Response of the Germination of Bean (Vigna unguiculata�L. (Walp) to the Toxic Effects of Heavy Metals

Acosta-Marcano Katiuska,Aiello-Mazzarri Cateryna,Atencio-Acosta Katheryn,Jimenez-Pitre Iris,Molina-Bolivar Geomar

doi:10.17485/ijst/2018/v11i35/131555

Abstract

Objective: To evaluate the toxic effects of metals on the crop Beans (Vigna unguiculata L. (Walp). Materials and Methods: assays of seed germination, elongation of the root, growth of hypocotyl and radicle in these plants as biomonitoring parameters varying concentrations of metals. The metals selected for this study were Cd and Pb. Findings: The seeds of V. unguiculata were sensitive to the presence of metals in comparison to the behavior of plants witnesses, showing all the biomarkers evaluated sensitivity to Cd and Pb however did not complete blockade of the germination and initial growth of seedlings, being the effect more dramatic by the presence of cadmium than with lead, observing a maximum values in the germination rate of 63 and 80%, respectively, in comparison with the control treatment, which were correlated with strongly to changes in morphology and anatomy of the seed. Application/Improvements: The Bean was able to survive and tolerate these polluting metals, so it could be used for the ecotoxicological monitoring of contaminated soils for future studies of phytoremediation. Keywords: Heavy Metals, Seed Germination, Toxic Effects, Vigna unguiculata

Highlights

The contamination of agricultural soils by heavy metals has grown abundantly in recent decades, adversely affecting the soil-plant system, as these tend to accumulate in the soil from waste, irrigation of wastewater sewage treatment, extensive use of chemicals, fertilizers and improvements in agricultural practices, representing a greater risk to human health when the plants develop tolerance mechanisms against metals and when these plants are incorporated into the food chain, representing a risk to consumers at primary, secondary, and human[1]
The toxicity of heavy metals affects the germination process by inhibiting the absorption of water[3, 4], competition for the absorption of nutrients[5, 6], alteration of metabolism, the photosynthetic system, breathing[7]; permeability of membranes and the activity of enzymes linked to the membrane[8], seed viability, alteration of the process of cell division of the root apices, delaying the process of mitosis and altering the process of root elongation, arriving to cause the death of the embryo[9], in addition to fault in the morphology of the same
In relationship has indicated that cadmium is a strong inhibitor of the germination process[16, 17], which inhibits the imbibition of seeds, Percentage, Index and speed of germination[18], by limiting the amount of water of the seeds exposed to this metal, reducing the water content of the future seedlings[19], appreciating a direct correlation as it increases the concentration of metal, coming to inhibit the germination of 77%20

Summary

Introduction

The contamination of agricultural soils by heavy metals has grown abundantly in recent decades, adversely affecting the soil-plant system, as these tend to accumulate in the soil from waste, irrigation of wastewater sewage treatment, extensive use of chemicals, fertilizers and improvements in agricultural practices, representing a greater risk to human health when the plants develop tolerance mechanisms against metals and when these plants are incorporated into the food chain, representing a risk to consumers at primary, secondary, and human[1]. The effects of the metals in the g ermination of seeds depend on the differences between species in the structure and anatomy of the seed[3], type, concentration and distribution of metal[9], stage of development and maturity of the organs of the plant and may induce only a delay in the process of germination, without lead directly to the loss of seed viability[10, 11]. Different metals have been associated with alterations in plant germination, previous studies have shown that mercury (Hg), zinc (Zn), cadmium (Cd), cobalt (Co), plumbum (Pb) and nor reduce germination in lentils, radishes, mustard and rice seeds. Arsenic toxicity induced by significantly reducing the percentage of germination in a 70% of rice seed and a 9% in the root length[12]

Methods

Results

Conclusion