Mango fruit (cv. Seddik) is known as a delicate fruit for storage after harvest. Herein, carboxymethyl cellulose (CMC) and guar gum-based silver nanoparticles (AgNPs) were used as fruit coatings, and their effects on postharvest storage behavior and quality attributes were investigated. AgNPs were synthesized using a chemical reduction approach and then combined with CMC and guar gum as coating bases. Mango fruits were coated with the developed and pre-characterized CMC-AgNPs and guar gum-AgNPs, and then packed and stored at 13 °C for 4 weeks. The results showed an increase in weight loss, respiration rate, total soluble solids (TSS), total sugars, and total carotenoids over the storage period. However, this increase was comparatively less significant in coated fruits compared to uncoated fruits. Firmness and titratable acidity (TA) significantly decreased during storage, but this decrease was less in coated fruits. Silver traces in fruit pulp samples were not detected. These findings showed the efficacy of CMC-AgNP and guar gum-AgNP coatings in delaying mango fruit ripening and maintaining fruit quality during cold storage. Therefore, these coatings could be promising alternative materials for extending the postharvest life and marketing period of mango fruit.

In this study, we describe the synthesis of zinc oxide nanoparticles (ZnO NPs) and evaluate the impact of alginate-based ZnO NPs (Alg–ZnO NPs) on microbiological activity, storage behavior, and physico-chemical properties of ‘Kiett’ mango fruit. The fruits were coated with alginate and Alg–ZnO NPs and then stored at 13 °C; uncoated mango fruits were used as controls. ZnO NPs were synthesized and characterized, confirming the formation of spherically shaped particles with sizes ranging from 12 to 15.1 nm and a zeta potential equal to 31 mV. Alg–ZnO NPs exhibited the same inhibition capacities against the growth of E. coli and S. aureus bacteria. The cold-stored fruits showed an increase in weight loss, respiration rate, total soluble solids (TSS), total sugars, and total carotenoids over the storage period. However, this increase was comparatively less significant in coated fruits than in uncoated ones. Alg–ZnO NP treatment maintained better fruit quality, controlled the decay incidence, and increased the shelf life of the mango fruits. Firmness and titratable acidity (TA) significantly decreased during storage, but this decrease was reduced in coated fruits. We conclude that Alg–ZnO NP treatment could be a promising safe alternative for maintaining fruit quality, extending the storage period, and increasing the shelf life of mango fruits ‘cv. Kiett’.

Salicylic acid (SA) was sprayed on “Seddik” mango transplants at concentrations of 0, 0.5, 1, and 1.5 mM. Then, the mango transplants were subjected to 72 h of chilling stress at 4 ± 1 °C, followed by a six-day recovery under greenhouse conditions. Untreated transplants exposed to chilling stress represented the positive control, while those not exposed were the negative control. SA-pretreated mango transplants were compared to the positive and negative controls, evaluating physiological and biochemical changes. The SA concentration of 1.5 mM L⁻¹ was the most efficient in mitigating chilling injury (CI) in mango transplants by maintaining the integrity of the leaves’ cell membrane and minimizing electrolyte leakage (EL), specifically after six days of recovery. SA increased photosynthetic pigment content, total sugar content, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and decreased proline and total phenolic content in the “Seddik” mango transplants’ leaves. After exposure to chilling stress, the antioxidant enzymes’ internal activities in SA-pretreated chilled mango transplants improved, especially on the sixth day of recovery, compared to the negative control; the transplants nearly attained normal growth levels. Thus, SA can protect plants against the adverse effects of chilling stress.

Guava (Psidium guajava L.) has been considered a hard-to-root species, where the percentage of rooting and survival of the stem cuttings is low. To enhance the rooting potential of guava stem cuttings, the current study was conducted to investigate the influence of NAA and IBA alone or combined with silver nanoparticles on the rooting of guava semi-hardwood cuttings. Silver nanoparticles were synthesized using the chemical reduction method. UV/VIS spectra and TEM micrographs confirmed the synthesis of silver nanoparticles (AgNPs) with an average particle size ranging d from 14.8 to 32.4 nm, and zeta potential confirmed the stability of AgNPs due to the high negative charge of zeta potential. Semi-hardwood cuttings of guava were subjected to six treatments, including the dipping in separate aqueous solutions of IBA, NAA, IBA-AgNPs, NAA-AgNPs, dipping in IBA followed by dipping in AgNPs solution (IBA+AgNPs), and dipping in NAA followed by dipping in AgNPs solution (NAA+AgNPs). Results indicated that the hormone type significantly affected all rooting parameters; higher measurements of rooting percentage, root number, root length, and root weight were recorded with IBA treatment, whereas NAA recorded significantly lower values. Auxin-AgNPs (IBA-AgNPs and NAA-AgNPs) and the double-dipping treatments improved rooting efficiency compared with the auxin treatments alone. Cutting of NAA-AgNPs treatment developed a lower number of long roots, while IBA-AgNPs recorded higher values of all root parameters. The present results demonstrated the stimulatory effect of auxin and AgNPs treatments on the rooting of guava stem cuttings.

Artificial pollination is a prerequisite to achieve a sufficient yield of palm trees; hence the identification of superior male palm trees as a standard pollen source for date palm growers has a high priority. The current study was carried out to assess phenotypic diversity among four date palm males namely Hayani, Meghal, Fardh, and Ghannami Ahmer. The genetic diversity and phylogenetic relationships between palm genotypes were performed using eighteen quantitative morphological parameters of both vegetative and reproductive parts (leaf, leaflets, spines, and spathe). Principal components analysis and hierarchical clustering was performed to identify the differences and similarities between the studied genotypes. Results showed significant differences in morphological parameters between the four male palm trees. Most of the selected morphological parameters could be used as quantitative markers for the identification of date palm male genotypes. Principal component analysis showed that, the studied parameters formed two major homogeneous groups of variables, which possessed a high proportion of the observed phenotypic diversity among the studied date palm males. Cluster analysis showed that Fardh, Ghannami Ahmer, and Meghal, are closer related than Hayani; Ghannami and Fardh males showed the highest genetic similarity while the lowest similarity index was detected between Hayani and Ghannami Ahmer males.