Improving growing substrates by adding the seaweed Cystoseira baccata

Abstract

We examined the impact of adding the seaweed Cystoseira baccata (Ochrophyta, Sargassaceae) in various forms to two different growing substrates: pine bark and gorse compost. Specifically, we examined the influence of the seaweed on the physical and chemical properties of the substrates, and on their agronomic performance on a lettuce crop. The seaweed was used in a 20% (v/v) proportion and three different forms, namely: fresh (FS), washed fresh (WFS), and washed and dried (WDS). The mixed substrates exhibited no signs of instability. FS and DWS increased the total water retention capacity of pine bark by 20% and 27%, respectively. Adding the seaweed in any of its three forms to this type of substrate, which is poor in nutrients and has a low electrical conductivity (EC), significantly increased its P, K, Mg and Na contents, as well as its EC (from 0.08 dS m–1 in the control substrate to 0.69, 0.12 and 0.27 dS m–1 in those containing FS, WFS and WDS, respectively). On the other hand, only in fresh form (FS) altered the salinity and total K content of a substrate rich in nutrients and salts such gorse compost (from 0.89 to 1.42 dS m−1 in terms of EC and 0.59% to 0.98% in K). All mixtures performed well as substrates for a lettuce crop. Those containing DWS increased aerial mass in gorse compost, while any of the tested formats increased aerial mass in pine bark.

Application of Seaweed Generates Changes in the Substrate and Stimulates the Growth of Tomato Plants

“…A substrate should provide a sufficiently solid structure to produce a suitable balance of air and water for optimal plant development. These ideal conditions can be evaluated by physical properties such as PD, BD, and total pore space [ 1 , 10 ]. Overall, the PD and BD values in the three experimental groups in this study fall within the desired ranges established by Abad-Berjon et al [ 81 ].…”

“…In a previous study, biomass of the brown alga Cystoseira baccata was used as a component of plant substrates and was found to reduce BD and increase porosity [ 10 ]. Decreasing substrate compaction by adding seaweed promotes plant root development and thus benefits crop growth and yield due to improved water and nutrient uptake [ 11 , 81 ].…”

“…In the SE-treated substrate, the concentrations of available Mn and Fe were higher (by 12 and 7%) compared to those of the control ( Table 4 ). As previously noted, one advantage of the incorporation of whole seaweed into a substrate is that this method offers a long-term supply of mineral elements to the soil [ 10 , 81 ]. Although seaweed has a modest content of some inorganic nutrients, it may be useful when natural sources are lacking or as an alternative to the excessive use of chemical fertilizers [ 10 , 23 ].…”

“…Plant substrates are materials that ensure adequate aeration, water, and nutrient supply while providing environments that are initially free of plant pathogens, unwanted seeds, and weeds [ 1 , 10 , 11 ]. The addition of organic materials to substrates to improve the performance of cultivated plants has produced favorable results [ 10 , 12 ].…”

“…Plant substrates are materials that ensure adequate aeration, water, and nutrient supply while providing environments that are initially free of plant pathogens, unwanted seeds, and weeds [ 1 , 10 , 11 ]. The addition of organic materials to substrates to improve the performance of cultivated plants has produced favorable results [ 10 , 12 ]. In particular, the addition of seaweeds and seaweed products to plant substrates is quite promising given that these compounds are biodegradable, non-polluting, and non-toxic in nature [ 13 , 14 ].…”