Elaeis guineensis phenotypic traits and non-enzymatic antioxidant responses to the combination of biofertilizer and chemical fertilizer in infertile soil

A 7-month glasshouse study was conducted to assess the growth responses, nutrient status, and non-enzymatic antioxidant properties of E. guineensis seedlings grown on infertile Ultisol which were subjected to different combinations of chemical fertilizers (CF) and commercial biofertilizer (IBG) as follows: [T1] 100% CF [T2] 70% CF + 30% IBG biofertilizer [T3] 50% CF + 50% IBG biofertilizer [T4] 70% CF only and [T5] Absolute Control. A combination of CF70 and IBG30 led to 15.8% increase in the growth of seedlings as compared to CF100, presenting significantly higher fresh shoot and root weights as well as an ideal root-to-shoot ratio. Absolute control seedlings on the other hand, showed less desirable phenotypical traits across all the observed parameters. Significantly higher levels of relative chlorophyll were recorded for the seedlings treated with CF70 + IBG30, which positively correlated with the chlorophyll a/b ratio. Moreover, the biofertilizer and chemical fertilization allowed increased uptake of nutrients where higher uptake of B and P was positively correlated (p < 0.05) with enhanced frond production, while larger roots mass was associated with primary growth traits. The positive impacts of the combined IBG biofertilizer and chemical fertilizer application were likely attributed to enhanced accumulation of non-enzymatic antioxidants to counteract the effects of soil infertility, with seedlings in CF70 + IBG30 mostly recorded the highest phenolic, anthocyanin, flavonoid, photosynthetic pigments, DPPH radical activity and proline levels.