Seed priming with salicylic acid (SA) has been described as a method with potential to improve seed germination under unfavorable conditions. The present study aimed to evaluate the ability of seed priming with SA to attenuate the impact of water restriction during germination and early seedling growth of tomato. Seeds were subjected to different concentrations of SA (0, 25 and 50 µM) and sowed on substrates at different percentages of the water holding capacity (20, 30, 40 and 100%). The following variables were evaluated: germination, first count of germination, germination speed index, shoots/root length and dry mass, superoxide dismutase, ascorbate peroxidase and catalase activities, contents of hydrogen peroxide and of malondialdehyde. Water restriction significantly decreased the variables related to germination and seedling performance. Despite increasing germination speed and seedling development when combined with well-irrigated conditions, priming with SA negatively impacted those characteristics under water deficit conditions. That was through increases in superoxide dismutase activity and H2O2 accumulation. Thus, it was concluded that seed priming with SA does not improve tomato seed germination and early seedling growth under water deficit.

Aluminum (Al) toxicity is one of the main aspects restricting the development of fabaceous plants grown in soils with spontaneous vegetation prevalence in temperate climate zones. Salicylic acid (SA) minimizes the effects of stress on plants. Therefore, the aim of the current study was to evaluate the ability of SA seed priming to mitigate the effects of Al on seed germination and seedling performance in two Trifolium species. Trifolium vesiculosum (annual) and Trifolium repens (perennial) seeds were primed in solution added, or not, with SA (25 μM) and placed on germination paper moistened with aluminum sulfate (Al 2 (SO 4) 3) solutions at three different doses: 0 mM (control), 0.25 mM (moderate dose), and 1.25 mM (high dose). Seed priming with SA has mitigated the global toxicity effects of Al on T. vesiculosum and T. repens seedlings. Inferior damages were observed in T. vesiculosum root length and dry mass and in T. repens shoot dry mass, after SA pretreatment. T. vesiculosum seed priming with SA in the presence of Al has significantly reduced the osmotic potential of seedling sap. Salicylic acid (SA) has also enabled increased antioxidant activity of enzymes such as superoxide dismutase (SOD) in the two investigated plant species and ascorbate peroxidase (APX) in T. repens. In addition to the increased antioxidant activity, SA-primed seeds reduced the malondialdehyde content in T. vesiculosum seedlings exposed to Al. Overall, seed priming with SA mitigates oxidative effects of Al and improves T. vesiculosum and T. repens seedling performance in the presence of this element.

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R e s u m o ȱȱȱȱȱĚ¹ȱȱǰȱ£ȱȱȱȱ³¨ȱȱȱȱGochnatia polymorpha. ȱ¤ȱȱȱȱ¤ȱŝŖƖȱȱ ȱŘƖȱȱȱ¥ȱȱȱ ŗśǚǰȱŘŖǚǰȱŘśǚȱȱřŖǚ ȱȱȱȱȱ£ǰȱÇȱȱŗŜȱȱȱȱÇǰȱȱȱȱȱȱȱ ȱȱȬ¤ǰȱȱŖǰŝƖǰȱȱȱȱśǰŞȱ + ȱŖǰŘǯȱȱȱ³¨ȱȱȱę¤ȱȱȱȱ £ȱȱ·ȱȱȱȱęȱȱȱȱȱȱȱȱ ȱǻȱ¡ȱǼǰȱȱ¤Ȭ ȱȱȱȱǰȱȱ¹ȱȱ³ȱȱȱȱ ȱŗƖǯȱ ȱȱȱȱȱ³ȱ ȱȱ¹ȱȱ£ǰȱȱȱȱȱȱŗśǚȱȱŘŖǚ ȱ¨ȱȱȱǰȱȱȱȱ ȱǻşǰŞȱȱŗŗǰśƖǰȱǼȱȱȱȱ³¨ȱȱȱǻŖǰŗşȱȱŖǰřśȱȱÇȱȱŗŜȱ ȱȱŖǰŘśȱȱȱÇȱȱȱǼǯȱ ȱ¹ȱȱ¹ȱȱȱęȱȱȱȱ ȱȱȱȱ¹ȱȱǰȱȱ·ȱȱȱȱęǯȱ Palavras-chave:ȱ ǰȱ·ȱǰȱęǰȱ³¨ȱ¡ǰȱȱęàǯ A b s t r a c tȱ¢ȱȱȱĚȱȱȱȱȱȱȱȱȱGochnatia polymorpha, ȱȬ ęȱȱȱȱ ȱǯȱ ȱ¢ȱȱȱŝŖƖȱȱȱŘƖȱ ȱ ȱȬ ȱȱȱȱŗśǚǰȱŘŖǚǰȱŘśǚȱȱřŖǚȱ ȱȱ ȱȱȱǰȱŗŜȱȱȱȱȱȱȱ ȱȱȱ ȬȱǰȱŖǰŝƖȱǰȱȱȱȱśǰŞƹŖǯŘǯȱ ȱȱȱȱȱȱȱȱ ȱȱ ȱȱĴȱȱȱȱ ȱǻȱ¡ȱǼȱȱȱȱȱ ȱȱ ȱ ǰȱȱȱȱȱȱȱȱ ȱŗƖȱ ǯȱȱȱȱȱȱȱȱǰȱȱ ȱȱŗśǚȱȱŘŖǚȱ ȱȱȱȱǰȱȱȱȱȱǻşǰŞȱȱŗŗǰśƖǰȱ¢Ǽȱ ȱȱȱȱȱǻŖǰŗşȱȱŖǰřśȱȱŗŜȱȱȱȱŖǰŘśȱȱȱȱȱȱȬ Ǽǯȱȱȱȱȱȱęȱ ȱ ȱȱȱȱȱȱȱȱȱ ȱęȱ.

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ABSTRACT: This study aimed to evaluate the effect of different levels of self-seeding Italian ryegrass (Lolium multiflorum Lam.) and nitrogen rates - applied additionally after two defoliations - on plant structure, in forage and seed yield. Levels of self-seeding were classified as very high (777 kg ha-1), high (736 kg ha-1), intermediate (624 kg ha-1), and low (234 kg ha-1). Populations were fertilized with zero, 20.25, 40.50, and 60.75 kg ha-1 of supplemental nitrogen applied after two defoliations; respectively, in very high, high, intermediate, and low levels. Higher levels of self-seeding promoted greater forage yield and uniformity of vegetation structure. Number of fertile tillers and number of seeds per plant have benefited by the combination of high self-seeding and supplemental nitrogen fertilization. Despite influencing the uniformity and amount of forage obtained in two defoliations, the very high and low self-seeding levels did not differ in Italian ryegrass seed production. However, linear addition for this same variable was obtained with the inclusion of supplemental nitrogen fertilization. In pastures from low and intermediate self-seeding levels, total dry mass increases linearly with the levels of nitrogen fertilization assessed in this research.

The study aimed to evaluate the initial development, as well as, the chemical characteristics of lettuce plants grown in substrate with high concentrations of bioagent (trichoderma). A completely randomized design with four replicates was used. The treatments, applied to a substrate composed of a blend of vermicompost and commercial substrate, were established by the following doses of the commercial product ICB Nutrissolo Trichoderma: T1) 0.0; T2) 1.0; T3) 2.0; T4) 4.0; T5) 8.0 and T6) 16.0x1011 conidia kg -1 of product. After inoculation, the substrate was placed in trays, where 50 lettuce seeds were sown on each replication. Plants were thinned after emergency stabilization, maintaining ten seedlings per tray. At 28 days after sowing, the characteristics percentage and emergence speed index, leaf area, fresh and dry leaf biomass, volume, length and surface area of the root were evaluated. We also determined the chemical characteristics of the leaves. The percentage of seed germination and the emergence speed index were lower at doses higher than 4.0x10 11 conidia kg -1 of the biological product. All the studied doses influenced negatively in shoot and root development of the plants. The percentage of nutrients in the leaves was higher in treatments with ICB.

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