In recent years, there has been increasing interest in matrix-type influence on forest fragments. Terrestrial amphibians are good bioindicators for this kind of research because of low vagility and high philopatry. This study compared richness, abundance, and species composition of terrestrial amphibians through pitfall traps in two sets of semideciduous seasonal forest fragments in southeastern Brazil, according to the predominant surrounding matrix (sugar cane and pasture). There were no differences in richness, but fragments surrounded by sugar cane had the lowest abundance of amphibians, whereas fragments surrounded by pastures had greater abundance. The most abundant species,Rhinella ornata, showed no biometric differences between fragment groups but like many other amphibians sampled showed very low numbers of individuals in fragments dominated by sugar cane fields. Our data indicate that the sugar cane matrix negatively influences the community of amphibians present in fragments surrounded by this type of land use.

In order to understand the allelochemical action of Byrsonima intermedia A. Juss. and B. verbascifolia Rich. ex A. Juss., the effects on germination, initial growth and cell cycle of Lactuca sativa L., exposed to leaves and fruits of this species, were evaluated using the sandwich method. Data were subjected to analysis of variance and means were compared by the Scott-Knott test (p < 0.05). For the parameters germination percentage and germination rate index, no difference between Byrsonima spp. was observed, and B. intermedia fruits were responsible for the highest inhibition of lettuce germination, compared to the leaves. Root elongation in lettuce exposed to B. verbascifolia organs showed stimulatory effects and B. intermedia organs showed inhibitory effects on root growth. The mitotic index showed the allelopathic effect of Byrsonima spp. by the reduction in cell division in lettuce root meristem, and the stimulus in root elongation was caused by B. verbascifolia, understood as a consequence of cell expansion, not mitotic activity. An aneugenic effect of Byrsonima spp. was observed, and the highest frequency of C-metaphase and stickness was found in B. verbascifolia fruits and B. intermedia leaves.

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Common bean (Phaseolus vulgaris L.) is an important source of protein and carbohydrates, besides being rich in several mineral nutrients. In a flooding situation, the low availability of oxygen may result in hypoxia or anoxia condition. Therefore, this study aimed to evaluate the responses of the common bean cultivar BRSMG-Uai subjected to hypoxia in different phenological phases, analyzing its responses in terms of growth, productivity, carbon and nitrogen metabolism. Thus, seeds of common beans were germinated and when the seedling reached growth stage V1, they were transferred to plastic boxes containing 40L of nutritive solution with steady aeration. Distinct series of plants were exposed to air-restriction on their roots for nine days, in three different phenological phases V3/V4, R6 and R7. Samples were collected for biochemical and growth analyses in a completely random design (n=6). The plants subjected to low availability of oxygen presented a reduction in bean number, displaying the greatest loss in productivity in V3/V4, conferring the highest sensitivity to hypoxia in this phase. On the other hand, there was an increase in sugar concentration in leaves, and it was also possible to observe an increase in hydrogen peroxide in leaves and roots, concomitant with a decrease in superoxide dismutase activity in all phenological phases. There was also an increase in ascorbate peroxidase activity in roots in R6, as well as in nitrate reductase activity. We conclude that the cultivar BRSMG-Uai presents sensitivity to low oxygen availability, and the phenological phaseV3/V4 is the most critical for it.