Root ferric chelate reductase (FCR) activity in Annona glabra L. (pond apple), native to subtropical wetland habitats and Annona muricata L. (soursop), native to non-wetland tropical habitats, was determined under Fe-sufficient and Fe-deficient conditions. Four-month-old seedlings of each species were grown hydroponically in a complete nutrient solution containing 90 μm Fe or no Fe. The degree of tolerance of Fe deficiency was evaluated by measuring root FCR activity, chlorophyll and Fe concentration in recently matured leaves and plant growth. Root FCR activity was higher in soursop than in pond apple in the nutrient solution with Fe. However, there were no differences in root FCR activity between species under Fe-deficient conditions. Root FCR activity in pond apple and soursop was not induced in the absence of Fe. Leaf chlorophyll index and Fe concentration, and dry weights of pond apple were lower when plants were grown without Fe compared to plants grown with Fe. Leaves of pond apple grown without Fe became chlorotic within 3 weeks. Lack of Fe decreased the chlorophyll index and Fe concentration in young leaves less in soursop than in pond apple. In contrast, the Fe level in the nutrient solution had no effect on dry weights of soursop. The rapid development of leaf chlorosis and low FCR activity of pond apple may be due to its native origin in wetland areas where there is sufficient soluble Fe for plant growth and development.
In tubers `Kennebec' and `Russet' were applied acetylene, carbide and ethylene to promote sprouting, subsequently the tubers were stored at temperatures of 10 and 15 C. The experiment was a completely randomized, factorial design. The evaluations were done weekly. `Kennebec' sprouted from the second week of applied the treatments to 10 and 15 C while `Russet' sprouted only to 15 C. In the fourth evaluations the effect of promoters was not significantly different to the control. `Kennebec' at 10 C showed greater percentage of sprouting and number of sprout/tuber with respect to `Russet', but at 15 C were not detecte significant differences between the cultivars for these parameters. Number of sprout/tuber in `Kennebec' was not affected by the promoters but `Russet' treated with acetylene and carbide at 10 C showed the largest number of sprout/tuber. The greater sprout length was presented by `Kennebec' in both temperatures.