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| Author(s): |
Dênis Herisson da Silva
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB) |
| Defense date: | 2011-08-01 |
| Examining board members: |
Takashi Muraoka;
Cassio Hamilton Abreu Junior;
Edmilson José Ambrosano;
Marcio Arruda Bacchi;
Edson Luiz Mendes Coutinho
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| Advisor: | Takashi Muraoka |
| Abstract | |
The common bean (Phaseolus vulgaris L.) and cowpea [Vigna ungüiculata (L.) Walp] are a staple foods in many countries, particularly in Brazil, and it is an important source of protein, vitamins, and minerals including iron and zinc. Cadmium (Cd) is a heavy metal considered one of the most hazardous elements for humans. No data are available on the cadmium (Cd) concentration in grain of these species, especially under conditions of CETESB critical limits in soil (3 mg kg-1). The objective were to determine and compare concentrations of Cd in grain of common beans Phaseolus vulgaris L. and cowpea Vigna ungüiculata L. (Walp.) cultivated in 3 L pots with a typical oxysol, as well as to study the effects and accumulation of Cd in plants with distinct comportment. The trials were arranged as randomized design. In the first experiment, seeds of each species (15 common beans and 5 cowpea cultivars) were sowed in pots (3 mg kg-1 Cd and control), replicated three times. The SPAD índex was measured in plants at the end of vegetative stage and the dry matter yield were evaluated. Cd concentration in grain was determined by ICP-MS. After the selection of major and minor Cd accumulators, these cultivars were sowed in a new trial with 3 treatments 3 mg dm-3 Cd + 109Cd (soil); 109Cd (soil); 3 mg dm-3 Cd (soil) + 109Cd (leaves) with five replications. The CO2 assimilation was measured in vivo. Samples of leaves were collected and the ultrastructure was observed in transmission electronic microscope. The aerial parts of beans plants were exposed to radiographic films and the activity of 109Cd in was determined by liquid scintillation spectrometry. Results: SPAD index were affected in most of plants tested, especially in Young leaves. The minor and major concentration of Cd were observed in BRS Timbó (2,3 mg kg-1) and BR3 Tracuateua (0,6 mg kg-1), respectively. In both cultivars, the CO2 assimilation was affected by Cd phytotoxicity, but there were leaves deformities, chlorosis and leaf abscision in BRS Timbó. Common beans chloroplasts showed more osmiophylics globules compared to cowpea. Autoradiography confirmed low translocation root-to-shoot in caupi BR3 Tracuateua and the concentration of Cd was higher in BR3 Timbó, especially in stem and veins of leaves. In comparison to cowpea BR3 Tracuateua, the common bean BRS Timbó absorb and translocate more Cd applied in leaves to grain, but it is inexpressive in total content of Cd in beans (AU) | |