Adaptation of the tetrazolium test for assessment of sunflower seed viability and vigor

O objetivo deste trabalho foi avaliar metodologias para realização do teste de tetrazólio, na avaliação da viabilidade e do vigor de sementes de girassol, e estabelecer classes de qualidade para interpretação do teste. Foram avaliadas diferentes formas de extração do pericarpo e do tegumento das sementes, além do pré‑condicionamento em água por 16 e 18 horas (25°C) e da coloração em solução de tetrazólio (30ºC), nas concentrações de 0,1 e 0,5%, por 2, 3 e 4 horas; e de 1,0%, por 1, 2 e 3 horas. Após a definição da metodologia mais adequada para realização do teste, classes de vigor foram estabelecidas de acordo com a emergência das plântulas no campo. Foram identificadas cinco classes, as quais apresentaram correlação perfeita com a emergência. Para avaliar a viabilidade das sementes de girassol, o pericarpo e o tegumento devem ser retirados após corte longitudinal com até 1/3 do comprimento da semente, o pré‑condicionamento deve ser feito pela imersão em água por 16 horas, e a coloração deve ser realizada em solução de tetrazólio a 0,1%, durante 3 horas.The objective of this work was to evaluate methodologies for performing the tetrazolium test in the evaluation of the viability and vigor of sunflower seeds, and to establish seed quality classes for test interpretation. Different methodologies were evaluated for extracting the pericarp and seed coat, besides water priming for 16 and 18 hours (25°C), and staining with tetrazolium solution (30ºC) at the concentrations of 0.1 and 0.5%, for 2, 3, and 4 hours; and of 1.0%, for 1, 2, and 3 hours. After the definition of the most adequate methodology for performing the test, vigor classes were established according to seedling emergence on field. Five vigor classes were established, which had perfect correlation with seedling emergence. For the viability assessment of sunflower seeds, the pericarp and the seed coat should be removed after a lengthwise cut of up to 1/3 seed length, water priming should be carried out for 16 hours, and staining should be done with tetrazolium solution at 0.1%, during 3 hours

An alternative procedure in the tetrazolium test for soybean seed

O objetivo deste estudo foi desenvolver um procedimento alternativo para redução do período de precondicionamento de sementes de soja no teste de tetrazólio. Foram empregados dois tamanhos de sementes de doze cultivares de soja [Glycine max (L.) Merrill], produzidas em Londrina, PR, em 1993 e 1994. Os tratamentos utilizados foram dois períodos de embebição (quatro horas e seis horas) na temperatura de 41oC, tendo como testemunha o procedimento-padrão de dezesseis horas, a 25oC. Os parâmetros usados para avaliar os tratamentos foram o vigor [TZ (1-3)], a viabilidade [TZ (1-5)], a deterioração por umidade [TZ (6-8)], o dano mecânico [TZ (6-8)], as lesões por percevejos [TZ (6-8)] e o teor de água das sementes. O período de seis horas a 41oC propiciou condições adequadas de coloração das sementes, o que permitiu a avaliação e interpretação do vigor, da viabilidade, da deterioração por umidade, do dano mecânico e das lesões por percevejos. Usando-se seis horas de precondicionamento a 41oC, há uma redução de dez horas na execução do teste, em comparação ao procedimento atualmente recomendado, sem compremeter a precisão requerida.The aim of this work was to develop an alternative procedure for reducing the soybean seed preconditioning in the tetrazolium test. Two imbibition periods (four and six hours) at 41oC were tested and compared to the traditionally recommended period for preconditioning of 16 hours at 25 ºC. Seeds of twelve cultivars were used, and classified into two sizes. The parameters used were: vigor [TZ (1-3)]; viability [TZ (1-5)]; weathering [TZ (6-8)]; mechanical damage [TZ (6-8)]; stink bug damage [TZ (6-8)]; and seed moisture content. The staining pattern developed on the seeds after a preconditioning period of six hours at 41 ºC is suitable for the evaluation of the quality of soybean seeds by the tetrazolium test. Seed preconditioning procedures for the tetrazolium test evaluated in this experiment were not affected by the size of soybean seeds; the 6 hour/41oC treatment reduces the period of preconditioning by ten hours when compared to the recommended procedures of 16 hours at 25ºC. To sum up, in the tetrazolium test for soybean seeds, the preconditioning conditions of 6 hour/41oC can be used successfully, without impairing the precision required by the test

PRE-GERMINATION TREATMENT OF CARROT SEEDS WITH BIOACTIVATOR

Carrot is a vegetable with an important socio-economic role, both due to the employment of labor and high commercialization. To optimize the establishment of this crop in fields, seeds with rapid and uniform germination are essential. Therefore, various seed treatment techniques have been used to enable and enhance the germination percentage and optimize the vigor of the seeds. In continuation with this, the objective of this study was to evaluate the effects of thiamethoxam on the physiological performance of carrot seeds during germination and initial development of seedlings. The experimental design was a completely randomized design in a 5 × 4 factorial scheme, with five carrot cultivars and four doses of thiamethoxam (0, 0.4, 0.8, and 1.2 mL). Parameters such as germination, first germination count, seedling length, and dry mass were evaluated. In addition, biochemical analyses of total sugars, total amino acids, and proline content were performed. In general, the treatment of carrot seeds with thiamethoxam positively influenced the germination of the seeds of the cultivars studied. However, thiamethoxam doses of 0.4 and 0.8 mL had no positive effect on the seedling development of the Tropical cultivar. The thiamethoxam dose of 1.2 mL was beneficial to the development of seedlings and accumulation of metabolites in the Alvorada cultivar.A cenoura é uma hortaliça com papel socioeconômico importante, tanto pelo elevado emprego de mão-de-obra, quanto por sua alta comercialização. Para otimizar o estabelecimento dessa cultura em campo se torna imprescindível sementes com germinação rápida e uniforme. Por isso, tem-se utilizado o tratamento de sementes como técnica para viabilizar o desempenho germinativo e expressão de vigor. Desse modo, objetivou-se avaliar os efeitos do tiametoxam no desempenho fisiológico de sementes de cenoura durante a germinação e desenvolvimento inicial de plântulas. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 5 x 4, sendo cinco cultivares de cenoura e quatro dosagens de tiametoxam (0; 0,4; 0,8 e 1,2 mL). Avaliaram-se a germinação, primeira contagem de germinação, comprimento e massa seca de plântula, além de análises bioquímicas do conteúdo de açúcares totais, aminoácidos totais e prolina. Os dados coletados foram submetidos à análise de variância (p ≤ 0,05) seguido do teste de Tukey e análise de regressão. O tratamento de sementes de cenoura com tiametoxam, no geral, influenciou positivamente a germinação das sementes das cultivares estudadas. No entanto, as dosagens de 0,4 e 0,8 mL de tiametoxam para cultivar Tropical não houve influência positivamente o desenvolvimento de plântulas. A dose de 1,2 mL do bioativador, para a cultivar Alvorada, foi benéfico ao desenvolvimento de plântulas e acúmulo de metabólitos

Pre-germination treatments with plant growth regulators and bioactivators attenuate salt stress in melon: effects on germination and seedling development

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

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio