Cristina Ferreira Larré

Potential physiological of rice seeds treated with 24-epibrassinolide

Plant growth regulators are involved in promoting and inhibiting germination process, and include the brassinosteroids. The objective of the research was evaluate the performance of different concentrations of 24-epibrassinolide on the seed physiological quality and seedling growth in two lots of rice cv. IRGA 422CL. The experiment was carried out in the Seed Laboratory and at in the greenhouse in the Botany Departament, Pelotas Federal University (UFPel). The seeds of both lots were treated with increasing concentrations of 24-epibrassinolide, zero, 0.01, 0.1, 0.4 and 1.0 μM, for a period of two hours and evaluated by the tests of germination, the first germination count, the germination speed index, emergence, emergence speed index, electrical conductivity, shoot and root length and shoot and root fresh and dry matter. A randomized complete design with three replications was used with three replications. Means were compared by the Tukey test at 5% probability and subjected to polynomial regression analysis. Lower (0.01 and 0.1 μ M) 24-epibrassinolideo concentrations increased the seed physiological potential of cv. IRGA 422CL and therefore provided higher growth rates in the initial period of crop establishment. The increase in the plant hormone concentration accelerated the seed deterioration process reducing the viability and vigor of cultivar seedsstudied. Generally in all the determined characteristics, concentrations less than or equal to 0.4 μM 24-epibrassinolide produced a positive response in the seed physiological quality rice cv. IRGA 422CL.

Copper and zinc interactions: morphophysiological responses in sweet potato plants ( Ipomoea batatas L.)

Interacao cobre e zinco: respostas morfofisiologicas em plantas de batata-doce ( Ipomoea batatas L.) O objetivo do estudo foi avaliar o efeito conjunto de cobre (Cu) e zinco (Zn) sobre batata-doce, segundo parâmetros morfologicos, perfi l mineral e metabolismo antioxidante. Para tanto, as mesmas foram colocadas em sistema hidroponico e cultivadas em diferentes combinacoes de micronutrientes: T1 (0,041 mM Cu + 0,085 mM Zn [controle]); T2 (0,041 mM Cu + 0,850 mM Zn); T3 (0,123 mM Cu + 0,085 mM Zn) e T4 (0,123 mM Cu + 0,850 mM Zn). As plantas cultivadas em T2, T3 e T4 apresentaram reducao dos parâmetros morfologicos, aumento do conteudo de H2O2 e da peroxidacao lipidica quando comparadas ao controle. O aumento de Zn independente da concentracao de Cu (T2 e T4) causou diminuicao na absorcao e transporte de macronutrientes na planta; promoveu mecanismos de competicao, sequestro e compartimentalizacao de micronutrientes nas raizes e ativou a atividade das enzimas antioxidantes.