Cristina Copstein Cuchiara

Conservação de grãos de pólen de mamoneira a baixas temperaturas

The objective of storing pollen is to preserve material for future use, providing optimal conditions to maintain their original germination, vigor and genetic integrity. The aim of this study was to investigate the germination of castor bean (Ricinus communis L.) pollen after storage at low temperatures. For this purpose, pollen of the cultivars IAC 80 and AL Guarany 2002 were used and stored at four different temperatures, -196; -72; -18; and 4oC, for a period of 60 days. The pollen viability was assessed weekly for five weeks, with a last evaluation performed after eight weeks of storage using the in vitro germination test. Culture medium containing 10 gL-1 agar, 100 gL-1 sucrose, 0.004 g L-1 boric acid, pH 6.0 was prepared and poored into cavity slides, where the pollen was evenly distributed over the surface of the medium. The plates were incubated at 20oC in BOD. The experiment was arranged in a 2x4 factorial completely randomized design (2 cultivars x 4 temperatures) for each storage time, with 100 pollen grains analyzed per repetition, totaling six of each treatment. There was significant difference between treatments for the cultivar x temperature interaction in the fifth week of observation (p<0.05). Other cultivar x temperature interactions were highly significant at all times of observation (p<0.01). It is therefore concluded that the use of ultra low temperatures allows the maintenance of castor bean pollen viability until the fifth week of storage.

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.