Field evaluation and characterization of a novel biostimulant for broccoli (Brassica oleracea var. italica) cultivation under drought and salt stress which increases antioxidant, glucosinolate and phytohormone content

Anthropogenic global warming is affecting crop yield and thus compromising food security. Drought and salinization of the irrigation water or soil are increasingly frequent in most arable land, specifically in arid and semiarid areas such as the Mediterranean basin. Many crops have been displaced or their yield has plummeted in recent years, causing food shortages and price increases. In a context of global population growth and reduction in the availability of natural resources used in agriculture, finding novel tools that help farmers to maintain yield in an increasingly arid and saline scenario is of pivotal importance. This is particularly important in organic agriculture, where the number of available tools is very limited. Biostimulants are substances or microorganisms of natural origin whose function is to stimulate plant processes related to nutrient absorption, nutrient use efficiency, tolerance to abiotic stress or the quality of the agricultural products obtained. In the present work, we have evaluated, in field, the agronomic effectiveness of a novel biostimulant formulation in a cruciferous crop of great interest in the Mediterranean basin (broccoli) under control conditions, water and salt stress. Our research has shown that our product had a positive effect on broccoli production and in delaying flowering time. We have also found that the application of our biostimulant increased enzymatic and non-enzymatic antioxidant defense under drought conditions. Similarly, when exposed to salinity, the biostimulant increased the concentration of different phytohormones and glucosinolates. Taken together, our biostimulant increases the tolerance of broccoli to salt stress and water limitation by increasing the antioxidant response, the level of glucosinolates and eliciting the hormonal response.