Introduction
Wheatgrass juice (a common addition to “smoothies” or as dried food supplement extracts) has become popular in recent years because it contains a variety of nutrients. Production of wheatgrass in aquaponics is rare. The aim of the present study was to test the influence of different aquaponic irrigation water from African catfish (Clarias gariepinus) production and various hydroponic substrates on the growth of wheatgrass (Triticum aestivum).
Material and methods
Wheatgrass was cultivated in an ebb-and-flood commercial aquaponic system from 30.10.2019 to 19.11.2019 in the FishGlassHouse of the University Rostock, Germany (Figure 1). Three different substrates were used, namely, 100% coconut fiber (C), 70% coconut fiber + 30% perlite (CP), and 50% perlite + 50% vermiculite (PV). Wheatgrass was irrigated by two different effluents from intensive aquaculture unit (IAU) and extensive aquaculture unit (EAU) of African catfish (C. gariepinus) recirculation aquaculture systems and tap water with fertilizer (Control) in triplicates. Plant growth indicators and some nutrients were taken and measured in order to evaluate the growth performance of wheatgrass produced in aquaponics.
Results and discussion
Data analysis showed that, regarding irrigation water, total fresh biomass and root dry mass had no significant difference among all groups. Shoot dry mass was significantly higher in fish water groups. Significantly different root length of all groups had the order of Control>EAU>IAU. The significantly highest SPAD-Index was discovered in IAU. Regarding substrates, the highest SPAD-index value was found in PV and not significantly different from CP. The significantly lowest mortality was in PV. Considering interaction of irrigation water and substrates on wheatgrass, the significantly highest value of shoot fresh mass was in PV and EAU combination. Significantly higher shoot length was in IAU and C, PV combination and EAU and CP, PV combination. Root fresh mass was significantly lower in IAU and C, PV combination. Minerals contents had variation due to co-effect of irrigation water and substrates and coconut and vermiculite substrates had positive influence on mineral content. So as vitamins, however, vitamins production reached partly their highest amount in the combination of fish water with different substrates. Abundant microbes including beneficial PGPMs existing in the aquaponic system and organic form of nitrogen in fish units are assumed to lead to higher contents of some nutrients in fish units (Glick, 2012; Palacios et al., 2014).
This finding showed the potential that aquaponic is a more sustainable way of producing vitamins under aquaponic gardening conditions in future (Palm et al., 2018). Studies of verifying the findings and examining the bacterial populations that inhabit the aquaculture effluents and substrates should be undertaken.
References
Glick, BR. (2012). Plant growth-promoting bacteria: mechanisms and applications. Scientifica. 2012 Oct; 2012.
Palacios, O.A.; Bashan, Y.; de-Bashan, L.E. (2014). Proven and potential involvement of vitamins in interactions of plants with plant growth-promoting bacteria—an overview. Biology and fertility of soils. 2014 Apr; 50(3):415-32.
Palm, H.W.; Knaus, U.; Appelbaum, S.; Goddek, S.; Strauch, S.M.; Vermeulen, T.; Jijakli, M.H.; Kotzen, B. (2018). Towards commercial aquaponics: A review of systems, designs, scales and nomenclature. Aquac. Int. 2018, 26, 813–842.