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.

Rice is a crop that presents sensitivity to cold, especially in the germination phase, which leads to high economic losses. Alternative management forms are essential to increase tolerance to low temperatures, and seed priming represents a promising tool. The objective of this study was to investigate the priming effect of the aqueous extract of carrot roots on rice seeds to increase tolerance to low temperatures during germination. Seeds from cultivars BRS Querência (cold-susceptible) and Brilhante (cold-tolerant) were soaked for 24 h in concentrations of 0, 25, 50, and 100% carrot extract, sown on germitest paper and conditioned in BOD for 21 days at 15 °C. As a control, the seeds soaked in water were also germinated at 25 °C. They were evaluated for germination, first germination count, and germination speed index to calculate the stress indices: tolerance index, susceptibility index, and harmonic mean. They were also evaluated for the length and dry mass of shoot and root. The results showed that the rice seeds conditioning in carrot extract effectively reduces the damage caused by cold, significantly increasing the germination speed and the percentage of final germination and the growth evaluations, more expressive at 100% concentration. The stress indexes are efficient in estimating the tolerance of the cultivars and the effect of the different conditions in low-temperature conditions, highlighting the superiority of the Brilhante cultivar.

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The sunflower has a fundamental role in the global economy, being one of the most important crops for oil production. The plants have a short growing season and it adapts well to different soil conditions and unfavorable weather. The present study aimed to evaluate the impact of drought on leaf water potential, the content of photosynthetic pigments and antioxidant responses in two cultivars of sunflower. Seeds of the M735 cv. and MG2 cv. were sown in pots and four plants were maintained per pot that was arranged randomly. Plants were grown in a greenhouse, and two months after sowing, subjected to water stress: Irrigated and not irrigated. Evaluations were performed after 1, 5 and 12 days of induction the stress treatment. Significant reduction in leaf water potential at 5 and 12 days in M735 cv. and 12 days for MG2 cv., were observed. The pigment content did not differ between treatments. There was no change in antioxidant enzyme activity for the M735 cv., though the levels of H 2 O 2 increased in non-irrigated plants after 12 days. The SOD

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