Conventional pesticide applications are highly inefficient and it is estimated that over 90% of all pesticides applied are wasted due to off-target delivery, binding to soil, runoff and premature degradation. The use of nanocarriers to promote targeted delivery of pesticides have the potential to revolutionize current agricultural practices. In this work, we encapsulated azoxystrobin, a broad-spectrum fungicide widely used in agriculture, within porous-hollow silica nanoparticles (PHSN) and provided the formulation to <i>Solanum lycopersicum</i> to assess the effects of nanoencapsulated azoxystrobin on the plant growth and soil microbial community. A total of 66% of the total azoxystrobin was successfully encapsulated within the PHSN over 8 days of loading. The loading rate increased exponentially in the first 2 days and then gradually declined from that point onwards until it plateaued at day 8. The release profiles showed that while pure azoxystrobin formulation would provide 100% release within hours, the encapsulated pesticide followed a slow, controlled release over days, reaching 43.5 ± 5.8% after 10 days. The treatments with pesticide demonstrated an inhibitory effect of azoxystrobin in the plant development, with the free pesticide treatment yielding less biomass compared to other treatments and controls. Encapsulated azoxystrobin also inhibited the plant growth when compared to control treatments, however, to a lesser extent than the free pesticide. Five phenotypic traits were measured to quantify the effects on the plant health, including dry biomass, length of roots, length of shoot, number of leaves and length of the longest leaf. The soil microbial community shifted to some extent in all treatments, with the pesticide-dosed treatments showing more significant changes. There is, however, no clear trend to determine whether these changes were responsible for the changes in plant growth previously observed, because none of the shifts negatively impacted key bacterial and fungi communities directly related to nutrient cycling of the soil. Overall, the use of encapsulated pesticide within porous nanocarriers did not negatively impact the plant growth and soil microbiota, and provided sustained release of pesticides.

Impacts of porous silica-nanoencapsulated pesticide on plant growth and soil microbial community

ACS Fall 2021

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