Vol.:(0123456789) 1 3 Journal of Plant Growth Regulation https://doi.org/10.1007/s00344-018-9879-7 Biofertilizing Efect of Chlorella sorokiniana Suspensions on Wheat Growth Rajaa Kholssi 1,3  · Evan A. N. Marks 1  · Jorge Miñón 1  · Olimpio Montero 2  · Abderrahmane Debdoubi 3  · Carlos Rad 1 Received: 15 May 2018 / Accepted: 5 October 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract The potential of microalgae as a biofertilizer in agriculture is increasingly recognized. We studied the efect of applications of Chlorella on growth of wheat in terms of its phytostimulating capacity and its potential for substituting chemical fertilizers. Four biofertilizer treatments were used in this experiment: (i) Biomass of Chlorella sorokiniana harvested by centrifugation from cultures in the exponential growth phase and re-suspended in spent growth medium (Solution 1); (ii) fltered BG11 medium used for algae culture after the algae biomass was harvested (Solution 2); (iii) harvested algae that were re-suspended in fresh BG11 medium (Solution 3); and (iv) fresh BG11 medium (Control). Seeds of Triticum aestivum were germinated in pots containing a growing substrate (peat vermiculite 1:1 (v/v) mixture) and grown for 15 days with applications of the four treatments solutions. In general, plant length was increased by 30% with Solution 2; total dry biomass of aboveground and belowground parts were improved by 22% and 51%, respectively, in treatments with fltrate of Chlorella sorokiniana (Solution 2), as compared to the control, indicating that nutrients and extracellular substances excreted by algae in the fltrate were pertinent to the benefcial efects on plant growth. Keywords Bio-fertilizer · Soil microalgae · Chlorella · Plant growth promotion Introduction Chemical fertilizers improve crop yields by providing essen- tial plant nutrients which are easily available to plants; how- ever, their abuse can be harmful for the environment and their use implies increased production costs which reduce the economic viability of agricultural products (Bobade et al. 1992; Adesemoye et al. 2009). One potential way to decrease negative environmental impacts resulting from continued use of chemical fertilizers is to instead promote inoculation with microorganisms to improve chemical fertility (Choud- hury and Kennedy 2005; Rai 2006), and microalgae may be of use in this regard. Microalgae, as phototrophs, may not only help in replacing chemical fertilizers through benefts to plant growth and crop yield, but also may contribute to CO 2 sequestration because they add organic matter to the soil (Zaccaro et al. 1999; Jeong et al. 2003; Maqubela et al. 2009), thus improv- ing soil structure (De Caire et al. 2000; De Cano et al. 2002; Pandey et al. 2005; Malam et al. 2007; Obana et al. 2007; Maqubela et al. 2009; Saadatnia and Riahi 2009). In addi- tion, microalgal biomass is a rich source of metabolites in agriculture (Nirmal et al. 2018) and also produces extra- cellular polymeric substances (EPS) (Kholssi et al. 2017); freshwater microalgae such as Chlorella vulgaris have been shown to provide high amounts of macro- and micronutri- ents, as constituents or metabolites, such as carbohydrates and proteins (Wake et al. 1992; Elarroussia et al. 2016), and growth promoting factors, such as cytokinins (Stirk et al. 2002; Ördög et al. 2004). Although many studies have highlighted the possibility of fertilizing based on microorganisms, including eukary- otic microalgae, anoxygenic phototrophs, and cyanobacteria, biofertilizers are gaining importance because of their sig- nifcant contributions, particularly to the maintenance of soil * Rajaa Kholssi rajae.kholsi@gmail.com 1 Research Group in Composting UBUCOMP, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain 2 Centre for Biotechnology Development (CBD-CSIC), 47151 Boecillo, Spain 3 Laboratory of Materials-Catalysis, Chemistry Department, Faculty of Science, B.P. 2117, Tetouan, Morocco