Quote: Abobatta WF. Plant stimulants and horticultural production. MOJ Eco Environ Sci. 2020;5(6):261-265. DOI: 10.15406/mojes.2020.05.00202 Dobbss, L. B., Canellas, L. P., Olivares, F. L., Aguiar, N. O., Peres, L. E.

P., Azevedo, M., et al. (2010). Bioactivity of humic material chemically transformed from vermicompost on plant root growth. 58, 3681-3688. doi: 10.1021/jf904385c According to ref. [20], biostimulants are expected to stimulate root growth against shoots to improve plant resilience in water-limiting environments, allowing plants to explore a deeper soil layer during the drought season and stimulating the synthesis of compatible solutes to restore favorable water potential gradients and water uptake as soil water decreases. Similar positive effects can be given by microbial biostimulants that create absorption surfaces around root systems and bind soil water to the benefit of plants. Bhardwaj, D., Ansari, M. W., Sahoo, R. K., & Tuteja, N. (2014). Biofertilizers play an important role in sustainable agriculture by improving soil fertility, tolerance and plant productivity.

Microbe. Cellular fact. 13:66. doi: 10.1186/1475-2859-13-66 Although the category of plant biostimulants is growing rapidly, there is no agreed regulatory framework or legal definition of biostimulants in the United States. Hanafy, M. S., Saadawy, F. M., Milad, S. M. N. and Ali, R. M. (2012).

Effect of some natural extracts on the growth and chemical components of Schefflera arboricola plants. J. Hort. Sci. Ornamen. Plants 4:26–33. Available online at: idosi.org/jhsop/jhsop4(1)12.htm; idosi.org/jhsop/4(1)12/4.pdf In the United States, the Biostimulants Council has been at the forefront of regulatory and legislative issues related to organic or naturally occurring crop additives, including plant biostimulants. Drought is one of the largest and most common stressors for plants in many parts of the world, especially in arid and semi-arid areas.

Drought stress is a multidimensional stress that usually leads to changes in the physiological, morphological, ecological, biochemical and molecular properties of plants. In addition, it can negatively affect the quantity and quality of plant growth and yield. Plants respond to water deficits depending on the duration and severity of water scarcity as well as plant species, age and stage of development [21]. Ertani, A., Pizzeghello, D., Baglieri, A., Cadili, V., Tambone, F., Gennari, M., et al. (2013c). Humoist-like substances from agro-industrial residues influence nitrogen growth and assimilation in maize (Zea mays L.) plants. J. Geochemistry. Scout. 129, 103-111.

doi: 10.1016/j.gexplo.2012.10.001 Ryegrass perennials treated with a product-based protein and exposed to prolonged stress at high air temperatures showed both improved photochemical efficiency and membrane thermostability than untreated plants [62]. These results provided consistent and interesting results and showed that foliar applications of protein hydrolysates can positively influence plant tolerance to heat stress [63]. This review explained the importance of plant stimulants and their role in improving plant productivity in horticulture, including the classification of plant stimulants and the mechanism of various biostimulants such as protein hydrolysates (PHS), humates, algae extracts and chitosan. A systematic literature search was carried out in which the platforms Research Gate, Academia and Egyptian Knowledge Bank, Web of Science, Google Scholar, AGRIS, were searched for a combination of the following keywords: « plant stimulants », « horticultural plants », « protein hydrolysates », « humates substances » and « algae extracts ». The latest work dealing with plant stimulants has been selected for this review. At low concentrations, these substances are effective and improve nutritional efficiency, tolerance to abiotic stress and/or plant quality, regardless of their nutrient content. These substances, when used exogenously, have effects similar to known groups of plant hormones, the main substances of which are auxins, gibberellins and cytokinins [5]. A major problem in lawn grass management is the summer decline in lawn quality and the growth of cool-season grass species [61]. Based on this, the researchers investigated whether foliar application of trinexapac-ethyl (TE) and two biostimulants (TurfVigor and CPR) containing algae extracts would mitigate the decline in growth of agrostide stolonifera L.) during the summer months and investigated the effects of ET biostimulants on leaf senescence and root growth. Foliar application of TE resulted in significant improvements in the quality, density and chlorophyll content of the lawn compared to the control. TurfVigor and CPR significantly improved visual quality by promoting shoot and root growth. This study suggests that the proper use of ET and certain biostimulants could be effective in improving the summer performance of creeping curved grass.

Learn more about agricultural biostimulants by downloading Agricen`s brochure « Growing for the Future »: Krouk, G. (2015). « How plants response to a combination of signals: are biostimulant effects triggerby a cocktail of molecules? » in Abstracts Book for Oral and Poster Presentations of the 2nd World Congress on the Use of Biostimulants in Agriculture ; 2015 Nov 16–19, eds P. Perata, P. Brown, R. A. Alvarez, et M. Ponchet (Florence: New Ag International), 28. Goñi, O., Fort, A., Quille, P., Mckeown, P. C., Spillane, C. et O’Connell, S.