Foliar applied fullerol differentially improves salt tolerance in wheat through ion compartmentalization, osmotic adjustments and regulation of enzymatic antioxidants

Abstract

Earlier we reported that seed pre-treatment with PHF promoted early seedling growth and salinity tolerance in wheat. As a way forward, experiments were conducted to investigate whether and to what extent foliar spray of fullerol could influence growth and physio-biochemical responses in salt stressed wheat. In a control experiment, seeds were sown in sand filled pots (500 g) under control and 150 mM NaCl stress. After 15 days, foliar spray of fullerol at 0, 10, 40, 80 and 120 nM concentration was applied and the data for various morpho-biochemical attributes recorded after 2 weeks. Fullerol caused improvements in shoot growth attributes while had least effect on root growth traits. Increase in total chlorophyll while reduction in Car/Chl ratio was evident under salinity in response to fullerol spray. Only 40 and 80 nM spray treatments improved antioxidant activities and reduced H₂O₂ contents while MDA contents which increased due to salt stress, remained unaffected by foliar spray. Fullerol spray also improved sugars, proline and free amino acids under salinity. During second experiment under natural conditions, 60 day old plants grown in sand filled pots (10 kg) under 0 and 150 mM NaCl were foliar sprayed with selected concentrations (0, 40 and 80 nM) of fullerol. Salinity inhibited gas exchange and grain yield attributes while fullerol-sprayed plants exhibited recovery. Fullerol spray resulted in high root and shoot K⁺ and shoot Ca²⁺ contents. Also, increase in shoot and root P, while lesser shoot Na⁺ was recorded due to 80 nM spray under salt stress. Overall, 40 and 80 nM fullerol spray improved photosynthetic activity, osmolytes accumulation and altered tissue ion compartmentalization which contributed to improvement in grain yield attributes under salinity.

Keywords: Abiotic stress; Antioxidants; Fullerol; Nanoparticles; Salinity; Wheat; Yield.

Fig. 1

a–f Influence of fullerol foliar spray on non-enzymatic antioxidants and osmolytes in wheat under control (grey filled square box) and 150 mM NaCl salinity (red filled square box) (n = 4; mean ± SE). Different lowercase letters in each attribute are significantly different at P < 0.05 (DMR). DW, dry weight; FW, fresh weight

Fig. 2

a–f Influence of fullerol foliar spray on yield attributes of wheat under control (grey filled square box) and 150 mM NaCl salinity (red filled square box) (n = 4; mean ± SE). Different lowercase letters in each attribute differ significantly at P < 0.05 (DMR)

Fig. 3

Photograph showing the growth of seedlings raised from seeds harvested from plants treated with 40 and 80 nM fullerol foliar spray. Harvested seeds were grown in Petri plates under a control (0 mM NaCl) and b salinity (150 mM NaCl)