The effects of neem extract and azadirachtin on soil microorganisms

Abstract

Both neem extract and azadirachtin are widely used in agriculture as organic pesticides because they are nontoxic to humans, animals, and the environment. However, their effects on soil microorganisms and plant growth-promoting rhizobacteria (PGPR), which directly affect soil quality, remain largely unexplored. In this study, the effects of neem extract and azadirachtin on the activity of soil microbes and rhizosphere microorganisms was evaluated. We found that 0.1 and 0.4 gmL -1 of the extract and 1.25 and 2.5 µgmL -1 of azadirachtin inhibited the activity of soil microorganisms in vitro. Treating soil with azadirachtin for two months reduced the number of microorganisms present, while two months of treatment with neem extract increased the number of microorganisms in both the soil and the rhizosphere. The phytopathogenic bacterium Pectobacterium carotovorum was more resistant to azadirachtin than Rhizobium sp. Moreover, treatment of mung beans with neem extract or azadirachtin reduced the number of root nodules and Trichoderma asperellum in the rhizosphere, when compared to the control.

The bio-mechanical properties of coco wood applied with Neem extracts: a potential preservative for sustainable building in Marinduque, Philippines

“…Again, in this analysis, Sample [B] performed better than Samples [A] and [C]. This result is similar to the result of the studies [31][32][33] in which Neem extract improved water resistance and dimensional stability of bamboo culms and its products.…”

A comprehensive review of phytochemical profile, bioactives for pharmaceuticals, and pharmacological attributes of Azadirachta indica

“…Administration of leaves extracts (0.1 and 0.4 g/ml) and azadirachtin (1.25 and 2.5 μg/ml) inhibited in vitro activity of soil growth‐promoting rhizobacteria. Two months treatment of soil with azadirachtin reduced number of microorganisms in soil whereas leaves extracts enhanced both soil microorganism and rhizosphere's activities (Sarawaneeyaruk, Krajangsang, & Pringsulaka, ). Growth disrupting effect of seed extracts in water and organic solvents was observed at imaginai stage of Aedes aegypti larval development.…”

Eco-Friendly Castor Oil-Based Delivery System with Sustained Pesticide Release and Enhanced Retention

“…46,47 ACT is a good alternative to conventional insecticides, displaying no resistance problems due to its chemical complexity and nontoxic nature to mammals, beneficial arthropods, and warm-blooded vertebrates. 48 Unfortunately, ACT has a rapid biodegradability, especially in regard to photothermal factors that would accelerate its decomposition, 17,49,50 which greatly limits its application ranges in the agricultural field. Our results indicated that the decomposition rate of ACT after encapsulation in the WPU carrier was much slower than that of free ACT.…”