Abstract In this research, we hypothesized that Ormosia arborea (Vell.) Harms seedlings should grow better and achieve greater levels of gas exchange when grown in soils with higher water availability. Thus, this study was developed to assess the metabolic responses of the seedlings to different levels water availability. Irrigation was performed on alternate days, at water holding capacities (WHC) of 25%, 50%, 75%, and 100%. The metabolic responses were analyzed at 15, 50, 85, and 120 days after starting treatments. The O. arborea plants grown in conditions of higher water availability (75% and 100% WHC) had higher leaf water potential and chlorophyll content, in addition to higher values for chlorophyll a fluorescence and gas exchange, than those grown in other conditions. Water deficit caused by low levels of water availability (25% or 50% WHC) reduces leaf water potential, chlorophyll a fluorescence, and gas exchange. As a strategy to tolerate stress, seedlings tend to invest in their antioxidant system, as shown by the high levels of activity of the enzymes Superoxide dismutase (SOD), Peroxidase (POD), and Catalase (CAT). Although the seedlings may be tolerant to cultivation under 50% WHC, the best functioning of the photosynthetic apparatus occurred under WHC of 75%.

Resumo Nesta pesquisa, hipotetizamos que as mudas de Ormosia arborea (Vell.) Harms crescem melhor e alcançam maiores níveis de troca gasosas quando cultivadas em solos com maior disponibilidade de água. Assim, este estudo foi desenvolvido para avaliar as respostas metabólicas das mudas a diferentes níveis de disponibilidade hídrica. A irrigação foi realizada em dias alternados, nas capacidades de retenção de água (CRA) de 25%, 50%, 75% e 100%. As respostas metabólicas foram analisadas aos 15, 50, 85 e 120 dias após o início dos tratamentos. As plantas de O. arborea cultivadas em condições de maior disponibilidade hídrica (75% e 100% CRA) apresentaram maior potencial hídrico foliar e teor de clorofila, além de maiores valores para a fluorescência da clorofila a e trocas gasosas do que aquelas cultivadas em outras condições. O déficit hídrico causado por baixos níveis de disponibilidade hídrica (25% ou 50% CRA) reduz o potencial hídrico foliar, a fluorescência da clorofila a e as trocas gasosas. Como estratégia para tolerar o estresse, as mudas tendem a investir em seu sistema antioxidante, como demonstrado pelos altos níveis de atividade das enzimas Superóxido dismutase (SOD), Peroxidase (POD) e Catalase (CAT). Embora as mudas possam ser tolerantes ao cultivo com menos de 50%, o melhor funcionamento do aparato fotossintético ocorreu sob 75% de CRA.

Resumo Myrciaria glomerata O. Berg. (Myrtaceae) é uma frutífera nativa da Mata Atlântica com potencial alimentício, medicinal e ecológico, mas com baixa taxa de germinação. Objetivou-se com este trabalho avaliar diferentes métodos na superação da dormência de sementes e no vigor de plântulas de M. glomerata. Foram realizados dois experimentos. No experimento 1, foram testados sete tratamentos: controle; imersão em água a 100 ºC por 30 segundos; imersão em ácido sulfúrico concentrado (H2SO4) por 1 e 5 minutos; imersão em solução aquosa de ácido giberélico (AG3) 250 e 500 mg L-1 e imersão em solução aquosa com 5 mL de Stimulate® kg-1 de sementes. No experimento 2, foram testadas sete doses de Stimulate®: 0; 5; 10; 15; 20; 25 e 30 mL kg-1 de sementes. A imersão das sementes em 250 e 500 mg L-1 AG3 contribui na velocidade de germinação e maior comprimento, massas frescas e secas, em comparação às do controle e aos outros métodos testados. A imersão em água a 100 ºC e em H2SO4 não é recomendada para M. glomerata. As doses de 20 a 25 mL de Stimulate® kg-1 de sementes proporcionam incremento para todas as características anali-sadas. Imersão em AG3, na concentração de 250 mg L-1, e doses de 15 a 25 mL de Stimulate® kg-1 de sementes são eficientes para a superação da dormência de sementes e o vigor de plântulas de M. glomerata.

Abstract Myrciaria glomerata O. Berg. (Myrtaceae) is a fruit tree native to the Brazilian Atlantic Forest with potential for use as food and medicine, besides having good ecological potential. However, this species is limited by low germination rates. Thus, this study aimed to evaluate different methods to overcome dormancy in seeds of M. glomerata and to improve seedling vigor. For this, two experiments were conducted. In Experiment 1, seven treatments were tested: a control treatment, immersion in water at 100 ºC for 30 seconds, immersion in concentrated sulfuric acid (H2SO4) for 1 and 5 minutes, immersion in an aqueous solution of gibberellic acid (GA3) at the concentrations of 250 and 500 mg L-1 for 24 h, and seeds homogenized with an aqueous solution of Stimulate® at a concentration of 5 mL kg-1 seed. In Experiment 2, six doses of Stimulate® were tested: 0, 5, 10, 15, 20, 25, and 30 mL kg-1 seed. The immersion of seeds in 250 and 500 mg L-1 GA3 contributes to increase germination rates, seed length, fresh mass, and dry mass compared to the control and the other methods tested. Immersions in water at 100 ºC and in H2SO4 are not recommended for M. glomerata. The treatment with Stimulate® at 15–25 mL kg-1 seed increased all characteristics analyzed. Immersion in 250 mg L-1 GA3 and Stimu-late® at 20–25 mL kg-1 seed efficiently stimulated seeds to overcome dormancy in M. glomerata, as well as improved seedling vigor.

Resumo O objetivo deste estudo foi avaliar o potencial do sombreamento na redução do efeito estressante do déficit hídrico sobre o metabolismo fotossintético e antioxidante, favorecendo o crescimento de mudas de Ormosia arborea e sua recuperação metabólica. Os níveis de sombreamento estudados foram: 0, 30 e 70%. Foram implantados dois regimes hídricos: controle, em que as plantas foram irrigadas a 75% da capacidade de retenção de água no solo e restrição hídrica, em que a irrigação foi suspensa até que a taxa fotossintética atingisse valores próximos a zero (F0), período em que as mudas foram re-irrigadas. Ocorreram dois períodos de avaliação: F0 e recuperação. Observamos que a restrição hídrica reduz o metabolismo fotossintético, o crescimento e a qualidade das mudas de O. arborea, aumentando a atividade de enzimas antioxidantes. As mudas apresentam maior índice de qualidade, condutância estomática, eficiência de carboxilação da Rubisco e transpiração quando cultivadas sob sombreamento de 70% na recuperação. O efeito estressante da restrição hídrica foi mitigado pelo sombreamento de 70% quando as mudas foram capazes de se recuperara, retomando seu metabolismo fotossintético e qualidade após a retomada da irrigação. Além disso, 0% de sombreamento não é indicado para essa espécie.

Abstract This study aimed to evaluate the potential of shading in reducing the stressful effect of water restriction on photosynthetic and antioxidant metabolism, favoring the growth of Ormosia arborea seedlings and the recovery metabolic. The shadings levels studied were: 0, 30 and 70%. Two water regimes were implemented: control, in which the plants were irrigated at 75% of soil water retention capacity and water restriction, in which the irrigation was suspended until the photosynthetic rate reached values close to zero (P0), period at which the seedlings were re-irrigated. There were two evaluation periods: P0 and recovery. We observed that water restriction reduced photosynthetic metabolism, growth and quality of O. arborea seedlings by increasing the activity of antioxidant enzymes. The seedlings present higher quality index, stomatal conductance, intrinsic carboxylation efficiency and transpiration when cultivated under 70% shading in recovery. The stressful effect of water restriction was mitigated by the shading of 70%, where the seedlings were able to recover, resuming their photosynthetic metabolism and quality after resumption of irrigation. In addition, 0% shading is not indicated for this species.

Resumo O alagamento do solo restringe a disponibilidade do oxigênio necessário para ativação dos processos fisiológicos do embrião e que caracterizam a germinação de sementes. No entanto, algumas espécies apresentam adaptações que permitem seu crescimento natural em áreas sujeitas a inundações, como Ormosia arbórea, espécie nativa da Mata Atlântica e do Cerrado. O objetivo deste trabalho foi avaliar como a germinação e emergência das sementes desta espécie foram afetadas pela submersão em água e escarificação. No experimento 1, as sementes foram escarificadas por 15 minutos em ácido sulfúrico e posteriormente semeadas em tubetes submersos em água por 0, 15, 30 e 45 dias. Nos experimentos 2 e 3, as sementes foram submersas em água corrente pelo mesmo período e, após cada tempo de submersão, foram escarificadas por 0, 5, 10 e 15 minutos em ácido sulfúrico e semeadas em tubetes e em papel Germitest®. Verificou-se que, após a quebra da dormência tegumentar, 15 dias de alagamento são suficientes para inviabilizar a germinação das sementes de O. arborea que toleram a submersão em água quando estão intactas. Este resultado indica que o tegumento rígido e impermeável da semente é uma importante característica da semente para essa resposta.

Abstract Soil flooding restricts the availability of the oxygen necessary to activate the embryonic physiological processes that characterize seed germination. However, some species have adaptations that allow them to grow naturally in areas prone to flooding, such as Ormosia arborea, a native species of the Atlantic forest and the Cerrado. The objective of this work was to evaluate how seed germination and emergence in this species were affected by submersion in water and scarification. In experiment 1, the seeds were scarified by 15 minutes in sulfuric acid and was subsequently sown in tubes submerged in water for 0, 15, 30 and 45 days. In experiments 2 and 3, seeds were submerged in running water for the same period and, after each time of submersion, were scarified by 0, 5, 10 and 15 minutes in sulfuric acid and sown either in tubes and in Germitest® paper. It was found that, after breaking the tegumental dormancy, 15 days of flooding is enough to derail the germination of O. arborea seeds that tolerate submersion in water when they are intact. This response indicates that the hard, impermeable seed coat is an important seed characteristic for this response.

ABSTRACT The objective of this work is to evaluate the use of modified atmosphere and chitosan as an alternative to chemical treatment in postharvest conservation of ‘Tainung 1’ papaya under refrigeration. The experiment comprised of completely randomized blocks with four replications, one fruit per replication, with a 2 × 4 × 4 factorial design as follows: two types of packaging (with or without polyvinyl chloride [PVC] stretchable film, thickness of 17 µm), four treatments (control, 2% chitosan, 4% chitosan, and prochloraz fungicide with 33.75 g a.i.·100 L–1), and four storage periods (0, 7, 14, and 21 days) at 10 °C and relative humidity (RH) of 90 ± 5%. The variables evaluated were mass loss (ML), external appearance, titratable acidity (TA), soluble solids (SS), vitamin C, reducing sugars (RS), and total sugars (TS). The storage of ‘Formosa’ papaya under refrigeration at 10 °C and RH of 90 ± 5% associated with PVC provided a low percentage of ML and longer conservation time of apparent quality (up to 7 days) in relation to fruits with no storage in PVC. The external appearance of fruits was preserved for up to 14 days by the PVC + 4% chitosan treatment and for up to 21 days by the PVC + prochloraz fungicide treatment. The treatment PVC + 4% chitosan associated with refrigeration is efficient in maintaining fruit quality. It is, for up to 14 days, a viable alternative to the use of prochloraz fungicide for postharvest conservation of ‘Formosa’ papaya.

Abstract The aim this study was to evaluate the effect of salicylic acid (SA) in Schinus terebinthifolia seedlings subjected to irrigation intervals. The experiment was performed by 78 days, under four irrigation intervals: 0, 4, 8, and 12 days, in combination with four concentrations SA: 0, 50, 100, and 200 mg L-1. The irrigation was individually maintaining water retention capacity of 100%, under each irrigation intervals. The maximum height across the irrigation intervals was 24.74 cm at 7-days intervals, and 24.31 cm with 200 mg L-1 of SA. The largest leaf areas were 116.03 cm2 at 12-day interval and 123.71 cm2 with 200 mg L-1 of SA. The highest production of dry masses of leaves, stem and roots was without and 12-days intervals, both with 200 mg L-1 of SA. Exogenous application of 200 mg L-1 of SA contributed on increased growth in S. terebinthifolia seedlings subjected to 12-days irrigation interval.

Resumo O uso de tecnologias alternativas que envolvem processos biológicos, com ganhos econômicos e ecológicos, é desejável para a expansão da bananicultura e a renovação de áreas que apresentam baixas produtividades. Os fungos micorrízicos arbusculares (FMAs) têm a capacidade de estimular o crescimento das plantas, especialmente por meio do incremento na absorção do fósforo (P) e de outros nutrientes. Objetivou-se, neste trabalho, verificar a influência dos FMAs sobre o crescimento e a fisiologia de mudas micropropagadas de bananeira submetidas a doses de P. O delineamento experimental adotado foi o de blocos casualizados, em arranjo fatorial 5 x 5, sendo os fatores inoculação com os FMAs (Glomus clarum, Gigaspora margarita, Gigaspora albida e Clareoideoglomus etunicatum e o controle sem FMAs), e cinco doses de P (0; 50; 100; 200 e 400 mg kg-1), com quatro repetições. A aplicação de doses de P proporcionou maior crescimento das mudas micropropagadas de bananeira, independentemente da inoculação micorrízica. As maiores taxas de colonização micorrízica foram observadas nas menores doses de P, sendo a dose de 50 mg kg-1 de P a que proporcionou melhores condições na formação de micorrizas para todas as espécies de FMAs avaliadas. As simbioses com FMAs e o uso de P proporcionaram aumento da taxa de fotossíntese das plantas, favorecendo o crescimento, o desenvolvimento e a qualidade de mudas de bananeira.

Abstract The use of alternative technologies involving biological processes, with economic and ecological gains, is desirable for both the expansion of Musa spp. farming and the renovation of areas with low yields. Arbuscular mycorrhizal fungi (AMF) can stimulate plant growth, especially by increasing the absorption of phosphorus (P) and other nutrients. This study analyzes the influence of AMF on the growth and physiology of micropropagated Musaspp. plants submitted to doses of P. The experimental design was randomized blocks, in a 5 x 5 factorial arrangement, in which the factors were inoculation with AMF (Glomus clarum, Gigaspora margarita, , Gigaspora albida,Clareoideoglomus etunicatum, and the control without AMF) and five doses of P (0, 50, 100, 200, and 400 mg kg-1), with four replicates. The application of P doses increased growth in micropropagated Musaspp. seedlings, regardless of mycorrhizal inoculation. The highest rates of mycorrhizal colonization occurred at the lowest P doses, and the dose of 50 mg kg-1 P provided better conditions for mycorrhizal formation in all AMF species under study. The symbioses with AMF, as well as the use of P, increased photosynthesis rate, thus favoring the growth, development, and quality of Musa spp. seedlings. Species G. clarum, C. etunicatum, and G. margarita were the most promising for plant growth.

Abstract The present work evaluated the physical-anatomical and initial growth of Tabebuia roseoalba seedlings exposed to different water regimes. The seedlings were grown under 100, 50, 25 and 12.5% of the water retention capacity (WRC). After 90 days, the following aspects were evaluated: height, diameter, fresh and dry weights of aerial and root, root length, and leaf area, Dickson quality index, liquid assimilation rate, relative growth rate, specific leaf area, stomatal index, and number of trichomes and leaf epidermal cells. The results indicated seedlings have greater initial growth and quality when cultivated at 100% WRC, and 25 and 12.5% WRC represented stress conditions for the plants. The species is hypostomatous with anomocytic stomata. The number of stomata, the stomatal index, and the number of epidermal cells did diminish with reduced water availability. The number of trichomes were larger on the adaxial face as water availability decreased.

Abstract In this study, we assessed the gas exchange in Caryocar brasiliense seedlings in water deficit conditions and their capacity to recover after rehydration. We assessed plant photosynthetic rates, internal carbon concentrations, stomatal conductance, transpiration rates, water-use efficiency, instantaneous carboxylation efficiency, chlorophyll index, and photosystem II quantum efficiency. All gas exchange parameters were reduced after the suspension of irrigation. Seedling photosynthetic rates approached zero after 12 days. The equilibrium was reestablished in all variables 11 days after re-initiating irrigation, with the exception of internal CO2 concentration and stomatal conductance. Exposure of seedlings to water stress resulted in drastically reduced photosynthetic processes. This reduction occurred due to the limitation of stomatal conductance and low rubisco carboxylation efficiency but not to irreversible damage photosystem II. All of these parameters demonstrated recuperation with rehydration, but only the photosynthetic rates reached initial control values.

Pereskia aculeata Plum. (Ora pro nóbis, Cactaceae) é uma planta de interesse medicinal e de valor alimentício por apresentar elevadores teores de fibras e proteínas. Porém, são incipientes informações referentes aos aspectos fisiológicos na fase de crescimento inicial de mudas. Assim, objetivou-se com este trabalho conhecer o metabolismo fotossintético de mudas de P. aculeata propagadas por estaquia sob contrastes de irradiância. O experimento foi desenvolvido sob duas disponibilidades luminosas (Pleno sol e sombreamento de 50%), avaliando-se os tipos de estaca apical, mediana e basal. O arranjo experimental foi em esquema fatorial 2 x 3, no delineamento blocos casualizados, com quatro repetições. Foram quantificados os pigmentos fotossintéticos, emissão da fluorescência da clorofila a e trocas gasosas. Constatou-se que os maiores teores de clorofilas e eficiências fotoquímicas ocorreram nas mudas de estacas apicais cultivadas sob 50% de sombreamento (baixa irradiância). As maiores taxas de assimilação de CO2, eficiência da Rubisco e de uso da água foram constatadas quando utilizadas estacas medianas e basais sob pleno sol (alta irradiância). A propagação por estacas medianas mantidas em alta ou baixa irradiância e basais em alta irradiância propiciaram maior capacidade fotossintética das mudas e podem ser indicadas para a propagação dessa espécie.

Pereskia aculeata Plum. (Ora pro nóbis, Cactaceae) is a plant of medicinal interest and alimentary value to present high contents of fibers and proteins. However, information regarding the physiological aspects in the initial growth stage of seedlings is incipient. Thus, the aim of this work was to know the photosynthetic metabolism of P. aculeata seedlings propagated by cuttings under irradiance contrasts. The experiment was conducted under two light conditions (full sun and 50% shading), evaluating the types of apical, median and basal cuttings. The experimental arrangement was in a 2 x 3 factorial scheme, in the randomized complete block design, with four replications. Photosynthetic pigments, chlorophyll-a fluorescence emission and gas exchange were quantified. Results showed that the highest levels of chlorophylls and photochemical efficiencies were observed in the apical cuttings cultivated under 50% shading (low irradiance). The highest rates of CO2 assimilation, Rubisco efficiency and water use were observed when using median and basal cuttings under full sun (high irradiance). The propagation by median cuttings maintained in high or low irradiance, and basal cuttings under high irradiance provided a greater photosynthetic capacity of the seedlings, and may be indicated for the propagation of this species.

ABSTRACT The aim of the present study was to evaluate the effect of different concentrations of abscisic acid (ABA) on photosynthetic metabolism and antioxidant enzyme activity in seedlings of Calophyllum brasiliense grown under water deficit. The experiment was carried out in a completely randomized design with six treatments: 1) daily irrigation without ABA (I 0 ABA); 2) daily irrigation + ABA 10 µM (I 10 ABA); 3) daily irrigation + ABA 100 µM (I 100 ABA); 4) suspension of daily irrigation without ABA (E 0 ABA); 5) suspension of daily irrigation + ABA 10 µM (E 10 ABA); 6) suspension of daily irrigation + ABA 100 µM (E 100 ABA). According to results, suspending irrigation decreased gas exchange and water potential, affecting negatively the functioning of the photochemical apparatus, increasing antioxidant enzyme activity. The decrease in stomatal conductance was accompanied by a decrease in photosynthetic and transpiration rates, but seedlings treated with 10 µM ABA presented a higher photosynthetic rate than the remaining treatments under water deficit. Seedlings under water restriction showed recovery after reirrigation of all studied parameters until the end of the experiment, to values similar to those of control plants. Intermittent water deficit decreased plant water status and gas exchange, and increases the antioxidant enzyme activity. Application of 10 µM ABA minimizes the effects of water deficit and increases the antioxidant activity of superoxide dismutase (SOD) in the leaves in C. brasiliense seedlings and improve plant recovery after resuming irrigation, preserving the integrity and functioning of photosynthetic apparatus.

ABSTRACT The knowledge of the germination responses of seeds from plants growing along river margins or in areas susceptible to flooding is an important factor in the adoption of restoration practices. Considering that maturation of fruits of Genipa Americana L. when river margins are flooded, we raised some questions: Is seed germination of this species affected by water submersion, and, do distinct seed populations present differences in germination? Seeds of G. Americana were submerged in water for different periods to assess the germination and growing responses, using populations from different locations. Water submersion decreased the germination percentage and the germination speed index, and increased seed mean germination time in both populations. Growth was found to be hampered for most variables in the different seed populations. The adaptation of G. Americana to flooding involves the seeds being tolerant to submersion, with this factor not being effective in distinguishing populations studied here.

RESUMO: Este trabalho teve por objetivo avaliar, in vitro e in vivo, a eficácia de produtos naturais no controle da antracnose do mamão. Os experimentos in vitro foram instalados em delineamento inteiramente casualizado, sendo para a avaliação de crescimento micelial considerado o esquema fatorial 10 × 4 (tratamentos x períodos de avaliação) com oito repetições, com a esporulação avaliada ao final do experimento. Os tratamentos utilizados foram: extrato aquoso nas concentrações de 5 e 15% de Syzygium aromaticum (L.) Merr. & Perry (cravo-da-índia), Cinnamomum zeylanicum Breym (canela) e Zingiber officinalis Rox (gengibre), quitosana 1 e 3%, fungicida Procloraz a 100 µg.mL-1 e testemunha (sem tratamento). Para a avaliação da germinação de conídios, foram considerados seis tratamentos com cinco repetições. Foram utilizados os mesmos tratamentos, porém, nas concentrações de 7,5% de cada extrato (cravo-da-índia, canela e gengibre), 1,5% de quitosana, e 50 µg.mL-1 de Procloraz. Para o experimento in vivo, foram utilizados mamões “Formosa” “Tainung 1”, em delineamento inteiramente casualizado, sendo seis tratamentos com quatro repetições para avaliação de severidade de antracnose causada por Colletotrichum gloeosporioides. Os frutos foram tratados por imersão durante 5 minutos com extratos de cravo-da-índia, canela e gengibre a 15%, quitosana a 8% e testemunha com água destilada, e imersão por 2 minutos em fungicida Procloraz (33,75 g i.a./100 L). Os tratamentos com extrato de cravo-da-índia a 15% e quitosana a 8% foram eficazes em todas as avaliações, sendo uma alternativa viável ao fungicida Procloraz. Os tratamentos com extrato de gengibre foram menos eficientes, com controle intermediário para o extrato de canela.

ABSTRACT: We evaluated the efficacy of natural products in the control of papaya anthracnose, in vitro and in vivo. The in vitro experiments for evaluation of mycelial growth used a completely randomized 10 × 4 factorial design (treatments × evaluation periods) with eight replicates, with sporulation evaluated at the end of the experiment. The treatments involved the use of aqueous extract at concentrations of 5 and 15% for Syzygium aromaticum (L.) Merr. & Perry (clove), Cinnamomum zeylanicum Breym (cinnamon), and Zingiber officinalis Rox. (ginger); 1 and 3% chitosan; the fungicide Prochloraz at 100 µg.mL-1; and a control (no treatment). For evaluating conidia germination, we used six treatments with five replicates. The treatments included 7.5% of each extract (clove, cinnamon, and ginger), 1.5% chitosan, and 50 µg.mL-1 of Prochloraz. For the in vivo experiment, “Formosa” papaya “Tainung 1” was used in a completely randomized design, with six treatments and four replicates to evaluate the severity of anthracnose caused by Colletotrichum gloeosporioides. The fruits were treated by immersion for 5 min with 15% clove, cinnamon, and ginger extracts, 8% chitosan, and control with distilled water, and immersion for 2 min in Prochloraz (33.75 g a.i./100 L). The treatments with 15% clove extract and 8% chitosan were effective in all evaluations, resulting in a viable alternative to the fungicide Prochloraz. The treatments with ginger extract were less effective and those with cinnamon offered intermediate control.

RESUMO Schinus terebinthifolius Raddi é uma espécie arbórea que pode ser utilizada em recuperação de áreas degradas, sendo uma espécie de rápido crescimento com um sistema radicular bem expansivo o que facilita captar águas nas camadas mais profundas do solo. O objetivo deste trabalho foi avaliar o metabolismo fotossintético e enzimático das mudas de S. terebinthifolius sob condições de déficit hídrico e seu potencial de recuperação após a retomada de irrigação. O experimento foi realizado em casa de vegetação sob cobertura plástica onde os vasos foram distribuídos em dois lotes sendo: 1 - Controle, onde a irrigação das plantas foi mantida a 70% da capacidade de retenção de água e o lote 2 - Estresse, onde a suspensão da irrigação foi mantida até que a taxa fotossintética apresentasse níveis próximos de zero seguida de reidratação por 12 dias e nova suspensão da irrigação. No início do experimento e na suspensão da irrigação e reidratação, as plantas foram avaliadas quanto as trocas gasosas e enzimas antioxidantes. O estresse hídrico reduz significativamente a fotossíntese, a transpiração condutância estomática, a eficiência de carboxilação da rubisco e os teores de clorofila das plantas de S. terebinthifolius. As enzimas antioxidantes aumentaram tanto na parte aérea quanto na raiz em resposta ao déficit hídrico.

ABSTRACT Schinus terebinthifolius Raddi is a tree species that can be used in the recovery of degraded areas, as it exhibits rapid growth and has a very expansive root system, facilitating water uptake from the deeper layers of the soil. The objective of this study was to evaluate photosynthesis and enzymatic activity in S. terebinthifolius seedlings under conditions of water deficit and their potential to recover following re-irrigation. The experiment was conducted in a greenhouse under a plastic covering where plants were distributed into two groups: Group 1 - control plants, where irrigation was maintained at 70% of the water retention capacity, and Group 2 - stressed plants, where irrigation was suspended until the photosynthetic rate neared zero, followed by rehydration for 12 days, then a further suspension of irrigation. At the beginning of the experiment and during the suspension of irrigation and rehydration, plants were evaluated for gas and antioxidant enzyme exchanges. Hydric stress significantly reduced photosynthesis, stomatal transpiration conductance, carboxylation efficiency of Rubisco, and the chlorophyll content of the S. terebinthifolius plants. Following rehydration, plants recovered the carboxylation efficiency of Rubisco, but not the photosynthetic rate. Antioxidant enzyme activity increased in both the aerial part and the root in response to water deficit.

RESUMO Objetivou-se determinar o tipo de substrato e as melhores condições de luminosidade para o cultivo de mudas de Tocoyena formosa (Cham. & Schltdl.) K. Schum. A semeadura ocorreu em bandejas de isopor sob sombrite de 70% e três meses após a emergência, as plântulas foram selecionadas e em seguida transplantadas em vasos de 4L, em dois tipos de substratos: 50% de solo Latossolo Vermelho Distroférrico + 50% de areia (TA) e 50% de solo de Latossolo Vermelho Distroférrico + 25% de areia + 25% de cama de frango semidecomposta (TACF). Após o transplante, as mudas foram levadas para três condições de sombreamento (30%, 50% e 70% de sombra) e a pleno sol (0%). Após a aclimatação, a qualidade siológica das mudas foi determinada mensalmente, através da análise de crescimento e do índice de qualidade de Dickson, durante 90 dias. O experimento foi realizado em DIC em esquema fatorial 2 x 4 x 4 (substratos x sombreamento x idade da muda), com três repetições de três mudas. Foi observado maior crescimento e qualidade das mudas em substrato terra + areia + cama de frango e nas condições de 30% de sombra e pleno sol. Conclui-se que para produção de mudas de Tocoyena formosa a melhor condição de luminosidade é 30% de sombra e em pleno sol em substrato TACF.

ABSTRACT The aim of this study was to determine the best substrate type and light conditions for the cultivation of seedlings of Tocoyena formosa (Cham. & Schltdl.) K. Schum. Seeds were planted in Styrofoam trays under 70% shading. Three months after emergence, the seedlings were selected and transplanted in 4-L pots, in two types of substrates: 50% dystroferric Red Latosol + 50% sand (TA) and 50% dystroferric Red Latosol + 25% sand + 25% semi-decomposed chicken manure (TACF). After transplanting, the seedlings were placed under three conditions of shading (30, 50 and 70% shade) and full sun (0% shade). After acclimation, the physiologic quality of the seedlings was determined monthly, by analysis of growth and Dickson quality index, for 90 days. The experiment was carried out using a randomized block design in a 2 x 4 x 4 factorial scheme (substrate x shading x age of seedling), with three repetitions of three seedlings. There was greater growth and quality of the seedlings in the substrate soil + sand + chicken manure and under conditions of 30% shade and full sun. It is concluded that for the production of seedlings of Tocoyena formosa, the best conditions are 30% shade and full sun for light and TACF for substrate.