Facile Fabrication of Wood Fiber–Hydrogel Composites for Enhanced Water and Nutrient Efficiency in Soilless Cultivation

Restrictive regulations on the use of peat and increasing consumption in modern horticulture production have created an irreconcilable contradiction. Wood fibers (WF) produced from forestry residues are considered as a promising peat substitution. However, their poor water- and nutrient-holding capacity limit their application. Here, wood fiber-hydrogel composite (WF-Gel) was developed via a one-pot strategy by grafting poly(acrylic acid-co-acrylamide) (P(AA-co-AM)) onto WF. The structure of the hydrogel network incorporated with WF was confirmed by FTIR spectrophotometry, scanning electron microscopy, X-ray diffractometry, and thermogravimetric analysis. The growing substrate amended with WF-Gel showed higher physical properties, including water-filled porosity (~62.33%) and water-holding capacity (~44.93%) compared with peat incorporated with WF. The pot experiment revealed that WF-Gel significantly increases the chlorophyll content and relative growth rate of choy sum (<i>Brassica rapa</i> var. <i>parachinensis</i>), especially at the initial transplanting stage. Moreover, choy sum grown in a substrate containing WF-Gel showed a significant increase in biomass accumulation. Additionally, nutrient content and irrigation water-use efficiency data indicated that WF-Gel as a growing medium strongly promotes the water and nutrient efficiency of choy sum. Therefore, the incorporation of this hydrogel modification strategy is a promising approach to promote the water- and nutrient-use efficiency of WF as a soilless substrate component.