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Summary: The present study involved valorisation of rice straw by conversion of its constituent polymer xylan and chemically modified xylans into biofilms. Hemicellulosic xylan (19.94%) extracted with 10% NaOH (85 °C, 2.6 h) was chemically modified to acetylated (AX) and carboxymethylated xylan (CMX). Biofilms were prepared by reaction of xylan/modified xylan (1% and 2%) with polyvinyl alcohol using eco‐friendly and cheap cross‐linker citric acid and glycerol as plasticiser. 2% xylan biofilms showed maximum inhibition (94.25%) of DPPH at 4 mg mL−1 which was due to large number of free ‐OH groups (highest intensity of ‐OH absorption bands in FT‐IR spectra). 2% CMX biofilms exhibited maximum antibacterial effectiveness with diameter of zone of inhibition 33.5 and 30.5 mm against Bacillus subtilis and Pseudomonas sp., respectively. This may be due to large number of undissociated COO− ions (citric acid) in CMX biofilms which was evident from lesser cross‐linking observed in their SEM images. 2% CMX biofilms also showed the highest biodegradation (86.5%) which may be attributed to formation of ether bonds along with ester bonds leading to their fast degradation. Owing to good bioactive properties of prepared biofilms, it was concluded that these can be appropriate material for food packaging by replacing synthetic plastics. [ABSTRACT FROM AUTHOR]

Summary: The present study involved valorization of rice straw via production of biopolymeric films loaded with lignin and evaluation of their physical, mechanical, structural, antioxidant, antibacterial and biodegradable properties. Lignin (0.1%, 0.2% and 0.3%) loaded films were prepared by solvent casting method involving successful crosslinking between PVA, citric acid and lignin which was confirmed by ester bond formation at 1710 cm−1 in Fourier transform infrared spectrum. Scanning electron micrographs showed smooth surface in control and wavy surface in lignin film with no cracks. Lignin films possessed thickness, tensile strength and elongation at break in the range 0.127–0.142 mm, 22–31.38 MPa and 11.83–17.63%, respectively. Lightness value of films decreased while yellowness index increased as the level of lignin increased in films. Lignin loaded films showed potential antioxidant activity (51.4–74.6%) and antibacterial efficacy against Pseudomonas (diameter of inhibition zone 4.1 cm), thus suggesting their role in prevention of bacterial food contamination and organoleptic changes in food. The biodegradability tests showed that weight loss experienced by films after burial in soil was above 78.7% which offers a great advantage of these biopolymeric films over non‐biodegradable synthetic plastics, hence, these may be explored further as bioplastics to replace plastic wraps in food packaging. [ABSTRACT FROM AUTHOR]

Under a changing climate, nanotechnological interventions for climate resilience in crops are critical to maintaining food security. Prior research has documented the affirmative response of nano zinc sulfide (nZnS) on physiological traits of fungal-infested rice seeds. Here, we propose an application of trigolic formulated zinc sulfide nanoparticles (ZnS-T NPs) on rice seeds as nanobiostimulant to improve physiological parameters by triggering antioxidative defense system, whose mechanism was investigated at transcriptional level by differential expression of genes in germinated seedlings. Nanopriming of healthy rice seeds with ZnS-T NPs (50 μg/ml), considerably intensified the seed vitality factors, including germination percentage, seedling length, dry weight and overall vigor index. Differential activation of antioxidant enzymes, viz. SOD (35.47%), APX (33.80%) and CAT (45.94%), in ZnS-T NPs treated seedlings reduced the probability of redox imbalance and promoted the vitality of rice seedlings. In gene expression profiling by reverse transcription quantitative real time PCR (qRT-PCR), the notable up-regulation of target antioxidant genes (CuZn SOD , APX and CAT) and plant growth specific genes (CKX and GRF) in ZnS-T NPs treated rice seedlings substantiates their molecular role in stimulating both antioxidant defenses and plant growth mechanisms. The improved physiological quality parameters of ZnS-T NPs treated rice seeds under pot house conditions corresponded well with in vitro findings, which validated the beneficial boosted impact of ZnS-T NPs on rice seed development. Inclusively, the study on ZnS-T NPs offers fresh perspectives into biochemical and molecular reactions of rice, potentially positioning them as nanobiostimulant capable of eliciting broad-spectrum immune and growth-enhancing responses. Schematic illustration of nanobiostimulant action of ZnS-T NPs in rice (Oryzae sativa L.) seeds by triggering antioxidant defense system and plant growth specific transcription factors. [Display omitted] • ZnS-T NPs (10.42 ± 1.92 nm) significantly boosted up the germination parameters of rice seeds in contrast to bulk-ZnS. • ZnS-T NPs enhanced the antioxidant defense system by up-regulating CuZn SOD , APX and CAT genes in rice seedlings. • ZnS-T NPs amplified the CKX and GRF gene expression in seedlings, promoting improved seed germination in pots. [ABSTRACT FROM AUTHOR]