Evaluation of agronomic efficiency and stress resistance on Swiss chard via use of biostimulants

Climate change, global development and population growth are driving an increased demand for greater agricultural productivity while using fewer resources. This shift has highlighted waste-derived products as potential alternatives for primary resource based fertilisers in the field of agronomic bioeconomy. Among these products, two examples are tailor-made fertilisers (TMF - a blend of biobased ingerdients: ammonium sulphate and nutrient-rich concentrate) and protein hydrolysate based biostimulants. A pot experiment was conducted using Swiss chard (Beta vulgaris), chosen for its high vitamin A and K content, as a model plant. The study aimed to investigate the impact of biostimulants, specifically the combination of biobased TMF and synthetic fertiliser (calcium ammonium nitrate). The assessment incorporates both agronomic parameters (such as crop yield, nitrogen uptake, and nitrogen fertiliser replacement value) and physiological indicators (chlorophyll, proline, and malondialdehyde). These parameters were tested at three incremental N rates (70 %, 100 %, and 130 % of recommended crop N demand) and 4 conditions (only treatments, treatments + temperature stress, treatments + biostimulants, and treatments + biostimulants + temperature stress). Distinct patterns emerged for tailor-made and synthetic fertilisers with different N dosages showing increased N uptake and yield (p < 0.05). The use of biostimulants has a beneficial effect on plants, increasing chlorophyll concentration, proline content, and stress tolerance through diverse effects on N uptake, enzymatic activity, hormonal regulation, and photosynthesis. Temperature stress had minor effects on yield in Swiss chard (p > 0.05), yet biochemical stress responses, such as proline accumulation, were observed significant in treatments with biostimulants. Notably, plants treated with synthetic fertiliser under stress conditions exhibited higher malondialdehyde levels (p > 0.05), indicating increased susceptibility to membrane damage and oxidative stress. Further research is required using biostimulants and tailor-made fertilisers across diverse crop varieties under controlled field conditions. This investigation will ascertain the feasibility of replacing synthetic N fertilisers in commercial settings.