The exogenous menadiol diacetate enhances growth and yield by reducing Pb uptake, translocation and its toxicity through tissue nutrients acquisition in cucumber (Cucumis sativus L.)

Abstract

The experiment was conducted to assess whether exogenous application of menadiol diacetate (MD, vitamin K 4 ) could alter nutrients acquisition and mitigate lead (Pb) toxicity in cucumber ( Cucumis sativus L.) plants. The seeds of cucumber were surface sterilized with 0.1% solution of HgCl 2 and primed in three different concentrations (0, 10, 20 μ M) of MD solution for 24 h. The primed seeds were sown in pots filled with sand having different Pb regimes (0 and 4 mM). After 35 d of germination, plants were harvested for biochemical and physiological parameters while the yield attributes were collected from 80 d of germination. The exposure to Pb reduced biomass, increased oxidants such as malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ) and caused nutrients imbalance by decreasing K + , Fe and Ca 2 + ions in the shoots. Further, cucumber accumulated Pb mostly in the roots. However, the exogenous MD reduced oxidative stress and enhanced growth and yield under Pb stress that was linked with MD-mediated increase in photosynthetic pigments and tissue accumulation of beneficial osmolytes (soluble sugars) and nutrients (K + , Fe and Ca 2 + ) while reduction in the uptake of Pb in the roots and transport to the shoots and fruits. The results showed that MD not only enhances growth and yield through nutrients acquisition in cucumber but also decreases Pb accumulation in shoot and fruit, and thus could reduce Pb-driven health hazards in agricultural systems.