Comparison of the Effect of Flurochloridone and Fluoranthene on the Root and Shoot Anatomy and Morphology of Pea Plants (Pisum sativum)

Despite current efforts to minimize the impact of industry on ecosystems, the environment is polluted by a range of foreign substances, that can have a negative impact on the living organisms. Examples of widely studied substances are polycyclic aromatic hydrocarbons (PAHs) and recently, substances commonly used in conventional agriculture. In our study we focused on the morphology and anatomy of the vegetative organs of pea plants treated with the active substance of herbicides, flurochloridone (FLC), in concentration representing the residual amount in the soil (5 & mu;M), and PAH fluoranthene (FLT) in concentration representing the middle to high environmental load (5 & mu;M). During the long-term cultivation in nutrient solutions modified by the mentioned pollutants, the growth parameters of roots and shoots were observed in the three growth phases (4 and 8 fully developed leaves and the flowering phase). The growth parameters and observation of the morphology were supplemented with root and stem anatomical analysis using the transverse cross-sections. Both xenobiotics caused the decrease in the biomass production, while the more significant inhibition of growth, compared with control plants, was detected in FLC-treated plants, where the root system was reduced up to 75% and growth parameters of the shoots were reduced about more than 50%. The decrease in root biomass production was accompanied by changes in root branching. FLT treatment caused milder growth inhibition, it was observed about 50% reduction of the root system induced by the shortening of the main and lateral roots. Less pronounced, was also the decrease in stem length caused by FLT. Similar information was obtained about the different degrees of effect of FLC and FLT using anatomical analysis. Both studied substances increased the main root diameter accompanied with increase of the average number of the primary cortex layers. Their influence also caused the more intensive formation of exodermis. Changes in anatomical architecture were also observed in stem, where the FLC treatment changed the arrangement of the vascular bundles and decreased their average number. Our elementary morpho-anatomical study suggests that FLC despite its trace concentration could be more detrimental to plants than FLT, known for its harmful effect on living organisms, in relatively higher concentration.