ResumoO presente trabalho foi conduzido com o objetivo de avaliar diferentes volumes de água destilada no substrato e temperaturas na germinação e no vigor de sementes de melão, variedade pepino. O experimento foi conduzido no Laboratório de Análise de Sementes da Unimontes, no período de fevereiro a abril de 2012. A semeadura foi realizada em rolos de papel do tipo "germitest", umedecidos com volumes (mL) de água destilada equivalentes a 1,0; 1,5; 2,0; 2,5 e 3,0 vezes o peso do substrato seco, sem adição posterior de água, com três folhas por rolo. Os rolos foram mantidos em germinadores previamente regulados nas temperaturas constantes de 25 e 30°C e alternada de 20-30ºC. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 5 x 3 (volumes de água destilada e temperaturas), com quatro repetições de 50 sementes. Avaliou-se a porcentagem de germinação, índice de velocidade de germinação, comprimento de raiz e parte aérea, massa fresca e seca de plântulas. Diante dos resultados, conclui-se que as combinações de volume de água destilada no substrato e a temperatura de exposição que proporcionam melhores respostas na germinação e no vigor das sementes de melão, variedade pepino, são de 1,0 vez o peso do substrato seco na temperatura de 30ºC e 3,0 vezes o peso do substrato seco a 25 e 20-30ºC. Dentre as temperaturas estudadas, a temperatura de 30ºC promove melhores respostas em todas as variáveis analisadas, sendo recomendada como temperatura adicional para avaliação da qualidade fisiológica de sementes de melão. Palavras-chave: Cucumis melo L., análise de sementes, teste de germinação AbstractThis study was conducted to evaluate different volumes of distilled water and substrate temperatures on germination and vigor of melon, cucumber variety. The experiment was conducted at the Laboratory of Seed Analysis Unimontes in the period february to april 2012. Sowing was done on paper rolls like "germitest" moistened with volumes (mL) of distilled water equivalent to 1.0; 1.5; 2.0; 2.5 and 3.0 times the weight of dry substrate without further addition of water, with three sheets per roll. The rolls were kept in germination preset constant temperatures of 25 to 30°C and 20-30°C alternate. The experimental design was completely randomized in a factorial 5 x 3 (distilled water volume an temperatures), with four replicates of 50 seeds. We evaluated the germination percentage, germination velocity index, root
ResumoObjetivou-se com esse trabalho avaliar as diferentes épocas de colheita sobre a qualidade fisiológica de sementes de crambe, cultivar FMS Brilhante. O experimento foi instalado na Área Experimental da Universidade Estadual de Montes Claros -UNIMONTES, em Janaúba, MG, em 03 de setembro de 2011. A primeira colheita dos racemos foi realizada aos 14 dias após a floração, quando aproximadamente 50% das plantas apresentavam floração plena. As demais colheitas foram realizadas em intervalos de seis em seis dias, perfazendo um total de cinco colheitas. Foi determinado também o acúmulo de unidades térmicas, em graus dia, durante os intervalos de tempo. Os racemos colhidos foram levados ao Laboratório de Análise de Sementes da UNIMONTES, onde permaneceram sob condições ambientais até a realização das análises. As sementes foram avaliadas quanto ao teor de água, à germinação e ao vigor (matéria seca de sementes, massa de mil sementes, emergência de plântulas e índice de velocidade de emergência). O delineamento experimental utilizado foi inteiramente casualizado, com cinco épocas de colheita, que consistiram nos tratamentos, e quatro repetições. As sementes de crambe apresentam dormência pós-colheita. O máximo acúmulo de matéria seca (maturidade fisiológica) ocorreu aos 26 dias após a floração. Conclui-se que a melhor época para realizar a colheita de sementes de crambe, cultivar FMS Brilhante, com maior qualidade fisiológica (máximo de germinação e vigor) ocorre no período de 14 a 26 dias após a floração, que representa uma soma térmica de 1111,1 a 1302,15 graus dia. Palavras-chave: Crambe Abssinica Hochst, germinação, maturidade fisiológica, vigor AbstractThe objective of this study was to evaluate different harvest seasons on the seed quality of crambe, cultivar FMS Brilhante. The experiment was carried out at Experimental area of the Montes Claros State University -UNIMONTES in Janaúba-MG, on September 3, 2011. The first raceme harvest was performed 14 days after flowering, when approximately 50% of the plants showed full flowering. The other harvests were performed every six days, making a total of five harvests. Accumulation of thermal units in degrees day during time intervals was also determined. The collected racemes were taken to the Laboratory of Seed Analysis at UNIMONTES, when they remained under ambient conditions until beginning the analyses. Seeds were evaluated as for water content, germination and vigor (dry
The sugar apple is highly dependent on the pollination and fruit tree pollen performance is crucial for successful fertilization and fruit set. The objective of this study was to determine the cardinal temperatures for in vitro pollen grains germination and evaluate the effect of temperature on pollen tube growth of sugar apple. The experimental design was in a completely randomized with eight treatments (10, 15, 20, 25, 30, 35, 40 and 45 ºC), four replicates and each plot was constituted by two slides per parcel. The cardinal temperatures were determined by evaluating in vitro germination of pollen grains and pollen tube growth in standard culture medium. It also assessed the pollen tube growth and the percentage of germination in vitro depending on the type of pollen grain arrangement (monad, dyad, triad and tetrad). In vitro germination of pollen grains and pollen tube growth varied significantly with temperature. The maximum germination recorded (48.13 %) and the maximum lengths of pollen tubes (536.45 μm) were obtained when pollen grains were cultivated at 25 ºC. The estimated cardinal temperatures were 9.7, 26.9 and 44.2 ºC. Among the pollen grain arrangements, tetrads pollen grains were observed in higher proportions, however, monads pollen grains presented higher germination percentage. Index terms:In vitro germination; pollen viability; monads; tetrads; pollen tube. RESUMOA pinheira é uma fruteira altamente dependente da polinização e o desempenho do pólen é determinante para o sucesso da fertilização e frutificação efetiva. O objetivo deste trabalho foi determinar as temperaturas cardinais para a germinação in vitro dos grãos de pólen e avaliar o efeito de diferentes temperaturas no crescimento dos tubos polínicos de pinheira. O delineamento experimental foi o inteiramente casualizado, com oito tratamentos (10, 15, 20, 25, 30, 35, 40 e 45 ºC), quatro repetições, sendo cada parcela experimental constituída por duas lâminas. As temperaturas cardinais foram determinadas por meio da avaliação da germinação in vitro dos grãos de pólen e do crescimento do tubo polínico em meio de cultura padrão. Avaliou-se também o crescimento do tubo polínico e o percentual de germinação in vitro em função do tipo de arranjo do grão de pólen (mônade, díade, tríade e tétrade germinados). A germinação in vitro dos grãos de pólen e o crescimento dos tubos polínicos da pinha variou significativamente com a temperatura. A máxima germinação in vitro registrada (48,13 %) e o máximo comprimento dos tubos polínicos (536,45 µm) foram obtidos quando os grãos de pólen foram cultivados a 25 °C. As temperaturas cardinais estimadas foram 9,7, 26,9 e 44,2 ºC. Dentre os arranjos de grãos de pólen, foi observada maior percentagem de tétrades, no entanto, os grãos de pólen do tipo mônades apresentaram maiores porcentagem de germinação.Termos para indexação: Germinação in vitro; viabilidade polínica; mônades; tétrades; tubo polínico.
Lichens (Algal-Fungal association) synthesize unique chemical substances with different biological activities. Three pure lichen compounds were assayed to evaluate their potential insecticidal activity against the termite Nasutitermes corniger on Petri dishes. Usnic, fumarprotocetraric and barbatic acids were isolated and purified from the lichens Cladonia substellata, C. verticillaris and Cladia aggregata, respectively, using thin-layer and high-performance liquid chromatography for attesting their purity. Nuclear proton magnetic resonance and infrared spectrophotometry was used for their chemical characterization. After exposure, mortality of termites (workers and soldiers) was determined during 11 days period. The termiticidal effect was influenced by the exposure time and the type of member colony. The results showed that lichen substances, tested at 5, 7 and 10 mg mL-1, have a termiticidal activity (~100%) on worker termites after 8th days of treatment, in comparison with controls. However, no significant effect on soldiers was found. These findings indicate that usnic, fumarprotocetraric and barbatic acids are potential compounds for use in the control of this urban pest.
Baby corn maize (Zea mays L.) is a highly profitable alternative to farmers due to its short crop duration, being harvested at the juvenile stage. It demands large amounts of nutrients in a short time, especially nitrogen, which is responsible for the rapid development of crop. This study aimed to evaluate the effect of topdressing application of different doses of nitrogen on the vegetative and spikelet productivity features in the baby corn crop in Janaúba -Minas Gerais. The experiment was laid out in randomized block design with three replications and four treatments. The treatments comprised four doses of nitrogen (0, 40, 80 and 120 kg ha -1 N applied as urea) top dressed at the V6 (sixty leave with visible auricle) growth stage, which occurs 30 days after sowing the seed. Nitrogen topdressing doses did not interfere in vegetative characteristics of baby corn cultivar Al Bandeirante, but the productivity of spikelet responded to the increasing doses of nitrogen, being the highest productivity at a dose of 120 kg ha -1 N.
Drought is one of the main abiotic factors limiting agricultural productivity, capable of having a major impact on the yield of most crops. The knowledge of the physiological and biochemical mechanisms that differentiate resistance and susceptibility to water deficit among soybean strains can be used in the generation of more tolerant cultivars. In this sense, the objective of this study was to characterize physiologically, two soybean cultivars with different patterns of tolerance to drought in the field, by determining photosynthetic rates, lipid peroxidation levels and antioxidant enzyme activity under three levels of water potential. Upon reaching the V4 development stage, the irrigation of the plants was suspended and three data collection were performed: full irrigation (control); moderate water deficit (Ψ = -1.5 ± 0.2 MPa) and severe deficit (Ψ = -3.0 MPa ± 0.2 MPa). Variations in perspiration rate, stomatal conductance, as well as decrease in photosynthetic rate were significant between the two cultivars, where the water potentials in cultivar BR 16 anticipated on average two days achieving the same water potentials in Embrapa 48 cultivar, thus presenting better efficiency in water use. In addition, the increased activity of enzymes and lipid peroxidation were more significant in the cultivar BR 16, demonstrating that this cultivar is less tolerant to drought than Embrapa 48 cultivar, corroborating to agronomic data previously found in the field.
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