Biostimulative effect of amino acids and green algae extract on capsaicinoid and other metabolite contents in fruits of Capsicum spp.

Biostimulants, such as algae extracts or amino acids, are becoming more common in agriculture because the mentality is to make plants more resistant or tolerant to negative environmental factors, rather than using synthetic chemicals (herbicides, insecticides and fungicides), whose use is decreasing year by year, forcing farmers and companies to develop new environmentally friendly products. In a field experiment, green algae and amino acids were tested as biostimulants on three hot pepper cultivars. A large variability was observed between the effects of the two biostimulants on the cultivars. Green algae-treated ‘Somborka’ and ‘Habanero Red Caribbean’ cultivars had 10% and 5% higher dry matter in seeds compared to control treatment. Total sugar content was negatively affected by green algae extract and amino acids in pericarp in cultivars ‘Chili AS-Red’ and ‘Habanero Red Caribbean’. Total organic acids content was positively affected by amino acid treatment in ‘Habanero Red Caribbean’ pericarp and placenta, with an increase of 5.5 g and 2.1 g/100 g DW, respectively. In terms of total phenolics, all three cultivars were positively affected by amino acid treatment, but not in each fruit part. In terms of capsaicinoid content, the greatest effect of the two stimulants was on ‘Somborka’, which varied from four (pericarp, seed) to 16 (placenta) times compared to the control. Amino acid extract decreased ‘Habanero Red Caribbean’ capsaicinoid content in placenta by about 40%. Amino acids were found to be superior to algal extract, although the effect of both was mostly cultivar specific. For a wider use of biostimulants, it should first be tested whether they are suitable for the cultivar in order to increase and optimize the results.