Characterization of the Chemical Composition of the Halophyte Salicornia bigelovii under Cultivation

Abstract

Straw of the halophyte Salicornia bigelovii was chemically analyzed for lignocellulosic components, extractives, and ash in relation to varying cultivation conditions (namely, irrigating water salinity and fertilizer grade). Irrigation water contained 10−50 ppt salt, and fertilizer application varied between 1 and 2 gN/m 2 . Composition of the biomass was comparable to traditional lignocellulosic biomasses, containing glucan (up to 27 g/100 g total solids (TS)), xylan (up to 23 g/100 g TS), and lignin (24 g/100 g TS), but also high amounts of ash (up to 53 g/100 g TS) and water−ethanol soluble extractives (up to 25 g/100 g TS). As most of the ash is extractable (up to 90%), a simple water wash is sufficient to bring the ash content down to a typical value found in the lignocellulosic materials. It was found that increasing water salinity used for the plant irrigation decreases lignocellulosic components content, increases ash content, and does not affect extractives content. The fertilizer application rate was not found to influence any of the responses, except for ash composition (lowering mineral content) and its amount in the flowering spike fraction. Stem and spike fractions were found to be significantly different in composition, with stems being closer to a typical lignocellulosic material.

Halophyte Plants and Their Residues as Feedstock for Biogas Production—Chances and Challenges

“…Moreover, the stem fractions of Salicornia bigelovii contained less structural ash, 2-8%, as compared to its seed spikes, 5-14%. Conclusively, stems contained less ash both on the surface and incorporated in the plant matrix when compared to pods [76,78].…”

“…This is reflected in findings from Turcios et al [73] and Turcios et al [74], where cultivating halophytes under different salinity showed an increase in both crude ash and structural ash content with increasing salinity. As stated in Cybulska et al [76], a large portion of initial ash content in the raw Salicornia bigelovii plant was in the form of extractable ash, as irrigating the biomass with saline water showed more salt deposits on the plant surface than being incorporated within the plant matrix. Moreover, the stem fractions of Salicornia bigelovii contained less structural ash, 2-8%, as compared to its seed spikes, 5-14%.…”

“…Following their findings, Salicornia europaea contained the highest ash content of 49%. It is undeniable that halophytes contain very high concentrations of ash, as contrasted with conventional grass, which contains approximately 5-10% mineral content in dry material mainly due to their selective uptake of mineral ions as a mechanism of adaptation in saline environments [51,71,[73][74][75][76][77]. As reported by Akinshina et al [75], there were variations in ash content of the investigated wild and cultivated halophyte plants in different seasons of the year.…”

“…In both stem and seed spike fractions, cellulose concentration was higher than hemicellulose. Likewise, seedless Salicornia bigelovii cultivated under 40 g L −1 NaCl and 1-2 g N m −2 fertilizer had a carbohydrate content of 19-26%, with cellulose having the highest share, while the carbohydrate concentration in the stem fraction was 32-56% [76]. Brown et al [78] showed that cultivating at low salinity (10 g L −1 NaCl) and medium fertilizer grade (1.5 g N m −2 ) contained highest carbohydrate in stem fractions.…”

“…The lignin content, determined as the residual part of the lignocellulosic fraction of the halophyte plant after sugar extraction, has generally been found to be notably lower in the aerial fraction of naturally grown halophytes compared to cultivating under controlled conditions of salinity and fertilizer grades [76,78]. For instance, Brown et al [78] reported a higher Klason lignin content, of 10-17%, in the stems of Salicornia bigelovii as compared to the seed spikes (pods), 5-9%, when cultivated under different salinity:fertilizer concentration ratios.…”