Ameliorating efficacy of spermidine and kinetin for rhizospheric chromium and lead- indices for physiological studies of Mash [Vigna Mungo (L.) Hepper]

Abstract

Heavy metals toxicities have adverse effects on plant physiology while plant growth regulators improve the physiological
phenomena of plants. An experiment was conducted to find out the ameliorative effects of spermidine and kinetin for toxicity
of rhizospheric chromium (Cr) and lead (Pb) on four varieties of Mash bean [Vigna mungo (L.) Hepper]. Four varieties i.e.,
MASH 80, MASH 88, MASH 97 and MASH ES-1 were grown in pots with four replicates of each. Pots were arranged with
complete randomization. After fifteen days of germination, the lead (Pb) was added @ 20 mg/kg and 40 mg/kg soil, while
chromium (Cr) was supplied @ 30 mg/kg and 60 mg/kg soil in the form of PbCl2 and CrCl3 solutions. Spermidine @ 1.0 mM
and Kinetin @ 100 mM were foliarly sprayed separately twice at age of 15 and 30 days of plants. Physiological parameters
like nitrate reductase activity, photosynthetic rate, transpiration rate, substomatal CO2 concentration, stomatal conductance,
water use efficiency were determined at the age of physiological maturity. Among the major significant findings, it was noted
that the photosynthetic rate was increased by both spermidine and kinetin application. The maximum value (8.79) for
photosynthetic rate was revealed under exogenous foliar spray of spermidine among the hormones. Transpiration rate was
increased by kinetin. Substomatal CO2 concentration was decreased by both hormones. Kinetin increased stomatal
conductance and decreased water use efficiency. The maximum value (169.40) for substomatal CO2 concentration was
obtained by kinetin. The maximum value (1.08) for stomatal conductance was observed by foliar spray of kinetin among the
hormones. Spermidine increased water use efficiency and nitrate reductase activity. The maximum value (7.78) for water use
efficiency was recorded by spermidine. Conclusively, it was evident from the results that toxic effects of heavy metals were
ameliorated by plant growth regulators and these findings can be helpful in ameliorating the metal toxicity effects in future. ©
2021 Department of Agricultural Sciences, AIOU