Objetivou-se revisar e propor o protocolo de viabilidade das sementes da Bertholletia excelsa pelo teste de tetrazólio. Sementes oriundas de plantio comercial propagado por enxertia com 16 anos de idade implantadas na Fazenda Iracema em Cláudia, MT, foram destegumentadas e cortadas longitudinalmente, depois foram hidratadas em água por imersão direta (ID) e papel toalha Germitest^® (PG) por 24 e 48 h e embebidas nas concentrações de 0,1 e 0,5% do sal de tetrazólio por 12 e 24 h no escuro à 30 °C. O delineamento experimental foi completamente randomizado em fatorial 2 x 2 x 2 x 2 (forma de embebição x tempo em embebição x tempo em solução de tetrazólio x concentração da solução de tetrazólio) com quatro repetições de 8 sementes. O teste de tetrazólio foi eficiente para colorir e identificar as sementes viáveis e inviáveis. A avaliação da viabilidade das sementes da B. excelsa destegumentadas e partidas ao meio foi melhor na condição de embebição com imersão direta em água por 24 h e concentração de 0,5% do sal tetrazólio por 24 h à 30 °C e embebição em papel toalha Germitest® por 24 h e concentração de 0,5% do sal tetrazólio por 12 h à 30 °C. Palavras-chave: Bertholletia excelsa Humb. & Bonpl; potencial fisiológico; sementes florestais; recalcitrância. VIABILITY OF BRAZIL NUTS SEEDS BY TETRAZOLIUM TEST   ABSTRACT: The objective was to review and propose the protocol of viability of Bertholletia excelsa seeds by tetrazolium test. Seeds from the commercial planting propagated by grafting with 16-year-old implanted at Fazenda Iracema in Cláudia, MT, were undegumented and cut longitudinally, then hydrated in water by direct immersion (ID) and Germitest® paper towel (PG) for 24 and 48 h and soaked in concentrations of 0.1 and 0.5% of tetrazolium salt for 12 and 24 h in the dark at 30 ° C. The experimental design was completely randomized in a factorial design 2 x 2 x 2 x 2 (soaking form x soaking time x time in tetrazolium solution x tetrazolium solution concentration) with four replications of 8 seeds. The tetrazolium test was efficient to color and identify viable and unviable seeds. The evaluation of viability of detegumented and cut longitudinally B. excelsa seeds was better in: direct soaking in water for 24 h and concentration of 0.5% of tetrazolium salt for 24 h at 30 ° C and soaking in Germitest® paper towels for 24 h and a concentration of 0.5% of the tetrazolium salt for 12 h at 30 ° C. Keywords: Bertholletia excelsa Humb. & Bonpl; physiological potential; forest seeds; recalcitrance.

Os aceiros químicos consistem em faixas com aplicações de retardantes do fogo utilizados no combate indireto de incêndios florestais. Embora eficiente, a inexistência de recomendações de uso prático restringe a aplicação e eficácia dos produtos. Objetivou-se avaliar a eficiência de retardantes do fogo em queimas controladas em área de Eucalyptus urograndis (Eucalyptus grandis x Eucalyptus urophylla) (clone H13) com 6,0 anos de idade, por meio da aplicação de diferentes concentrações e volumes de calda, considerando 1,0 h como tempo pós-aplicação. Foram avaliados três retardantes do fogo: dois comerciais (Phos-Chek WD881® e Hold Fire®) e um alternativo (polímero hidrorretentor: Nutrigel®) com cinco concentrações e nos volumes de calda de 0,5; 1,0 e 2,0 L m-2 (apenas água e sem aplicação de calda foram as referências). O comportamento do fogo foi avaliado pela velocidade de propagação do fogo, comprimento das chamas (e suas respectivas taxas de reduções) e material combustível remanescente e consumido. Para todos os retardantes, o aumento do volume de calda propiciou redução das variáveis do comportamento do fogo, sendo recomendado a aplicação de calda equivalente a 2,0 L m-2. As eficiências do Phos-Chek WD881® e do Hold Fire® apresentaram comportamentos lineares crescentes indicando que o aumento da concentração propiciou maior do controle do fogo, todavia, o Nutrigel® apresentou eficiência com resposta quadrática ao incremento das concentrações. A concentração ideal variou de acordo com o produto, sendo recomendado 1,0 mL L-1; 1,5 mL L-1; 0,0060 g L-1 para Phos-Chek WD881®, Hold Fire® e Nutrigel®, respectivamente.

Aiming to support projects and managements of irrigation for vegetables in the Mid-North region of Mato Grosso state, Brazil, this paper determined crop evapotranspiration (ETc), crop coefficients (Kc) and water response function of summer squash (Curcubita pepo) cv. ‘Italiana’ under different cultivation conditions. The plantations were conducted in the dry season of the region (July to October 2016), using 2.5 kg m^-2 of millet straw (grass) and crotalaria straw (legume) and bare soil. ETc was obtained by soil water balance through tensiometry, whereas Kc values were given by the ratio between ETc and the reference evapotranspiration (ETo) obtained by the FAO-56 Penman-Monteith method. For the water response function, the rates of 40, 60, 80, 100 and 120% ETc were applied, in which case the Class A pan method was used to obtain ETo. The different soil covers did not influence the ETc, Kc and accumulated thermal sum in the phenological stages of the summer squash. Kc values were 0.1, 0.25, 0.38 and 0.41, for the phenological stages I to IV, with average durations of 8, 46, 16, and 20 days, respectively. Increase in irrigation depths did not influence the rates of production of male and female flowers, but affected yield and decreased water use efficiency, regardless of soil cover.

This paper aimed to evaluate the growth, gas exchange and Chl a fluorescence in ipê-rosa seedlings, subjected to levels of 100, 75, 50 and 25% of water replacement (LWR), in a greenhouse. The morphometric variables of plant height, diameter at stem height, number of leaves and leaflets, root length and volume, plant dry mass and leaf area were evaluated. The potential evapotranspiration of seedlings (ETc) was obtained using direct weighing, considering as a reference the water replacement of 100% of the mass variation between subsequent days; the cultivation coefficients (kc) were obtained by the ratio between ETc and the reference evapotranspiration (ETo) obtained by the Penman-Montheit FAO-56 method. Biomass and evapotranspiration data were combined to determine water sensitivity. Diurnal fluxes of gas exchange (net photosynthesis rate, transpiration rate, stomatal conductance, internal and atmospheric carbon ratio, water use efficiency and leaf temperature) and Chl a fluorescence (Fv/Fm, ΦPSII, ETR, Fv’/Fm’, NPQ and qL) were evaluated. Water restriction caused reductions of 90.9 and 84.7% in the increase in height and diameter of seedlings subjected to 25% water replacement when compared to seedlings with 100% water replacement, while biomass accumulation reduced by 96.9%. The kc values increased throughout the seedling production cycle, ranging from 0.59 to 2.86. Maximum water sensitivity occurred at 50% water replacement, with Ky = 1.62. Maximum carbon assimilation rates occurred in the morning, ranging from 6.11 to 12.50 µmol m-2 s-1. Ipê-rosa seedlings regulate the physiology of growth, gas exchange, and Chl a fluorescence depending on the amount of water available, and only 25% of the water re-placement in the substrate allows the seedlings to survive.

In general, young plants in the establishment phase demonstrate sensitivity to changes in environmental conditions, especially regarding water availability. The effects of the seasonality of biophysical processes on plant physiology can trigger differential responses, even within the same region, making it necessary to conduct studies that characterize the physiological performance of the species at different spatial and temporal scales, making it possible to understand their needs and growth limits under water stress conditions. This paper aimed to evaluate the growth, gas exchange and Chl a fluorescence in ipê-rosa seedlings subjected to levels of water replacement (LWRs) of 100, 75, 50 and 25% in a greenhouse. The morphometric variables of plant height, diameter at stem height, numbers of leaves and leaflets, root length and volume, plant dry mass and leaf area were evaluated. The potential evapotranspiration of seedlings (ETc) was obtained using direct weighing, considering the water replacement of 100% of the mass variation between subsequent days as a reference; the cultivation coefficients (kc) were obtained using the ratio between ETc and the reference evapotranspiration (ETo) obtained by the Penman–Monteith FAO-56 method. Biomass and evapotranspiration data were combined to determine water sensitivity. Diurnal fluxes of gas exchange (net photosynthesis rate, transpiration rate, stomatal conductance, internal and atmospheric carbon ratio, water use efficiency and leaf temperature) and Chl a fluorescence (Fv/Fm, Φ_PSII, ETR, Fv′/Fm′, NPQ and qL) were evaluated. Water restriction caused reductions of 90.9 and 84.7% in the increase in height and diameter of seedlings subjected to 25% water replacement when compared to seedlings with 100% water replacement. In comparison, biomass accumulation was reduced by 96.9%. The kc values increased throughout the seedling production cycle, ranging from 0.59 to 2.86. Maximum water sensitivity occurred at 50% water replacement, with Ky = 1.62. Maximum carbon assimilation rates occurred in the morning, ranging from 6.11 to 12.50 µmol m⁻² s⁻¹. Ipê-rosa seedlings regulate the physiology of growth, gas exchange and Chl a fluorescence depending on the amount of water available, and only 25% of the water replacement in the substrate allows the seedlings to survive.

This work aimed to evaluate changes in gas exchanges and chlorophyll a fluorescence in fig plants due to the film formed on the leaf surface by Bordeaux mixture applied to control rust. The experiment was conducted in an orchard with 7-month-old fig trees of the cultivar Roxo de Valinhos, in April 2020. A completely randomized experimental design with four replications was used, consisting of two treatments (with and without application of Bordeaux mixture), evaluating leaves in three different parts of the branch (apical, middle, and basal) in five evaluations. The evaluated gas exchange parameters were: carbon, leaf temperature, transpiration, stomatal conductance, and photosynthesis. The evaluated chlorophyll fluorescence parameters were: maximum and effective quantum yield of the photosystem, electron transport rate, photochemical and non-photochemical quenching, and leaf area. The film formed by Bordeaux mixture application did not affect the photochemical phases of photosynthesis and chlorophyll a fluorescence. The leaf position on the branch affected internal CO2 concentration and net CO2 assimilation over time. Leaves in the middle part of the branch presented larger leaf areas than those in the apical and basal parts. Keywords: Ficus Carica L.; chlorophyll a; rust; leaf area. A película formada pela calda bordalesa na superfície foliar das figueiras interfere nos processos fotoquímicos? RESUMO: O objetivo desse trabalho foi avaliar se a camada formada pela solução da calda bordalesa na superfície foliar altera as características das trocas gasosas, bem como a Fluorescência da clorofila A, quando aplicada no combate a ferrugem. O delineamento experimental utilizado foi o inteiramente casualizado com 2 tratamentos (com e sem calda bordalesa) com folhas em 3 partes distintas do ramo da figueira (apical, mediana e basal), sendo feitas 5 avaliações, com 4 repetições, em um pomar de 7 meses de idade da cultivar Roxo de Valinhos, no mês de abril de 2020. As avaliações das trocas gasosas foram referentes a: variação do carbono, temperatura da folha, transpiração, condutância estomática e fotossíntese. As avaliações da fluorescência da clorofila A, foram referentes a: rendimento quântico máximo e efetivo do fotossistema, taxa de transporte de elétrons, dissipação fotoquímica e não fotoquímica e área foliar. A película formada pela aplicação da calda bordalesa não interferiu nas etapas fotoquímicas da fotossíntese e na fluorescência da clorofila A. A Concentração interna, e a assimilação líquida do CO2 foram influenciadas pela posição da folha no ramo ao longo do tempo. As folhas da parte mediana do ramo apresentam a maior área, em detrimento das partes apical e basal. Palavras-chave: Ficus Carica L.; clorofila A; ferrugem; área foliar.