Salinity problems are increasing in the semi-arid regions of northeastern Brazil. Thus, detailed studies of the region's cultured crops, primarily salt-tolerant species, are important. Therefore, the aim of the present study was to evaluate the salt stress tolerance of lima bean (Phaseolus lunatus L.) seeds at different temperatures. This study was conducted in the Seed Analysis Laboratory, Agricultural Sciences Center, Federal University of Paraíba (Areia, PB, Brazil) by using seeds of four lima bean cultivars (Branca, Orelha de Vó, Rosinha, and Roxinha) in a randomized experimental design. Sodium chloride (NaCl) was used as a solute for salt-stress simulation at the following concentrations: 0.0 (control), 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 dS m -1 ; temperatures were maintained constant at 25°C, 30°C, and 35°C. Germination and vigor tests were performed to evaluate the treatment effects (first count, germination rate index, seedling length, and dry matter). Germination rate of lima bean seeds increased in salt concentrations up to 9 dS m -1 , and seeds of Roxinha cultivar exhibited the highest salinity tolerance. The development of lima bean cultivar seedlings was negatively affected at 35°C under high-salinity conditions.
Platymiscium floribundum Vog., uma espécie florestal pertencente à família Fabaceae, apresenta grande potencial para exploração econômica e pode ser utilizada tanto no paisagismo como em reflorestamentos, na recuperação de áreas degradadas e de preservação permanente. Diante de sua importância, o trabalho teve como objetivo estudar a influência da luz e temperaturas na germinação de sementes de Platymiscium floribundum. Avaliou-se a germinação e vigor das sementes sob temperaturas de 25 e 30ºC constantes e 20-30ºC alternada em diferentes regimes de luz: branca (LB), verde (LV), vermelha-distante (LVD), vermelha (LV) e ausência de luz (A). O delineamento experimental foi inteiramente ao acaso, em esquema fatorial 3 x 5, com quatro repetições de 25 sementes. As variáveis analisadas foram: germinação, primeira contagem de germinação, índice de velocidade de germinação (IVG), comprimento e massa seca de plântulas (raiz e altura da parte aérea). As sementes de Platymiscium floribundum expressam seu máximo vigor em ambiente iluminado independentemente da temperatura. Palavras-chave: vigor; espécie florestal; fotoblastismo; jacarandá.
Germination is negatively influenced by water scarcity and by temperatures above or below the optimal range of the species, so it is necessary to know the critical point of absorption for the species or cultivar. The objective of this work was to evaluate the effect of water stress, simulated by solutions of polyethylene glycol 6000 (PEG 6000) at different temperatures, on the germination and vigor of seeds of four cultivars (Branca, Orelha de Vó, Rosinha and Roxinha) of beans (Phaseolus lunatus L.). The water stress simulation was performed using PEG 6000 solutions at concentrations of 0.0, -0.2, -0.4, -0.6, -0.8, -1.0, and -1.2 MPa at temperatures of 25, 30, and 35 ° C. The analyzed variables were percentage of germination at first count, germination speed index, length of aerial part and primary root of seedlings, and dry mass of the respective parts of the seedlings. The seeds of the cultivar Orelha de Vó were more sensitive to water stress, with 88% germinating up to the potential of -0.6 MPa at the tested temperatures. The cultivars Branca, Rosinha, and Roxinha germinated (94, 100, and 100%, respectively) up to the potential of -0.8 MPa. Water stress simulated by PEG (6000) negatively affects seed twinning and seed vigor of bean cultivars.
ABSTRACT:The species Clitoria fairchildiana Howard, native to the Amazon region, by a rustic species and be of rapid growth, has been useful in heterogeneous reforestation for the reclamation of degraded areas, used in the planting of streets, public squares, roads and parking lots, due to its wide, leafy canopy and its rapid growth. The work was developed in the Laboratory of Analyses of Seeds of Centro de Ciências Agrárias of Universidade Federal da Paraíba. Thus, this study aimed to evaluate the physiological potential of C. fairchildiana seeds submitted to different drying times. The experimental design completely randomized, with treatments distributed in a factorial 4 x 5 (temperatures and periods of drying). It was evaluated to determine the water content after the drying processing for each period (0, 6, 12, 18 and 24 hours). For the evaluation of the effect of temperatures (35, 40, 45 and 50 °C) were performed the following tests: water content, germination, germination speed index (IVG), as well as length and dry mass of roots and aerial portion of seedlings. Drying of seeds of C. fairchildiana is recommended at the temperature of 35 °C, within drying 6 hours without compromising the physiological quality of seeds.
Os testes rápidos de vigor são utilizados atualmente pelas empresas produtoras de sementes para avaliar a qualidade dos lotes. A indústria sementeira com a evolução tecnológica, exige cada vez mais rapidez na separação de lotes de alto vigor. Dessa forma, o trabalho objetivou verificar a eficiência e rapidez da atividade respiratória das sementes para diferenciar o vigor de lotes de sementes de feijão. O trabalho foi realizado na Universidade Rural de Pernambuco, conduzido no Laboratório de Análise de Sementes com três lotes de feijão adquiridos em municípios do estado de Pernambuco. Foram realizados alguns testes e determinações: teor de umidade, peso de mil sementes, germinação, primeira contagem da germinação, comprimentos e massa seca da parte aérea e raiz, condutividade elétrica, emergência de plântulas, comprimentos de parte aérea, raiz e massa seca da parte aérea. O índice de velocidade de emergência indicou o lote 3 e 1 como sendo os de maiores potencias fisiológicos e o lote 2 como o de menor. As sementes de feijão do lote 2, nos testes de germinação, índice de velocidade de germinação, índice de velocidade de emergência, massa seca de parte aérea e raiz como sendo o lote de menor vigor, e o que teve a menor liberação de CO2 no teste de atividade respiratória. O teste de atividade respiratória pode ser utilizado para determinar o vigor de sementes de feijão a partir de 12 horas de embebição.
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