S06 - Session P3 - Enhancing the performance of leafy greens under nutrient deficiency and salinity stress through the application of protein hydrolysates

Authors: Youssef Rouphael *, Francesco Cristofano, Christophe El-Nakhel, Giuseppe Colla

Protein hydrolysates (PHs) are 'mixtures of polypeptides, oligopeptides and amino acids that are manufactured from protein sources using partial hydrolysis'. PHs have been demonstrated to play key roles as biostimulants through the modulation of plant molecular and physiological processes that trigger growth, increase yield and alleviate the impact of abiotic stress on crops. PHs are known to stimulate the root growth mainly through auxin-like mechanisms, due to the presence of specific peptides (e.g. Root Hair Promoting Peptides), or by increasing the synthesis of indol-3-acetic acid induced by the supplementation of tryptophan, which is the biosynthesis precursor. A more vigorous root system can increase the ability of plants to take up nutrients from the external environment and improve their capacity to tolerate salinity and nutrient deficiency stresses. Presented in this article is a comprehensive look at the scientific literature regarding the widely used biostimulant substances category of PHs. Starting from their origin, the modulation of plants' hormonal networks, physiology, and stress defense systems, their in vivo effects are discussed on the most important leafy vegetables such as lettuce, spinach, rocket etc... The paper concludes by identifying several research areas relevant to PHs-based biostimulant to exploit and enhance the biostimulant activity of these bioactive anb signaling molecules in controlled environment.