Impact of Heavy Metal Contaminated Sewage Sediment on Plant Morphological Parameters of Sudan Grass Hybrid, Grown in a Pot Experiment

Abstract

In addition to industrial activities, mining, transport and landfilling, agricultural activity is also a source of soil pollution. With the use of intensive fertilisers, soil conditioners, disinfectant materials, and pesticides we can pollute the soil to varying degree, but the most significant is the impact of sewage sludge displacement. In this case, the heavy metal content of the soil may increase, and it can become accessible to the plants, thereby entering into the food chain. Several researchers have examined how the herbaceous and woody plants react to heavy metal contamination and whether they are suitable for phytoremediation of heavy metals contaminated areas. Those plant species that can tolerate high concentrations of certain toxic metals (heavy metals) or bind them, are capable of reducing the mobile heavy metal content of contaminated soils. Heavy metals have some - usually negative - effects on all plant life processes (growth, photosynthesis, water balance, ion uptake, etc.), which are also manifested in the external morphological properties of „poisoned” plants. In our pot experiments we examined how the various amounts of sewage sediment influence the morphological properties of the test plant. We chose the test plant sorghum x Sudan grass hybrid (cv. GK Csaba), which has a high production and disease resistance features, beside low demand for terroir or soil.
The experiment was set up with 3 treatments (control, 10% sewage sediment, 20% sewage sediment).
We designed 3 repetitions per treatment with 6-6 plants per repetition. The measured morphological parameters were the total length of the plants, the number of leaves, the length and width of the most developed leaf, leaf plate and stem diameter and the mass of the plant parts above the ground.
According to our results, the above-ground vegetative parts of the plants developed in the same way as the control, under the influence of 10% sewage sediment contamination. Treated plants were not behind the control in respect of development, growth, number of leaves or leaf size. In the case of slight contamination, the above-ground vegetative mass exceeded the values measured in control. In plants treated with 20% sewage sediment, similar results were obtained. The total length, the letter number and the leaf parameters of the plants were not significantly different from the control, and even the weight of the plant increased in this treatment. It can therefore be concluded that the low level of sewage sediment soil loading had no negative impacts on the morphological parameters of the Sudan grass hybrid. It can be supposed that the significant nutrient content of the sewage sediment compensated the toxic effects of the heavy metals present in this material.