Agricultural uses of plant biostimulants

Abstract

Background Plant biostimulants are diverse substances and microorganisms used to enhance plant growth. The global market for biostimulants is projected to increase 12 % per year and reach over $2,200 million by 2018. Despite the growing use of biostimulants in agriculture, many in the scientific community consider biostimulants to be lacking peer-reviewed scientific evaluation. Scope This article describes the emerging definitions of biostimulants and reviews the literature on five categories of biostimulants: i. microbial inoculants, ii. humic acids, iii. fulvic acids, iv. protein hydrolysates and amino acids, and v. seaweed extracts.Conclusions The large number of publications cited for each category of biostimulants demonstrates that there is growing scientific evidence supporting the use of biostimulants as agricultural inputs on diverse plant species. The cited literature also reveals some commonalities in plant responses to different biostimulants, such as increased root growth, enhanced nutrient uptake, and stress tolerance.

Plant proton pumps as markers of biostimulant action

“…There is a body of evidence of positive effects of these products that are reproduced in laboratory as well as under field conditions (Arancon et al, 2012;Zandonadi et al, 2013;Calvo et al, 2014). Humic substances from vermicompost enhance ATP hydrolysis activity, protein abundance, proton extrusion Zandonadi et al, 2010), and messenger ribonucleic acid (mRNA) levels (Quaggiotti et al, 2004) of the PM H + -ATPases in a way similar to that previously described for the plant hormone, auxin (Frías et al, 1996).…”

“…The term "auximones" was coined to designate organic extracts from peat able to promote plant growth. A hundred years later, several products have been identified as biostimulants, although still lacking proper scientific evaluation, and only proved to work under controlled conditions (for a review see Calvo et al, 2014).…”

Effect of organic fertilization on yield and quality of rosemary (Rosmarinus officinalis L.) essential oil

“…Also it have been reported that an application effect of this substances is the production of phytohormones which promotes the growing (Smolen et al, 2014), all this due to the capacity of this substances to generate soil aggregates, proteins, carbohydrates, aliphatic biopolymers and lignin content, thus favoring the microbial activity, improving soil structure and the development of several beneficial microorganism (Calvo et al, 2014).…”

“…The substance correspond to microorganisms, humic acids, fulvic acids, hydrolyzed proteins, amino acids and algae (Calvo et al, 2014); the application of these substances has been converted into an important strategy for agriculture sustainability, since its properly use allow the combination of either pesticides and/or fertilizers of chemical synthesis without decreasing the crops yield (Cordovilla et al, 1999;Aseri et al, 2008;Ambrosini et al, 2015).…”

“…Other commonly used bacteria is Pseudomonas fluorescenses, species reported as growth promotor, responsible for iron consumption increase and plant growth stimulator under drought conditions (Sharma et al, 2013;Calvo et al, 2014;Gopalakrishnan et al, 2015).…”