Aluminium (Al) toxicity is an important stress factor for plants in acidic environments. Currently, there exists a dearth of research information on sustainable approaches that can mitigate the problem of Al toxicity in sub Saharan Africa. It is often assumed that since plants have the ability to synthesize their native antioxidants, they may not need supplementation to cope with stresses. To challenge this assumption, the present study explored the effects of 50 and 200 µM concentrations of lycopene (ly) on the growth and productivity of Amaranthus hybridus subjected to 3 × 10-2 mM concentration of Al at pH 4.6 and 25°C. High performance liquid chromatography (HPLC) was used to determine the peak absorbance at 375 nm and the thiobarbithuric acid (TBA) method was used to determine antioxidant activity of ly. Pre- and post-antioxidant treatments were hydroponically applied to A. hybridus seedlings before and after Al treatment for 72 h. Results show that post-lycopene treatments significantly alleviated Al stress in A. hybridus more than pre-lycopene treatments. It is concluded that though A. hybridus could synthesize its own antioxidants, it is susceptible to Al toxicity-induced stress and post-lycopene supplementation could alleviate the stress situation and enhance growth and productivity. However, A. hybridus plants appear not to need lycopene while not under Al stress.
Key words: Amaranthus hybridus, growth and productivity, hydroponics, aluminium toxicity, stress amelioration, lycopene.
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