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A nanocomposite degradable chitosan-rice-starch (CRS) film was prepared by incorporation of commercial (Comm.) and microbial synthesized silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) using a solvent-casting technique. The prepared films were characterized for thickness, surface color measurement, transparency, presence of crystalline features, surface topography, and surface elemental composition. The fabricated nanocomposite films were evaluated for antimicrobial activity and were observed to curb the growth of test Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) microorganisms in an in vitro media Petri plate study. The screened nanocomposite films were then tested to improve the shelf life of peach fruits (cv. Shan-i-Punjab) in packaging. The nanocomposite films with incorporated NPs decreased the overall surface microbial load and enhanced the shelf life of packed peach fruits as compared to unpackaged and packaged fruits with control film. The lowest percentage loss in weight (4.75%) was recorded in peach fruits packaged with film incorporated with Comm. Ag NPs. The lowest change in diameter (4.25-4.05 cm) and the highest ascorbic acid content (0.51 mg/g) were found in peach fruits packaged with films incorporated with Comm. ZnO NPs. The lowest percent (9.6%) increase in total soluble solids was observed for fruits packaged with films incorporated with Comm. AgNPs. The microbial counts on the surface of the fruit was highest for the unpackaged control treatment and lowest for fruits packaged with Comm. Ag NPs. SEM study of the surface of the peaches showed the presence and adherence of microbial cells (bacteria, yeast, and fungi) on the trichomes and the fruit surface.

Green synthesized metal oxide nanoparticles (NPs) have prominent applications in antimicrobial packaging systems. Here we have attempted for the fabrication of chitosan-based nanocomposite film containing Urtica dioica leaf extract derived copper oxide (CuO) and zinc oxide (ZnO) NPs for shelf-life extension of the packaged guava fruits. Electron microscopy and spectroscopy analysis of the CuO and ZnO NPs exhibited nano-scale size, spherical morphologies, and negative ζ-potential values. The NPs possessed appreciable antioxidant and antimicrobial activity (AMA) in order of CuO NPs > ZnO NPs >nettle extract. Therefore, this work establishes for the first time the successful synthesis of CuO NPs and compares its antimicrobial and antioxidant properties with ZnO NPs. On incorporation in chitosan, the polymer nanocomposite films were developed by solvent casting technique. The developed films were transparent, had low antioxidant but substantial AMA. The NP supplementation improved the film characteristics as evident from the decrease in moisture content, water holding capacity, and solubility of the films. The nanocomposite films improved the quality attributes and shelf life of guava fruits by one week on packaging and storage compared to unpackaged control fruits. Therefore, this study demonstrates the higher antimicrobial potential of the nettle leaf extract derived CuO/ZnO NPs for development of antimicrobial nanocomposite films as a promising packaging solution for enhancing the shelf life of various perishable fruits.

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The prevalence of rough lemon rootstock in India is presently threatened by the spread of Phytophthora root rot. Developing an alternative Phytophthora-resistant rootstock that also withstands other abiotic constraints is a priority for a sustainable citrus industry in India. Complementary progenitors can be found in citrus germplasm to combine the desired traits, particularly between Citrus and Poncirus, a closely related genus. The production of hybrids accumulating the desired dominant traits, irrespective of the heterozygosity level of the parents, is an effective way to develop new candidate rootstocks. Rough lemon was hybridized with Swingle citrumelo, X-639 citrandarin, and GouTou Cheng. A reliable method was developed for greater recovery of hybrid seedlings from these crosses on the basis of morphology and simple sequence repeat (SSR) markers. The greatest proportion of hybrid seedlings resulted from embryo rescue at 95 days after pollination (DAP) (48.5% in rough lemon × X-639 citrandarin and 56.7% in rough lemon × Swingle citrumelo) on the basis of multifoliate leaves. The proportion of hybrid seedlings decreased with increase in embryo development stage after 95 DAP until the last stage of observation (125 DAP). Significantly higher proportion of multifoliate seedlings was recovered by in vitro culture compared with in vivo germination from the mature seeds (26.9% vs. 5.2%, respectively). Swingle and X-639 citrandarin are not homozygous for the multifoliate allele from Poncirus, and GouTou Cheng lacks the multifoliate allele; thus, unifoliate hybrids were selected from all crosses on the basis of SSR marker genotypes.

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