Nano pyrite (FeS2) root priming enhances chilli and marigold production in nutrients-deficient soil: A nano strategy for fertiliser tuning

A large part of the world has nutrients-deficient soil, where chemical fertiliser application is cost prohibitive. Plants with superior root system architecture perform better in such soils by virtue of their superior mineral assimilation potential. Earlier we showed that seed pre-treatment with nano-pyrite (FeS 2 /Py) results in improved root architecture in chickpea, Sesamum , carrot and beetroot. Here we have developed a root-priming strategy for crops requiring transplantation. As a case study, roots of 28-days-old chilli and marigold seedlings were primed for 3 h in an aqueous suspension of nano-pyrite (@100 µg/ml), prior to transplantation, resulting in significant increase in the fruit and flower yield respectively. Chilli yields for control (without nitrogen, phosphorous, potash (NPK) or root priming), with NPK application only, with nano-pyrite root-priming only, and with nano-pyrite root-priming along with NPK application were found out to be 1327.60 ± 85.15, 1966.46 ± 11.15, 2118.23 ± 67.69, and 3322.43 ± 109.89 (mean (kg/ha) ± standard deviation, n = 3 replications) respectively. Mean marigold flower number per plant for control and nano-pyrite root priming were found to be ~ 13 and ~ 27, respectively ( n = 30). We validate these results by proposing an ionic model explaining the observed root-priming effect. Temporal pH measurement during 3 h of root priming; elemental analysis of roots after 3 h priming and 30 days of transplantation after priming; and root system analysis after 30 days of transplantation were further conducted to firmly establish the role of nano-pyrite in redesigning the root architecture. This study is one of its kind in establishing, that application of a nano-material can modulate root architecture and thereby, influence the overall performance of the plant.