ABSTRACT Moringa oleifera Lam. is an arboreal forest species of great economic potential, adapted to the climatic conditions of the Brazilian semi-arid region, whose multiplication is mainly by seeds. Rapid viability and vigor tests help in the choice of lots. Thus, the objective of this study was to assess the efficiency of the pH of exudate and primary root protrusion tests in the evaluation of viability and vigor, respectively. Two seed lots were initially evaluated for moisture content, germination, first count, germination speed index, seedling length, seedling dry mass and electrical conductivity. For the pH of exudate test, phenolphthalein (1%) and sodium carbonate (2 and 4 g L-1) solutions were prepared, with three soaking periods (1, 3 and 5 h) and three temperatures (25, 30 and 35 °C). Exudate solution in strong to light pink color indicated viable seeds, whereas very light pink color to colorless indicated non-viable seeds. The primary root protrusion test was performed under 25, 30 and 35 °C, evaluating the primary root protrusion of at least 2 mm, every 12 h until 196 h. The experimental design was completely randomized, with four replicates. pH of exudate test with 1 h of soaking at 25 or 30 °C with 2 g L-1 sodium carbonate solution was promising, but further studies are needed before it is indicated as routine use for the species. Primary root protrusion test is efficient and can be conducted at 35 °C with evaluation after 48 h. Lam potential semiarid semi arid region seeds Thus respectively content count index length conductivity 1% (1% ( L1 L prepared 1, (1 (25 °C. C . °C) nonviable non mm 19 randomized replicates L- promising

ABSTRACT Exposing seeds to agents that elicit tolerance to abiotic stress, such as phytohormones and organic acids, during hydration and dehydration cycles can determine their response to later stimuli, e.g. exposure to salt stress. The aim of this study was to evaluate the action of priming cycles with different eliciting agents of salt stress tolerance on seeds of the cowpea varieties Sempre Verde and Pingo de Ouro. The seeds were subjected to the following treatments: 0.0 mM NaCl (control); 100 mM NaCl (salt stress); salt stress + three seed-priming cycles (PC) in water; salt stress + PC in gibberellic acid; salt stress + PC in hydrogen peroxide; salt stress + PC in salicylic acid; salt stress + PC in ascorbic acid. The following variables were analysed: germination, growth, dry weight, salt tolerance index, total soluble sugars, total free amino acids and proline. Salt stress (100 mM NaCl) reduced germination, length and biomass accumulation in the Sempre Verde and Pingo de Ouro varieties. These showed the best response to the priming cycles with gibberellic and salicylic acids, which promoted greater germination potential, length and biomass under a salt stress of 100 mM NaCl, affording greater tolerance via osmotic regulation, especially in the Sempre Verde variety. stimuli eg e g e.g treatments 00 0 0. control (control) 10 stress) seedpriming seed (PC water acid peroxide analysed growth weight index sugars proline (10 potential regulation variety (control 1 (1 (

ABSTRACT. Invasive species threaten crops and ecosystems worldwide. Therefore, we sought to understand the relationship between the geographic distribution of species populations and the characteristics of seeds using new techniques such as seed image analysis, multivariate analysis, and machine learning. This study aimed to characterize Leucaena leucocephala (Lam.) de Wit. seeds from spatially dispersed populations using digital images and analyzed their implications for genetic studies. Seed size and shape descriptors were obtained using image analysis of the five populations. Several analyses were performed including descriptive statistics, principal components, Euclidean distance, Mantel correlation test, and supervised machine learning. This image analysis technique proved to be efficient in detecting biometric differences in L. leucocephala seeds from spatially dispersed populations. This method revealed that spatially dispersed L. leucocephala populations had different biometric seed patterns that can be used in studies of population genetic divergence. We observed that it is possible to identify the origin of the seeds from the biometric characters with 80.4% accuracy (Kappa statistic 0.755) when we applied the decision tree algorithm. Digital imaging analysis associated with machine learning is promising for discriminating forest tree populations, supporting management activities, and studying population genetic divergence. This technique contributes to the understanding of genotype-environment interactions and consequently identifies the ability of an invasive species to spread in a new area, making it possible to track and monitor the flow of seeds between populations and other sites. ABSTRACT worldwide Therefore Lam. Lam (Lam. Wit statistics components distance test L divergence 804 80 4 80.4 Kappa 0.755 0755 0 755 algorithm activities genotypeenvironment genotype environment area sites (Lam 8 80. 0.75 075 75 0.7 07 7 0.

ABSTRACT This study investigated the effectiveness of using the X-ray technique to assess the viability of papaya seeds. The X-ray images were performed in eight replicates of 25 seeds, placed on transparent acrylic plates on double-sided adhesive tape, previously identified, and then submitted to radiation in X-ray equipment "HP Faxitron". After exposure to X-ray radiation, the seeds were submitted to the germination test in rolls of germitest paper and kept in a germination chamber at 20-30 °C for 30 days. Seedlings were photographed and evaluated as normal seedlings, abnormal and non-germinated seeds. Afterward, the X-ray images and the seedlings from the same seeds were visually compared, and the X-ray images clearly showed seeds with and without internal filling. All abnormal seedlings were full seeds; therefore, X-ray images were not able to separate normal and abnormal. A 100% accuracy was verified by comparing the X-ray images and their respective seedlings, full seeds originated normal or abnormal seedlings, and empty seeds corresponded to non-germinated seeds. Therefore, using X-ray images is a promising technique to identify the viability of papaya seeds. The automated analysis of X-ray images is a simple, fast, and efficient technique to provide information on seed viability and generate parameters related to their germination capacity. Xray X ray 2 doublesided double sided tape identified HP Faxitron. Faxitron . Faxitron" 2030 20 20-3 C 3 days nongerminated non germinated Afterward compared filling therefore 100 Therefore simple fast capacity 203 20- 10 1

ABSTRACT: The tetrazolium test quickly assesses seed viability, the efficiency of which depends on methodological adjustments for each species. Therefore, the objective was to evaluate the viability of Anadenanthera colubrina seeds using this test. The seeds were aged for 12 h and 24 h to obtain differences in physiological quality. Initial quality was assessed by the following tests: germination, emergence, GSI and ESI, and MGT and MET. For the tetrazolium test, a completely randomized experimental design was used in a 3 × 9 factorial arrangement consisting of three accelerated aging (AA) conditions (0, 12, and 24 h of AA) and nine combinations between concentrations of tetrazolium salt and immersion time in this salt (0.075% / 4 h, 0.075% / 6h, 0.075% / 8h, 0.1% / 4 h, 0.1% / 6 h, 0.1% / 8 h, 0.5% / 4 h, 0.5% / 6 h, and 0.5% / 8 h), with four replications of 25 seeds, evaluated at temperatures of 35 °C and 40 °C. The seeds were classified as viable and vigorous, viable and not vigorous, and inviable. The tetrazolium test was effective for estimating the viability of A. colubrina seeds. To make this estimation, the seeds should be chipped in the region opposite the micropyle, then pre-moistened in water for 10 h, followed by removal of the seed coat and immersion in a 0.1% tetrazolium solution for 4 h at 35 °C. Under these conditions, the tetrazolium test successfully identified differences in the physiological quality of unaged seeds and seeds aged for 12 h and 24 h. ABSTRACT species Therefore 1 2 tests germination emergence ESI MET AA (AA 0, 0 (0 0075 075 (0.075 0.075 6h 8h 01 0.1 05 5 0.5 , h) C vigorous inviable A estimation micropyle premoistened pre moistened ( 007 07 (0.07 0.07 0. 00 (0.0 0.0 (0.

RESUMO: O teste de tetrazólio avalia de forma rápida a viabilidade das sementes, cuja eficiência depende de ajustes metodológicos para cada espécie. Com isso, objetivou-se avaliar a viabilidade em sementes de Anadenanthera colubrina por meio desse teste. As sementes foram envelhecidas por 12 e 24 horas para obter diferenças na qualidade fisiológica. A qualidade inicial foi avaliada pelos testes de germinação; emergência; IVG e IVE; TMG e TME. Para o teste de tetrazólio utilizou-se o delineamento experimental inteiramente casualizado em esquema fatorial 3 x 9 e os tratamentos constaram: três condições de envelhecimento acelerado - EA (0, 12 e 24 h de EA) e nove combinações entre concentrações e tempo de imersão no sal de tetrazólio: 0,075%/4 h; 0,075%/6 h; 0,075%/8 h; 0,1%/4 h; 0,1%/6 h; 0,1%/8 h; 0,5%/4 h; 0,5%/6 h; 0,5%/8 h, com quatro repetições de 25 sementes, avaliados sob as temperaturas de 35 e 40 °C. As sementes foram classificadas em viáveis e vigorosas, viáveis e não vigorosas e inviáveis. O teste de tetrazólio foi eficiente para estimar a viabilidade de sementes de A. colubrina. Para isso, deve-se realizar o desponte na região oposta a micrópila, com pré-umedecimento em água por 10 h, seguido da remoção do tegumento e imersão na solução de tetrazólio a 0,1%, por 4 h, a 35 °C. Nessa condição, o teste de tetrazólio foi eficiente para identificar diferenças na qualidade fisiológica de sementes não envelhecidas e envelhecidas por 12 e 24 horas. RESUMO espécie isso objetivouse objetivou se 1 2 germinação emergência IVE TME utilizouse utilizou constaram 0, 0 (0 00754 075 0,075%/ 00756 6 00758 8 014 0,1%/ 016 018 054 5 0,5%/ 056 058 C °C inviáveis devese deve micrópila préumedecimento pré umedecimento 01 0,1% condição ( 0075 07 0,075% 05 0,5% 0,1 007 0,075 0,5 00 0,07 0,0

ABSTRACT Among the main problems that compromise the development of forest species are water and salt stresses, especially in the early stages of development, when seedlings are more sensitive. Thus, the objective of this study was to evaluate the morphophysiological and biochemical changes in Enterolobium contortisiliquum seedlings subjected to abiotic stresses. The experimental design was randomized complete blocks (RCB), composed of five treatments, with four replicates, and the experimental plot consisted of twenty plants. From the 31st day after sowing, when the seedlings reached approximately 15 cm in height, they began to receive the treatments, which consisted of different levels of electrical conductivity of irrigation water (0.3; 2; 4; 6; 8 dS m-1) for salt stress and periods of water restriction (0; 4; 8; 12 and 16 days without irrigation) for water stress. The traits evaluated were: plant height, root length, stem diameter, number of leaves, leaf area, total dry matter, Dickson quality index, height/shoot dry matter ratio, total soluble sugars, starch, total amino acids and proline. An increase in the electrical conductivity of irrigation water and days without irrigation compromised the development of E. contortisiliquum seedlings, which was intensified from 2 dS m-1 and four days without irrigation for salt and water stresses, respectively. The mechanism of survival of E. contortisiliquum to abiotic stresses involves reduction in the growth and quality of seedlings, with activation of biochemical defense mechanisms of the species. sensitive Thus RCB, RCB , (RCB) treatments replicates plants st sowing 1 height 0.3 03 0 3 (0.3 4 6 m1 m (0 were length diameter leaves area index heightshoot shoot ratio sugars starch proline E m- respectively (RCB 0. (0. (

ABSTRACT The objective was to verify if the primary root emission can be recommended as a vigor test for soybean seeds. For this, five lots of varieties ANTA 82, NA7337 and BRS1074IPRO were evaluated by first count, germination, emergence, emergence speed index and tetrazolium tests. In the root protrusion test at 20, 25 and 30 ºC, two evaluation criteria were adopted: primary root emission precocity index (PREPI) and percentage of seeds that emitted the primary root (PRE). The seeds counted were those with a primary root equal to or greater than 2 mm, every 12 h from the installation of the test until 120 h. The design was completely randomized and means were compared, within each evaluation time, using the Scott-Knott test at 5% probability. Pearson’s linear correlation was performed for PREPI and PRE with emergence. PREPI was not considered efficient. For the PRE, at 20 ºC, there was a correlation at 72 h, for the three varieties. At 25 ºC there was a correlation for a period of 36 h for ANTA 82 and NA7337 and 60 h for BRS1074IPRO. At 30 ºC there was a correlation in the time of 36 h for the three cultivars. Considering that speed in obtaining results is important in vigor tests, it is concluded that primary root emission for 36 h after installing the test at 30 ºC is recommended as a vigor test in the quality control of soybean seeds. this NA NA733 BRSIPRO BRS IPRO count germination tests 3 adopted (PREPI PRE. . (PRE) mm 1 compared ScottKnott Scott Knott 5 probability Pearsons Pearson s efficient 7 8 6 cultivars NA73 (PRE NA7

ABSTRACT. The scarcity of surface water has led to the use of underground sources as an alternative for crop irrigation by farmers in semi-arid regions. However, these water sources generally have high salinity, which prevents agricultural production. The objective of this study was to determine the effects of pre-germination treatments with plant growth regulators and bioactivators on melon seeds to attenuate salt stress caused by irrigation water during germination and seedling development. Two trials were carried out separately with the hybrids, Goldex and Grand Prix. The design was completely randomized in a 4 × 3 factorial scheme (four seed treatments and three dilutions of irrigation water). Seeds were treated with salicylic acid and gibberellic acid and the insecticide, thiamethoxam, in addition to the control. Local supply water, artesian well groundwater, and dilution of these waters at a 1:1 ratio were employed for irrigation. Fourteen days after sowing, morphological and physiological analyses were performed, and the material was collected for biochemical determination. The use of saline well water affected the initial development of melon seedlings of the Goldex and Grand Prix hybrids. Pre-germination treatment of Goldex hybrid seeds with gibberellic acid was inefficient at mitigating salt stress. However, the effects of irrigation water salinity on Grand Prix melon seeds pretreated with salicylic acid and thiamethoxam were attenuated. ABSTRACT semiarid semi arid regions However production pregermination pre hybrids four water. . water) insecticide control groundwater 11 1 1: sowing performed determination Pregermination Pre attenuated

ABSTRACT The tetrazolium test is a fast and effective method to determine seed viability. In this context, the objective was to adapt the methodology of the tetrazolium test, in relation to preconditioning, to determine the viability (Eugenia stipitata McVaugh ssp. sororia McVaugh) under different times of immersion in solution and seed size. The seeds of E. stipitata ssp. sororia need to go through preconditioning, fractionation being an indispensable technique to be performed before immersion of the seed in the tetrazolium solution, as it allows the contact of the salt with the tissue to be analyzed, which, when feasible, staining occurs (formation of the substance triphenyl-formazan). The immersion time of 26 hours in the tetrazolium solution (1% at 26 °C) is indicated for determining the viability of E. stipitata ssp. sororia seeds, regardless of the seed mass classes used. context preconditioning Eugenia ssp size E analyzed which feasible formation triphenylformazan. triphenylformazan triphenyl formazan . triphenyl-formazan) 2 1% 1 (1 °C C used triphenyl-formazan (

RESUMO O teste de tetrazólio é um método rápido e eficaz para obter a viabilidade de sementes. Neste contexto, objetivou-se adequar a metodologia do teste de tetrazólio, em relação ao pré-condicionamento, para determinar a viabilidade de sementes de araçá-boi (Eugenia stipitata McVaugh ssp. sororia McVaugh) sob diferente tempo de imersão em solução e tamanho de semente. As sementes de E. stipitata ssp. sororia necessitam-se passar pelo pré-condicionamento, sendo o fracionamento uma técnica indispensável de ser realizada antes da imersão da semente na solução de tetrazólio, pois permite o contato do sal com o tecido a ser analisado, que quando viável ocorre a coloração (formação da substância trifenil-formazan). O tempo de imersão de 26 horas na solução de tetrazólio (1% a 26 °C) é indicado na determinação da viabilidade de sementes de Eugenia stipitata ssp. sororia. independentemente da classe de semente utilizada. contexto objetivouse objetivou se précondicionamento, précondicionamento pré condicionamento, condicionamento pré-condicionamento araçáboi araçá boi ssp E necessitamse necessitam analisado formação trifenilformazan. trifenilformazan trifenil formazan . trifenil-formazan) 2 1% 1 (1 °C C utilizada trifenil-formazan (

Abstract: Melon is one of the most consumed cucurbits and commercially significant cucurbits in the world. It is planted predominantly through seedlings, and seed quality is essential in this process. Among the rapid tests used in seed analysis, the pH testing of exudate has shown promise for several cultivated species. Thus, this study aimed to verify the viability of melon (Cucumis melo L.) seeds through the pH testing of exudate. For this, seeds of the hybrids Premier and Supreme (three lots each) were subjected to germination and vigor tests (first germination count, tetrazolium, accelerated aging, emergence speed index, and emergence). The pH testing of exudate was evaluated using phenolphthalein and sodium carbonate solutions. The results indicated the possibility of classifying the lots into three quality levels for both hybrids, similar to most tests used to assess initial quality. Therefore, the pH testing of exudate was effective in determining the viability of lots of melon seeds and can be conducted with a soaking period of 120 minutes at 25 or 30 °C. Abstract world seedlings process analysis species Thus Cucumis L. L each first count tetrazolium aging index emergence. . emergence) solutions Therefore 12 2 3 C °C 1

Resumo: O meloeiro é uma das cucurbitáceas mais consumidas e de maior interesse comercial do mundo. Seu plantio é realizado predominantemente por meio de mudas, sendo a qualidade das sementes fundamental neste processo. Dentre os testes rápidos utilizados na análise de sementes, o pH do exsudato tem se mostrado promissor para várias espécies cultivadas. Com isso, objetivou-se verificar a viabilidade de sementes de melão (Cucumis melo L.) por meio do teste de pH do exsudato. Para isso, sementes dos híbridos Premier e Supreme (três lotes de cada) foram submetidas aos testes de germinação e vigor (primeira contagem de germinação, tetrazólio, envelhecimento acelerado, índice de velocidade de emergência e emergência). O teste de pH de exsudato foi avaliado com a utilização de soluções de fenolftaleína e carbonato de sódio. Os resultados indicaram que para ambos os híbridos foi possível classificar os lotes em três níveis de qualidade, semelhantes a maioria dos testes utilizados na avaliação da qualidade inicial. Com isso, o teste de pH do exsudato mostrou-se eficaz para determinar a viabilidade de lotes de sementes de melão, podendo ser conduzido com período de embebição de 120 minutos a 25 ou 30 °C. Resumo mundo mudas processo cultivadas isso objetivouse objetivou Cucumis L. L cada primeira tetrazólio acelerado emergência. . emergência) sódio inicial mostrouse mostrou 12 2 3 C °C 1

RESUMO O feijão-caupi sofre perdas de produção significativas quando submetido ao estresse salino, porém esta ocorrência é variável entre os genótipos. Com isso, objetivou-se avaliar a fenologia e a produção de sementes crioulas de feijão-caupi irrigadas com água salina. A pesquisa foi conduzida em duas etapas, a primeira aconteceu em casa de vegetação para avaliar a fenologia e a produção dos genótipos de feijão-caupi. A segunda foi realizada em laboratório para avaliar a viabilidade e o vigor das sementes produzidas na primeira etapa. Os tratamentos constaram da combinação de dois níveis de salinidade da água de irrigação (0,5 e 4,5 dS m-1) e 14 variedades crioulas de feijão-caupi (Boquinha, Ceará, Costela-de-vaca, Lisão, Canário, Pingo-de-ouro, Roxão, Branco, Canapum-branco, Canapum-miúdo, Baêta, Coruja, Paulistinha e Sempre-verde) adquiridas junto aos agricultores tradicionais da região Oeste do Rio Grande do Norte, Brasil. As variedades Canário, Baêta e Coruja resultaram com maior número de flores por planta e floração mais precoce. A salinidade diminuiu o número de flores por planta, aumentou o seu abortamento em todas as variedades crioulas e reduziu a produção para as precoces Branco, Canapum-miúdo, Baêta e Coruja. O cultivo irrigado com água salina não afetou a viabilidade das sementes da segunda geração do feijão-caupi, mas diminuiu o vigor das sementes das variedades Lisão, Pingo-de-ouro, Roxão, Branco, Canapum-branco, Canapum-miúdo, Baêta e Coruja. As variedades crioulas Boquinha, Ceará, Costela-de-vaca, Canário, Paulistinha e Sempre-verde foram indicadas para a produção de sementes de feijão-caupi irrigado com água salina.

ABSTRACT Cowpea suffers significant production losses when subjected to salt stress, but the response varies among genotypes. The objective of this study was to evaluate the phenology and production of traditional cowpea seeds under saline water irrigation. The experiment was conducted in two stages, the first one in a greenhouse to evaluate the phenology and production of cowpea genotypes and the second one in the laboratory to assess the viability and vigor of the seeds produced in the first stage. The treatments resulted from the combination of two salinity levels of the irrigation water (0.5 and 4.5 dS m-1) and 14 traditional cowpea varieties (Boquinha, Ceará, Costela-de-vaca, Lisão, Canário, Pingo-de-ouro, Roxão, Branco, Canapum-branco, Canapum-miúdo, Baêta, Coruja, Paulistinha, and Sempre-verde) acquired from traditional farmers in the western region of Rio Grande do Norte, Brazil. Canário, Baêta, and Coruja varieties have a higher number of flowers per plant and earlier flowering. Salinity reduced the number of flowers per plant, increased abortion in all traditional varieties and reduced production in the early varieties Branco, Canapum-miúdo, Baêta, and Coruja. Cultivation under saline water irrigation did not affect the viability of the seeds from the second generation of cowpea, but reduced the vigor of the seeds of the varieties Lisão, Pingo-de-ouro, Roxão, Branco, Canapum-branco, Canapum-miúdo, Baêta and Coruja. The traditional varieties Boquinha, Ceará, Costela-de-vaca, Canário, Paulistinha and Sempre-verde are indicated for the production of cowpea seeds under irrigation with saline water.

RESUMO O pré-tratamento de sementes resulta em emergência de plântulas mais rápida e estande uniforme, principalmente, quando sob estresse. Sendo assim, objetivou-se avaliar a ação de reguladores vegetais como atenuantes de estresse durante a germinação e desenvolvimento inicial de plântulas de abóbora, cv. Baiana Tropical, irrigadas com água salina. Para isso, estabeleceu-se o delineamento inteiramente casualizado, em esquema fatorial 4 x 3, em quatro repetições. Os tratamentos foram constituídos de quatro tipos de água (A1 – 100% água de abastecimento; A2 – 100% efluente de piscicultura; A3 – 100% água de poço artesiano; A4 - mistura de 50% efluente de piscicultura + 50% água de poço artesiano) e três tratamentos de sementes (controle, ácidos salicílico e giberélico). As variáveis mensuradas foram germinação, primeira contagem de germinação, comprimento da parte aérea e raiz, massa seca da parte aérea e raiz, açúcares solúveis totais, aminoácidos totais e prolina. Os dados foram submetidos a análise de variância e teste de Scott-Knott. As plântulas de abóbora realizaram ajustamento osmótico em condições salinas da água A4. Além disso, o tratamento de sementes de abóbora com reguladores vegetais (ácidos giberélico e salicílico) beneficia a germinação e o desenvolvimento inicial de plântulas sob condições de estresse salino.

ABSTRACT Pretreatment of seeds results in faster emergence of seedlings and uniform stand, especially under stress. Thus, the objective was to evaluate the action of plant regulators as stress attenuators during germination and initial development of pumpkin seedlings, cv. ‘Baiana Tropical’, irrigated with saline water. For this, a completely randomized design was established, in a 4 x 3 factorial scheme, with four replications. Treatments consisted of four types of water (W1 - 100% supply water; W2 - 100% fish farming effluent; W3 - 100% artesian well water; W4 - mixture of 50% fish farming effluent + 50% artesian well water) and three seed treatments (control, salicylic acid and gibberellic acid). The variables measured were germination, first germination count, shoot and root length, shoot and root dry mass, total soluble sugars, total amino acids and proline. The data were subjected to analysis of variance and Scott-Knott test. Pumpkin seedlings performed osmotic adjustment under saline conditions of W4 water. In addition, the treatment of pumpkin seeds with plant regulators (gibberellic and salicylic acids) favors the germination and initial development of seedlings under conditions of salt stress.

RESUMO O sorgo é uma importante cultura que pode absorver e acumular Si em abundância, melhorando a tolerância do tecido aos estress hidríco e salino e reduzindo a absorção de sódio. Objetivou-se verificar a indução de resistência na germinação e no crescimento de mudas de sementes de sorgo ao sal e ao estresse hídrico durante a germinação devido ao tratamento com silício.Foram realizados dois experimentos com sementes de duas cultivares de sorgo (EA03 e EA955) em soluções de silicato de potássio na concentração de 0, 0,3 , 0,6, 0,9 e 1,2 g L-1, no primeiro experimento e as sementes foram submetidas ao estresse hídrico utilizando PEG 6000 (0, -0,2, -0,4, -0,6 e -0,8 MPa) no segundo experimento foram submetidas ao estresse salino usando e NaCl (0, 75, 150 e 225 mM). Foram analisados a germinação, primeira contagem de germinação, comprimento da parte aérea e raiz, proporção parte aérea/raiz e massa seca de plântulas. Os genótipos estudados apresentaram comportamento semelhante quando tratados com silicato de potássio. A presença do silício no tratamento de sementes quando expostas ao estresse salino não tem efeito sobre a germinação, mas atenua a salinidade relacionada ao crescimento das mudas. O silício atenua os efeitos do estresse hídrico nas sementes de sorgo, mantendo a germinação até o potencial de -0,6 Mpa, e proporcionando melhor desenvolvimento radicular. No entanto, o tratamento com silicato de potássio não evita os danos causados pelos altos níveis de estresse hídrico e salino, apenas atenua seus efeitos, assim mais estudos são necessários para esclarecer melhor os efeitos do Si nas sementes.

ABSTRACT Sorghum is an important crop that can absorb and accumulate abundant Si ranging, improving tissue tolerance to the water and salt stress and reducing sodium absorption. T hus, the objective was to verify the induction of resistance in germination and seedling growth of sorghum seeds to salt and water stress during germination due to treatment with silicon. Two experiments were carried out with seeds of two sorghum cultivars (EA03 and EA955) were solution of potassium silicate solutions at concentrations of 0, 0.3, 0.6, 0.9 and 1.2 g L-1, in the first experiment and seeds were submitted to water stress using PEG 6000 (0, -0.2, -0.4, -0.6 and -0.8 MPa) in the second experiment were submitted to salt stress using NaCl (0, 75, 150 and 225 mM). Were analysed, germination, first germination count, shoot and root length, shoot to root ratio and seedling dry weight. The studied genotypes showed similar behavior when treated with potassium silicate. The presence of silicon in the treatment of seeds when exposed to salt stress has no effect on germination, but attenuates salinity damage related to seedling growth. Silicon attenuates the effects of water stress on sorghum seeds, by maintaining germination up to the potential of -0.6 Mpa, and providing better root development. However, the treatment with potassium silicate does not prevent the damage caused by high levels of water and salt stress, only attenuating its effects, thus, more studies are needed to better clarify the effects of Si on seeds.

RESUMO A adoção de tecnologias que permitam a atenuação de estresses ambientais, como o uso de reguladores no tratamento de sementes, é uma alternativa para cultivos em regiões com temperaturas elevadas. Objetivou-se avaliar a mitigação do estresse térmico na germinação e desenvolvimento inicial de plântulas de cenoura, por meio de reguladores de crescimento vegetal. O estudo foi dividido em três ensaios, utilizando-se temperaturas de 25, 30 e 35 °C. Empregou-se esquema fatorial 5 x 3, sendo cinco cultivares de cenoura (Alvorada, Brasília, BRS Esplanada, Tellus e Tropical) e dois produtos (Stimulate® e tiametoxam), além do controle (sementes não tratadas). Avaliaram-se as seguintes variáveis: germinação, primeira contagem de germinação, comprimento e massa seca de plântula. Quando as cultivares tiveram as sementes tratadas com os reguladores de crescimento vegetal a 25 °C, Tellus apresentou germinação 28 % superior ao controle, enquanto, a 30 °C, BRS Esplanada e Tellus apresentaram germinação duas vezes maior que o controle e expressaram melhor vigor, em detrimento da Alvorada, Brasília e Tropical. De modo geral, o tiametoxam promoveu incrementos no desenvolvimento inicial de plântulas de cenoura aos 25 e 30 °C. No entanto, a germinação das cultivares de cenoura foi interrompida a 35 °C.

ABSTRACT The adoption of technologies that allow the mitigation of environmental stresses, such as the use of regulators in seed treatment, is an alternative for crops in high temperatures regions. This study aimed to assess the heat stress mitigation on the germination and initial development of carrot seedlings using plant growth regulators. The study was divided into three experiments performed at the temperatures of 25, 30 and 35 °C. A 5 × 3 factorial arrangement was used, with fve carrot cultivars (Alvorada, Brasília, BRS Esplanada, Tellus and Tropical) and two products (Stimulate® and thiamethoxam), in addition to the control (untreated seeds). The following variables were evaluated: germination, first germination count, seedling length and dry mass. When the cultivars had their seeds treated with the plant growth regulators at 25 °C, the germination for the Tellus cultivar was 28 % higher than for the control, while, at 30 °C, the seed germination for BRS Esplanada and Tellus was twice as high as for the control, and showed a higher vigor than that of Alvorada, Brasília and Tropical. Overall, the thiamethoxam promoted increments at the initial development of carrot seedlings at 25 and 30 °C. However, the germination of the carrot cultivars was disrupted at 35 °C.

RESUMO Pitaya (Hylocereus undatus e H. costataricensis) encontra-se no grupo de frutas exóticas e seu cultivo no Brasil está em expansão, sobretudo na região semiárida do Nordeste. Nessa região os problemas de quantidade e qualidade hídrica normalmente ocasionam estresses ambientais limitando à sobrevivência das plantas, principalmente durante a germinação e estabelecimento de plântulas. Sendo assim, objetivou-se verifi car a ação mitigadora de tratamentos pré-germinativos em sementes de pitaya sob estresse salino. O experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial 2 × 6, correspondente a duas espécies de pitayas H. undatus e H. costatariciensis e seis tratamentos pré-germinativos (T1 = 0,0 MPa (controle); T2 = estresse salino (-0,4 MPa); T3 = hidrocondicionamento + estresse salino; T4 = ácido giberélico + estresse salino; T5 = ácido salicílico + estresse salino; T6 = tiametoxan + estresse salino). Após 20 dias de semeadura, analisou-se a germinação, índice de velocidade de germinação, comprimentos de partes aérea e raiz primária, massa seca total, açúcares solúveis totais e aminoácidos livres totais. H. costaricensis mostrou-se mais tolerante à salinidade que H. undatus. O ácido salicílico estimulou a germinação e o crescimento de H. undatus, além de aumentar o teor de açúcares solúveis em H. costaricensis. O hidrocondicionamento das sementes atenuou o estresse salino durante a germinação de H. undatus e favoreceu o ganho de massa seca. O ácido giberélico estimulou a germinação de H. undatus e o crescimento de plântulas desta e de H. costaricensis, além disso aumentou os níveis de açúcares solúveis em H. undatus.

ABSTRACT Pitaya (Hylocereus undatus and H. costaricensis) is found in the group of exotic fruits and its cultivation in Brazil is expanding, especially in the semi-arid region of the Northeast. In this region, the problems of water quantity and quality usually cause environmental stresses which limit the survival of plants, especially during germination and seedling establishment. Thus, the objective was to evaluate the mitigating action of pre-germination treatments in pitaya seeds under salt stress. The experiment was conducted in a completely randomized design, in a 2 × 6 factorial scheme, corresponding to two species of pitaya (H. undatus and H. costaricensis) and six pre-germination treatments (T1 = 0.0 MPa (control); T2 = salt stress (-0.4 MPa); T3 = hydropriming + salt stress; T4 = gibberellic acid + salt stress; T5 = salicylic acid + salt stress; T6 = thiamethoxam + salt stress). After 20 days of sowing, germination, germination speed index, shoot length, primary root length, total dry mass, total soluble sugars and total free amino acids were analyzed. H. costaricensis was more tolerant to salinity than H. undatus. Salicylic acid stimulated the germination and growth of H. undatus, besides increasing the soluble sugar content in H. costaricensis. Seed hydropriming attenuated salt stress during germination of H. undatus and favored dry mass gain. Gibberellic acid stimulated the germination of H. undatus and the growth of H. undatus and H. costaricensis seedlings, in addition to increasing the levels of soluble sugars in H. undatus.