, the quality of the seedlings showed that in general, with only 25 % of the pot capacity plants have the ability to survive and settle under water stress conditions. Thus, the data indicate that Mimosa scabrella is a promising species for cultivation under water deficit, since the growth and initial development of seedlings occurred satisfactorily in conditions similar to these.

RESUMEN: El agua es uno de los principales factores abióticos que influyen en el crecimiento y desarrollo de las plantas; la utilización de especies más tolerantes al déficit hídrico aumenta las oportunidades de éxito de los cultivos en estas condiciones. El objetivo de este estudio fue evaluar el crecimiento y desarrollo inicial en plantines de Mimosa scabrella bajo diferentes regímenes hídricos. Con ese fin, un número determinado de semillas fueron sometidas a la superación de la latencia y sembradas en sustrato a base de fibra de coco. Posteriormente, las plantas fueron colocadas en macetas (capacidad de ocho litros), con sustrato de corteza compostada de pino. Los tratamientos fueron definidos por cinco niveles de contenido de agua: 100 %, 75 %, 50 %, 25 % y 10 %. Se utilizó un diseño completamente al azar con cuatro repeticiones de cinco plantas por tratamiento. Como resultado, hubo influencia de los regímenes hídricos en la mayoría de las variables analizadas, en las cuales se observó que hasta en 50 % de contenido de agua, el crecimiento y el desarrollo de las plantas presentaron resultados satisfactorios. La calidad de los plantines demostró, que en general, en un 25 % de contenido de agua las plantas presentan capacidad de sobrevivir y de establecerse en condiciones de estrés hídrico. Así, los datos apuntan que M. scabrella es una especie potencial para el cultivo bajo condiciones de estrés hídrico, pues el crecimiento y desarrollo inicial de los brinzales ocurrieron de forma satisfactoria en condiciones análogas a estas.

Resumo A produção de mudas de citros em ambiente protegido demanda grande quantidade de substrato, o qual deve apresentar características físicas e químicas adequadas. O uso de condicionadores ácidos, como acículas de Pinus, em mistura com substratos alcalinos, possibilita o cultivo de mudas com maior qualidade. O objetivo foi avaliar o desenvolvimento do porta-enxerto “Fepagro C37 Reck” cultivado em diferentes misturas do substrato comercial alcalino (Humosolo ES®) com acículas de Pinus elliottii. O experimento foi realizado testando misturas entre o substrato alcalino e acículas de Pinus com cinco meses de decomposição in situ e em duas granulometrias: 3,5 e 8,0 mm. As misturas foram realizadas em proporções entre as acículas com o Humosolo, (v/v) de 0%; 25%; 50%; 75% e 100%. Utilizaram-se bandejas alveoladas de poliestireno expandido para acomodação das misturas e semeadura do porta-enxerto. Realizaram-se avaliações físicas e químicas das misturas, bem como do desenvolvimento das mudas. A utilização de acícula de Pinus acidificou o substrato Humosolo ES®, reduziu sua condutividade elétrica e tornou as misturas com maior porcentagem de espaço poroso e menor retenção de água. Os tratamentos contendo mistura de 25 e 50% de acícula, indiferentemente da granulometria, proporcionam maior desenvolvimento de plantas do porta-enxerto “Fepagro C37 Reck”.

Abstract The production of citrus seedlings in protected environment requires a large amount of substrate, which must have adequate physical and chemical characteristics. The use of acidic conditioners, such as Pinus needles mixed with alkaline substrates, allows the cultivation of seedlings with better quality. The objective of this work was to evaluate the development of the “Fepagro C37 Reck” rootstock grown in different alkaline commercial substrate mixtures (Humosolo ES®) with Pinus elliottii needles. The experiment was carried out by testing alkaline substrate mixed with 5-month old of decomposition Pinus needles in situ decomposition and two granulometry sizes, 3.5 and 8.0 mm. The mixtures were performed in proportions between the needles with the Humosolo, (v / v) 0%; 25%; 50%; 75% and 100%. Expanded cellular polystyrene trays were used to accommodate the mixtures and seeding of the rootstock. Physical and chemical evaluateons of the mixtures were carried out, as well as the development of the seedlings. The use of Pinus needles acidified the substrate Humosolo ES®, reduced its electrical conductivity and increased the percentage of porous space of the mixtures and reduced water retention. The treatments containing 25 and 50% of the Pinus needles mixture, regardless of the granulometry, provide greater development of rootstock plants “Fepagro C37 Reck”.

ABSTRACT The stress caused by water saturation has negative consequences for plants. The search for species tolerant to flooded soils can make feasible the use of areas with these characteristics. The objective of this study was to observe the effect of water saturation levels on the initial growth of Mimosa scabrella Benth seedlings. Newly germinated seedlings were subjected to three water depths (without saturation, 1/3, and 2/3 above the pot capacity) in a greenhouse environment. After 173 days, it was verified that for most of the variables there was no difference between the control treatment and the two saturation levels. In addition, the analysis of seedling quality demonstrated the ability of the species to develop and survive in this condition. Therefore, it is inferred that bracatinga is a promising species for cultivation under water saturation conditions.

RESUMO Myrceugenia myrtoides (Myrtaceae) é uma espécie de porte arbóreo, com ocorrência restrita ao estado do Rio Grande do Sul no Brasil, e Uruguai, apresentando potencial ornamental. O interesse em espécies nativas para usos diversos é crescente, mas sua inserção é limitada devido à falta de informações sobre sua propagação e cultivo. Assim, o objetivo deste estudo foi avaliar os efeitos de temperatura e luz na germinação das sementes de M. myrtoides, a fim de gerar informações que possam auxiliar na propagação da espécie e exploração do seu potencial. Avaliaram-se os efeitos das temperaturas constantes de 20, 25 e 30 °C sob fotoperíodo de 16 horas. Para avaliar o efeito da luz, a germinação foi testada em ausência total de luz e sob fotoperíodo de 16 horas, na temperatura de 25 °C e intensidade luminosa de 27 e 33,75 µmol m−2s−1, sob qualidade de luz branca e luz verde difusa. Os resultados demonstraram menor tempo médio de germinação nas temperaturas de 25 e 30 °C e ainda, maior acúmulo de massa seca sob 30 °C. Houve superioridade nas variáveis de formação de plântula, comprimento de parte aérea e raiz e formação de plântulas sob número de sementes germinadas para a temperatura de 25 °C. Já as diferentes condições de luz testadas não afetaram a porcentagem de germinação. Conclui-se que a temperatura de 25 °C foi a mais adequada para a germinação de sementes e desenvolvimento de plântulas de M. myrtoides e as suas sementes são classificadas como fotoblásticas neutras.

ABSTRACT Myrceugenia myrtoides (Myrtaceae) is a species of tree size, occurring restricted to the state of Rio Grande do Sul state in Brazil, and Uruguay, presenting ornamental potential. The interest in native species for diverse uses is increasing, but their insertion is limited due to the lack of information on its propagation and cultivation. Thus, the objective of this study was to evaluate the effects of temperature and light on the germination of M. myrtoides seeds, in order to generate information that could aid in the propagation of the species and the exploration of its potential. The effects of constant temperatures of 20, 25 and 30 °C under a 16-hour photoperiod were evaluated. To evaluate the effect of light, the germination was tested in continuous darkness and under photoperiod of 16 hours, at a temperature of 25 °C and light intensity of 27 and 33.75 µmol m−2s−1 under white light quality and diffuse green light. The results showed a lower average germination time at temperatures of 25 and 30 °C and a higher accumulation of dry mass under 30 °C. There was superiority in the variables of seedling formation, shoot and root length and seedling formation under the number of seeds germinated at 25 °C. However, the different light conditions tested did not affect the percentage of germination. It is concluded that the temperature of 25 °C was the most adequate for seed germination and development of M. myrtoides seedlings and their seeds are classified as neutral photoblasts.

RESUMO A espécie florestal Toona ciliata var. australis possui madeira de alto valor econômico para móveis e seus plantios não são afetados pela Hypsipyla grandella, praga que ataca plantios de monocultura de espécies nativas semelhantes à Toona ciliata. Possui uma estreita relação com a água disponível, ocorrendo geralmente em florestas úmidas no seu ambiente natural. Em plantios comerciais, esse é um dos fatores que mais limita seu estabelecimento e crescimento inicial. Nas últimas décadas, sua área de plantio no Brasil foi ampliada, entretanto, é escasso o conhecimento sobre o efeito de ambientes adversos na germinação e crescimento inicial de plântulas. O objetivo deste trabalho foi avaliar os efeitos do estresse salino e hídrico na germinação e crescimento inicial de plântulas de Toona ciliata, utilizando-se soluções contendo, ou NaCl, ou PEG 6000, nos potenciais osmóticos: -0,1; -0,2; -0,3; -0,4; -0,5; -0,6; -0,9; -1,2 e -1,5 MPa, mais a testemunha, com água esterilizada. As sementes foram submetidas ao teste de germinação sobre papel-germitest umedecido com a solução correspondente, e incubadas a 25 ± 2°C e fotoperíodo de 16 h por 21 dias. O delineamento experimental foi o inteiramente casualizado, arranjado em esquema fatorial 2 × 10 (agentes osmóticos × potenciais osmóticos), com quatro repetições de 50 sementes cada. Conforme a redução do potencial osmótico observou-se menor germinação, número de plântulas normais, massa fresca, comprimento de plântula e maior número de sementes duras, sendo mais severo em PEG 6000. Portanto, houve mais sementes germinadas sob o efeito do NaCl do que do PEG 6000. Entretanto, apesar da germinação alta em NaCl, o número de plântulas anormais também foi maior que em PEG 6000. Concluise que a germinação e o crescimento inicial de plântulas de Toona ciliata são afetados tanto pelo estresse salino como hídrico, sendo as plântulas mais sensíveis ao estresse hídrico, e com maior probabilidade de desenvolver plântulas anormais sob estresse salino.

ABSTRACT The Toona ciliata var. australis is a tree species which yields a very high-quality timber for furniture and is unaffected by Hypsipyla grandella, a pest that attacks monoculture plantations of native species similar to Toona ciliata. It has a close relationship with water availability, occurring mainly in humid forest in its natural habitat. In commercial plantations this is an important limitation to the establishment and initial growing of Toona ciliata. In the last decades, the use of Toona ciliata in commercial plantations has increased in Brazil, however, there is little knowledge about the effect of adverse environments on seed germination and early seedling growth. This study aimed to evaluate the effects of water and saline stress on germination and early seedlings growth of Toona ciliata. Osmotic solutions were prepared with, or NaCl, or PEG 6000, in the following osmotic potentials: -0.1; -0.2; -0.3; -0.4; -0.5; -0.6; -0.9; -1.2 and -1.5 MPa. For the control treatment, it was only used sterile water. The seeds were submitted to the germination test in which the germitest paper was moistened with the relative osmotic solution. The incubation was realized in a germination chamber at 25 ± 2 °C with 16 h light of photoperiod. The experimental design was completely randomized, arranged in a factorial design 2 × 10 (osmotic agent × osmotic potential and control), with four repetitions of 50 seeds each. With the reduction on the osmotic potential was observed lower germination, number of normal seedlings, fresh weight, seedling length and higher number of hard seeds, being the effect of PEG 6000 more severe. The germination and number of abnormal seedlings was higher under NaCl effect than PEG 6000. It can be concluded that germination and early seedling growth of Toona ciliata are affected by both saline and water stress, being more sensitive under water stress and with higher probability of developing abnormal seedlings under saline stress.