All growers have an interest in gaining back lost yield-potential from abiotic crop stress such as drought, hyper salinity, temperature, water, and in some regions, herbicide application. Multiple stresses in a season can severely compromise crop production.   

For example, herbicide application can increase oxidative stress in plants through the generation of oxygen reactive species in cells (Gomes et al, 2017) causing cellular damage. This damage, like all damage from abiotic stress, can range from slight to severe, vary by type of stress, and the symptoms may be visible for a few days or weeks. Regardless of how abiotic stress presents itself, a grower needs to mitigate it and get crops back in a positive growth pattern to realize its full yield potential.

One markedly studied option is the use of protein hydrolysates (PHs), specifically legume/plant derived, which have been shown to promote antioxidant activity (Rouphael et al, 2017) and improve plant response to abiotic stress (Lucini et al, 2014). There are many PH products on the market, however, the composition of the products varies widely. Research on legume-derived PH containing a high concentration of peptides has shown to stimulate root growth (Kim et al, 2019), enhance nitrogen use efficiency (Carillo et al, 2019; Lucini et al, 2014), and increase the nutrient mobility in plants (Colla et al, 2013) – all which contribute to improvements in crop stress response.

What are Peptides?

Peptides are amino acids bound together in a specific sequence to form peptide chains. These fundamental components of cells carry out important biological functions. Like a lock and key system, each peptide is a “key” fitting to a specific protein receptor, “lock,” on a cell membrane that stimulates the cell’s function and affects the growth of the plant. There are hundreds of peptide hormones in the plant genome corresponding to numerous physiological functions they “unlock,” including functions that aid recovery from abiotic stress. Moreover, there are many peptides acting as antioxidants preventing oxidative stress.

Legume-derived PH biostimulant induces adventitious rooting responses. (Kim et al, 2019)  Stimulating fine root hair growth allows a plant to take in more nutrients, have better water uptake capacity from the soil, and prepare a plant to handle stress better.

Lucini et al (2014) studied the effects of a plant-derived PH on growth, root morphology, SPAD index, chlorophyll fluorescence, leaf mineral composition, and metabolic profiling of greenhouse lettuce with a plant-derived PH under the influence of salt stress conditions. In this study, application of the biostimulant resulted in a lower rate of percentage-of-yield loss and biomass reduction compared to the control, and the capability to maintain “a better nutritional status (higher N and P) in shoot tissues leading to a higher crop performance.”   

Carrillo et al (2019) found “The foliar application of a [plant-derived] PH increased the yield of spinach plants even under suboptimal N treatment.” This increase in fresh yield was associated to the presence of amino acids and small peptides in the PH which act as signaling molecules that, among other things, induce a “nutrient acquisition response that enhances nutrients acquisition and assimilation.”  

Research, research, and more research.

Colla et al, (2013) measured the effects of a plant-derived PH on maize. Results, indicated in the chart below, illustrate the plant-based PH increased the dry biomass, and it increased the SPAD index – which is an indication of chlorophyll production in the plant. The peptides also substantially increased the foliar content of nitrogen – all indications of improved nutrient uptake and assimilation.

Oxidative stress causes cell membrane lipid peroxidation (generation of MDA) with a loss of cell functionality. Plants have a natural antioxidant defense system comprising non-enzymatic and enzymatic components. PH based biostimulants can mitigate oxidative stress as a source of antioxidants (some petides) and by reinforcing the antioxidant defence system of plants. (Lucini et al., 2014)

MDA (Malondialdehyde) is one of several by-products of lipid peroxidation of cell membranes. Lower MDA levels in the following chart showed that plant-derived PH mitigated the oxidative stress induced by herbicide application in a soybean pot experiment. (Cardarelli et al., unpublished)

There is still so much to be learned!

It is a very bright outlook for the continued use of plant-based PH and the many associated benefits, including the mitigation of abiotic stress.  We are grateful to bring information and learning to you. Interested in some more reading? All the references from this post and links to the corresponding research articles are available by clicking below. Enjoy!

Click for References

Gomes MP, Bicalho EM, Smedbol É, Cruz FV, Lucotte M, Garcia QS. Glyphosate Can Decrease Germination of Glyphosate-Resistant Soybeans. J Agric Food Chem. 2017 Mar 22;65(11):2279-2286. doi: 10.1021/acs.jafc.6b05601. Epub 2017 Mar 8.

Youssef Rouphael, Giuseppe Colla, Maria Giordano, Christophe El-Nakhel, Marios C. Kyriacou, Stefania De Pascale. Foliar applications of a legume-derived protein hydrolysate elicit dose-dependent increases of growth, leaf mineral composition, yield and fruit quality in two greenhouse tomato cultivars.

Kim, H.-J.; Ku, K.-M.; Choi, S.; Cardarelli, M. Vegetal-Derived Biostimulant Enhances Adventitious Rooting in Cuttings of Basil, Tomato, and Chrysanthemum via Brassinosteroid-Mediated Processes. Agronomy 2019, 9, 74.

Luigi Lucini,Youssef Rouphael, Mariateresa Cardarell, Renaud Canaguier, Pradeep Kumar, Giuseppe Colla.  The effect of a plant-derived biostimulant on metabolic profiling and crop performance of lettuce grown under saline conditions.

Carillo, P.; Colla, G.; Fusco, G.M.; Dell’Aversana, E.; El-Nakhel, C.; Giordano, M.; Pannico, A.; Cozzolino, E.; Mori, M.; Reynaud, H.; Kyriacou, M.C.; Cardarelli, M.; Rouphael, Y. Morphological and Physiological Responses Induced by Protein Hydrolysate-Based Biostimulant and Nitrogen Rates in Greenhouse Spinach. Agronomy 2019, 9, 450.

Colla, G., Svecová, E., Cardarelli, M., Rouphael, Y., Reynaud, H., Canaguier, R. and Planques, B. (2013). Effectiveness of a plant-derived protein hydrolysate to improve crop performances under different growing conditions. Acta Hortic. 1009, 175-179 DOI: 10.17660/ActaHortic.2013.1009.21