Assessment of cellulose-based hydrogel on plant growth and physiology of brassica juncea, Lactuca sativa, and Solanum lycopersicum

Abstract

The application of hydrogel in agriculture has gained attention among the researchers. Hydrogel is a hydrophilic three-dimensional structure, possesses multifaceted properties including a high capacity for water retention and a reduced toxicity to the environment generally. This study was carried out to evaluate the performances of cellulose hydrogel application as a plant growth medium. The assessments include material characterization for two types of hydrogels Hydrogel 1 (Epichlorohydrin 10%) and Hydrogel 2 [(Epichlorohydrin (ECH) 10%, Sodium Carboxymethyl Cellulose (NaCMC) 2%], the effect of hydrogel application on seed germination, plant growth and physiology in three vegetable species (Brassica juncea, Lactuca sativa, Solanum lycopersicum). This study also evaluates the effect of plant-growth promoting rhizobacterium (PGPR) on Lactuca sativa grown in hydrogel 2. Gel fraction value was 92.49% and 95.96% for hydrogel 1 and hydrogel 2, respectively based on the gel fraction analysis. X-ray diffractometry (XRD) results confirms that the cotton linter shows cellulose I form and cellulose II peaks in freeze-dried hydrogel (cryogel). In the attenuated total reflectance fourier transform infrared (ATR-FT-IR) characterizations, the region between 1250 to 950 cm-1 is the confirmation of cross-linking occuring between cellulose and epichlorohydrin (ECH). The field emission scanning electron microscopy (FESEM) analysis showed the hydrogel has a porous structure. The rate of seed germination in hydrogel 1 for B juncea, L. sativa and S. lycopersicum was 71%, 70% and 49%, respectively. Hydrogel application as the growth medium have enhanced the plants’ physical growth performances in general for all plant species. There were some differences in the activity of antioxidant enzymes in the plant growth study. The T-SOD enzyme activities of hydrogel 1 were low in B. juncea, S. lycopersicum and L. sativa. In the CAT enzyme activity, both hydrogel treatments in L. sativa showed significant diferences compared to the control (AB fertilizer only) while the APX enzyme activity was insignificant among all treatments in all species.The plants grown in Bacillus spp. and AB fertilizer (combination treatment) has shown the better physical growth at average. The porous structure and the ability of the cellulose-based hydrogel to retain water are the suitable features to be an alternative medium for soilless agriculture. Overall, hydrogel performance as a plant growth medium is dependent on plant species.