Phytotoxicity evaluation of rice straw biopolymer-based hydrogels

The disposal of rice crop residue, i.e. straw, from fields via burning is a major concern because of its hazardous effects on the environment. Therefore, it is essential to find other ways for effective valorization of such unavoidable residues available in abundant amounts in the field. As an alternative to burning, major components of rice straw, i.e. such as cellulose, hemicelluloses and lignin, could be utilized for the production of various high-value biomaterials. The current study presents the synthesis of hydrogels from rice straw biopolymers, i.e. microcrystalline cellulose (MCC) and lignin, using glutaraldehyde/epichlorohydrin crosslinkers, followed by the evaluation of their effects on seed germination. Hydrogels were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) analyses. The phytotoxicity of hydrogels was evaluated by using them as media for germinating monocot (wheat) and dicot (moong bean) seeds. The growth of seedlings on all hydrogels was observed to be better than that of control seedlings, which confirmed the positive role of the hydrogels on the germination of monocot and dicot seeds. Hence, they could be further explored for improving plant growth, especially in drought areas.