Effects of ZnO and TiO2 nanoparticles on germination, biochemical and morphoanatomical attributes of Cicer arietinum L

Abstract

With the development of nanotechnology, metal oxide nanoparticles have been applied in many industries, increasing their potential exposure level in the environment, yet their environmental safety remains poorly evaluated. Present work demonstrated the effects of ZnO and TiO2 nanoparticles on the germination, morphoanatomical attributes and biochemistry of Cicer arietinum. The nanoparticles are used in three doses, i.e., 100, 500 and 1000 ppm along with control and each dose has three replicates. Results demonstrated that ZnO nanoparticles did not aid in the germination of seed, whereas TiO2 nanoparticles showed positive impact on germination at 48-h observation. But at 72-h observation both the nanoparticle-treated and control seeds showed 100% germination. Morphological parameters revealed that ZnO nanoparticles have drastic negative impact on both root and shoot length, root and shoot fresh and dry biomass. On the other hand, the status of chlorophyll is almost opposite, i.e., ZnO nanoparticle-treated plants showed higher pigment content than TiO2 nanoparticle-treated plants. From the statistical point of view, it is revealed that ZnO nanoparticle-treated plant showed significantly different results than that of TiO2 nanoparticle-treated plants in Chl ‘a’ (p < 0.001), Chl ‘b’ (p < 0.001), total Chl (p < 0.001) and carotenoid (p < 0.001) content. Therefore, from these observations it can be concluded that ZnO nanoparticles showed positive effect on plant pigment content. Transverse sections of root clearly revealed the formation of vascular bundle, and parenchyma tissue is hampered in all the ZnO nanoparticle-treated plants. However, well-formed vascular bundles and other tissue systems are clearly visible for TiO2 nanoparticle-treated roots. This work shows a combination of both positive and negative effects of ZnO and TiO2 nanoparticles on a dicot plant. Present observation is very much important to understand the morphological, biochemical and anatomical alteration of plant system under the influence of ZnO and TiO2 nanoparticles. This will help to utilize the nanoparticles in a managed way where nanoparticles with harmful effect on biological systems can be used in such a way to reduce their exposure to environment, and on the other hand, nanoparticles showing positive effect on biological systems may be used as growth enhancers or biofertilizers. Moreover, these results further strengthen our understanding of environmental safety information with respect to metal oxide nanoparticle.