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Phosphorus (P) availability in subtropical soils does not often meet the nutritional demand of native tree species such as the ipê-roxo tree (Handroanthus heptaphyllus); therefore, it is necessary to supply P at planting. However, the impact of P on root system growth remains unknown. The aim of the current study was to investigate the effect of P application on root morphology of H. heptaphyllus plants over a 36-month period in a subtropical climate region. During the experiment, the plants subjected to fertilization with 40 kg P ha−1 were compared to untreated control. Plant roots were scanned through minirhizotron system 18 and 36 months after transplant (MAT), and generated images were used to determine total root length, mean root diameter and total root volume. Plant height and leaf P concentrations were also evaluated. Phosphorus application enhanced root and whole plant growth with a more evident effect at 36 MAT, when soil P availability decreased. The results give important information on the cultivation of H. heptaphyllus plants in soils presenting low P availability.

The aims of the present study are to evaluate whether the growth of Pampa biome native grass species Axonopus affinis, Paspalum notatum and Paspalum plicatulum, as well as of invasive grass species Cynodon dactylon, is compromised by excessive Cu availability in the soil (0, 35 and 70 mg of Cu kg-1), to determine the impact of excessive Cu on the physiological responses of the investigated species and to assess whether these species have the potential to enable the phytoremediation of soils contaminated with Cu. C. dactylon presented the best performance in soil contaminated with 35 mg of Cu kg-1. In C. dactylon, the concentrations of chlorophyll b and carotenoids increased, as did the photosynthetic rate and plant growth. Phytotoxic effects of Cu in soil contaminated with 70 mg of Cu kg-1 were more severe on A. affinis and led to plant death. The other species presented reduced photosynthetic and growth rates, as well as increased activity of antioxidant enzymes such as SOD and POD. This very same Cu level has decreased photosynthetic pigment concentrations in P. notatum and P. plicatulum. On the other hand, it did not change chlorophyll a and b concentrations in C. dactylon and increased carotenoid concentrations in it. High values recorded for Cu bioaccumulation-in-grass-root factor, mainly in P. plicatulum, have indicated that the investigated plants are potential phytostabilizers. High C. dactylon biomass production - in comparison to other species - compensates for the relatively low metal concentration in its tissues by increasing metal extraction from the soil. This makes C. dactylon more efficient in the phytoremediation process than other species.

The aims of the present study are to evaluate whether the growth of Pampa biome native grass species Axonopus a nis, Paspalum notatum and Paspalum plicatulum, as well as of invasive grass species Cynodon dactylon, is compromised by excessive Cu availability in the soil (0, 35 and 70 mg of Cu kg -1 ), to determine the impact of excessive Cu on the physiological responses of the investigated species and to assess whether these species have the potential to enable the phytoremediation of soils contaminated with Cu. C. dactylon presented the best performance in soil contaminated with 35 mg of Cu kg -1 . In C. dactylon, the concentrations of chlorophyll b and carotenoids increased, as did the photosynthetic rate and plant growth. Phytotoxic effects of Cu in soil contaminated with 70 mg of Cu kg -1 were more severe on A. a nis and led to plant death. The other species presented reduced photosynthetic and growth rates, as well as increased activity of antioxidant enzymes such as SOD and POD. This very same Cu level has decreased photosynthetic pigment concentrations in P. notatum and P. plicatulum. On the other hand, it did not change chlorophyll a and b concentrations in C. dactylon and increased carotenoid concentrations in it. High values recorded for Cu bioaccumulation-in-grass-root factor, mainly in P. plicatulum, have indicated that the investigated plants are potential phytostabilizers. High C. dactylon biomass production -in comparison to other species -compensates for the relatively low metal concentration in its tissues by increasing metal extraction from the soil. This makes C. dactylon more e cient in the phytoremediation process than other species.

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