This work aimed to evaluate the effect of nitrogen dose management on the growth responses and physiological performance of barley seeds. Two barley cultivars (BRS Brau and BRS Cauê) and four nitrogen doses were used. The experimental design consisted of randomized blocks in a 2 X 4 factorial scheme (cultivars BRS Brau and BRS Cauê x nitrogen doses 120, 150, 180, and 210 kg ha-1). Successive collections of primary data were performed every fourteen days for growth analysis. The analyzed variables were total dry matter, dry matter production and relative growth rate, assimilated partition, and seed electrical conductivity. Increasing nitrogen doses caused a temporal-quantitative difference in growth, partition, and the accelerated aging test of barley seeds. The 150 kg ha-1 N dose resulted in total dry matter over time (Wt) superiority for both evaluated cultivars. The variable dry matter production rate achieved an increase with the 150 kg ha-1 N dose at 70 days after emergence (DAE) for BRS Brau and at 56 DAE for BRS Cauê supporting Wt. The 180 and 150 kg ha-1 N doses increased the relative growth rate for BRS Brau and BRS Cauê.

This Work Aimed To Evaluate The Influence Of Water Restriction And Different Temperatures On The Physiological and biochemical performance of barley seedlings. The work was divided into two studies. First, osmotic potentials were tested to simulate water restriction in barley seeds submitted to different temperatures. The experiment was conducted under controlled conditions at temperatures of 20 and 35 ºc. The statistical design used was completely randomized, in a factorial scheme of 11 (cultivars) x 5 (osmotic potentials), with four replications. The first germination count, germination and dry mass of seedlings were evaluated. From study i, two cultivars with the best performance and one with the worst performance were selected. Afterwards, the experiments of the second study began. The experimental design used was completely randomized, in a factorial scheme 3 (cultivars) x 5 (osmotic potentials), with four replications. Antioxidant enzymatic activity, hydrogen peroxide, lipid peroxidation, total soluble sugars and amino acids were evaluated. Water restriction stress, associated or not with high temperature, affected germination, vigor and initial growth of cultivars. When subjected to water restriction and at 35 ºc, the seedlings showed high levels of enzymes, hydrogen peroxide, lipid peroxidation, amino acids and total soluble sugars.

O objetivo do trabalho foi verificar o desempenho fisiológico e bioquímico de sementes de cevada tratadas e armazenadas por curtos períodos de período. Foram utilizadas as cultivares BRS Cauê e BRS Rubi, a testemunha e os tratamentos de sementes Fipronil BRT 250 FS, Baytan FS, Certeza N, Cruiser Opti e Standak Top e os tempos de armazenamento de 0, 7, 14, 21 e 28 dias, sendo um experimento trifatorial (2x6x5), no delineamento inteiramente casualizado. Foram avaliadas a germinação, o comprimento e a massa seca de parte aérea e de raiz, a atividade antioxidante enzimática de SOD, CAT e APX, a peroxidação lipídica, quantificação de peróxido de hidrogênio e o teor dos açúcares solúveis totais. A cultivar BRS Rubi foi mais sensível quanto a qualidade fisiológica para os tratamentos de sementes utilizados, principalmente Baytan, e ao lango dos períodos de armazenamento. Já o desempenho bioquímico foi afetado pelo tratamento Standak Top para a cultivar BRS Cauê, diminuindo a atividade antioxidante, aumentando a peroxidação lipídica e a quantidade de peroxido de hidrogênio. O armazenamento de sementes de cevada tratadas por curto período de período alterou o desempenho fisiológico e bioquímico das sementes. A cultivar BRS Rubi se apresenta mais sensível aos tratamentos de semente empregados e aos períodos de armazenamento quanto a germinação. O tratamento químico pode reduzir a germinação, comprimento de parte aérea e raiz e modificar negativamente a resposta enzimática da SOD, CAT e APX. O tratamento das sementes em até 14 dias pode contribuir para uma semeadura mais segura.

The objective of this study was to evaluate the effects of essential oils from Thymus vulgaris (thyme) and Cymbopogon citratus (cymb oil) on the germination, physiological quality and enzymatic activities of common bean seeds. The oils were tested at different concentrations (0, 1, 3, and 5 mL kg-1), and effects were assessed through germination, and seedling emergence tests. In addition, the levels of chlorophylls, carotenoids, phenolic compounds, and activities of esterase and acid phosphatase enzymes were evaluated. Cymb oil inhibited germination at higher concentrations, with a germination rate of 66% at 5 mL kg-1, whereas thyme oil, at the highest dose, reduced root dry mass (0.12 g per seedling). At lower concentrations, thyme oil promoted higher chlorophyll contents than cymb oil. Furthermore, enzymatic analysis indicated an increase in acid phosphatase and esterase activities in seeds treated with cymb oil, suggesting distinct physiological responses. Overall, thyme oil at 1 mL kg-1 improved seedling growth and pigment contents, while higher doses impaired seed performance. In contrast, cymb oil at 1-3 mL kg-1 enhanced shoot length, root dry mass, and enzymatic activities, but inhibited germination at 5 mL kg-1.