Evaluation of biostimulants in growing media for vegetable seedlings

To improve environmental sustainability, to reduce production costs, to enhance the plant's resilience to biotic and abiotic stress are main goals in modern nursery production. The aim of this work was to evaluate the possibility of reducing the use of fertilizers into a substrate using a commercial biostimulant based on vegetal extracts (caidrin, alginic acid and betaine) without detrimental effects on vegetable seedlings. These active components should guarantee a correct and balanced nutrition, increasing the plant's ability to absorb nutritive elements and enhance its capacity to overcome abiotic stress. Trials were repeated twice in 2015 and 2016; they were carried out on different vegetables, representative of various botanical families and production growing cycle length. The experiments compared five different combinations of fertilizer and biostimulant application rates in a peat-based substrate. Plant growth measurements were collected both on seedlings ready to be transplanted and on aged plants. Data collected show that in many cases the biostimulant, added to the recommended or reduced dosage, made it possible to reduce fertilizer use to one-half of standard practice without negative effects on the seedlings growth and quality. In many cases the addition of biostimulant to the substrate improved significantly the foliage SPAD values. The best results were obtained using the recommended dosage of biostimulant with half the amount of ready-to-use fertilizer into growing media.