Preliminary Testing and Bioassays of Nanobioherbicides

Abstract

Despite the advancement in green nanotechnology, specifically nanobioherbicides revolution in agricultural sector, fear of toxicity, and safety of the environment(s)/ecosystem(s) are raised. An easy, fast, accurate, reliable, cost-effective, and direct means of assessing the safety of nanobioherbicides is to carry out plant bioassays. In this chapter, we highlight bioassay procedures for nanobioherbicides with respect to: Pot assay (by collection of soil samples, selection of species for bioassay, seeding and growing bioassay species, and evaluation of plant growth and injury); Field trial; Source tracking of the possible residual effects on raw agricultural commodity using standardized techniques such as the Latin square method for forage crops, and random choosing of lower, middle, or upper alternate for objectivity and all inclusive representation with high precision, accuracy, and prevention of any potential (cross) contamination. For best practice with quality assurance, all valid and available information on the test nanobioherbicide(s) to be documented, even as intrinsic screening by monitoring and evaluating at the very least, parameters such as mass concentration (mg/L), assessment of particle size and surface area distribution of the test substance(s)/nanobioherbicide(s) to establish if the experimental plant(s)/ecosystem(s) has/have been exposed, even as dose metric to be used as standard is dependent on the types of nanobioherbicides. The objectives for the ecological/environmental exposure in a regulatory ecotoxicity study are to track at least 80% of the nominally inherent characteristics of the natural course and behavior of the nanobioherbicide, as applicable in situ. For confirmation, rapid, sensitive and empirical detection techniques of inductively coupled plasma mass spectrometry (ICP-MS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) detect quantities of metal nanobioherbicides. Analysis of radioisotopes-labeling of the nano precursor(s) used to validate exposure and uptake of the nanobioherbicide(s) by soil (micro) organisms but by mathematical models, sorption kinetics can be determined. Correlation coefficient used to infer sorption mechanism, bioaccumulation, and consequently, the transfer of the nanobioherbicide(s) across the food chain. Allium cepa chromosome aberration bioassay ascertains the toxicity of nanobioherbicide(s) in field experimentation. We therefore recommend that the elucidated methodology in this review, be adopted as standard operating procedures for the bioassay of nanobioherbicides, as perhaps might help determine whether nanobioherbicides are present in a particular environment/ecosystem at quantities high enough to negatively impact the development, efficiency, yield and or quality of such environment or ecosystem.