ABSTRACT
The protection of persimmon fruits (Diospyros kaki L.) from postharvest fungal infestation with Alternaria alternata (A. alternate; black rot) is a major agricultural and economic demand worldwide. Edible coatings (ECs) based on biopolymers and phytocompounds were proposed to maintain fruit quality, especially with nanomaterials' applications. Chitosan nanoparticles (NCt), rosmarinic acid bio-mediated selenium nanoparticles (RA/SeNPs) and their composites were produced, characterized and evaluated as ECs for managing persimmon black rot. The constructed NCt, RA/SeNPs and NCt/RA/SeNPs composite had diminished particles' size diameters. The ECs solution of 1% NCt and NCt/RA/SeNPs composite led to a significant reduction of A. alternata radial growth in vitro, with 77.4 and 97.2%, respectively. The most powerful ECs formula contained 10 mg/mL from NCt/RA/SeNPs composite, which significantly reduced fungal growth than imazalil fungicide. The coating of persimmon with nanoparticles-based ECs resulted in a significant reduction of black rot disease severity and incidence in artificially infected fruits; the treatment with 1% of NCt/RA/SeNPs could completely (100%) hinder disease incidence and severity in coated fruits, whereas imazalil reduced them by 88.6 and 73.4%, respectively. The firmness of fruits is greatly augmented after ECs treatments, particularly with formulated coatings with 1% NCt/RA/SeNPs composite, which maintain fruits firmness by 85.7%. The produced ECs in the current study, based on NCt/RA/SeNPs composite, are greatly recommended as innovatively constructed human-friendly matrix to suppress the postharvest destructive fungi (A. alternata) and maintain the shelf-life and quality of persimmon fruits.
ABSTRACT
Trichoderma species are recognized as biocontrol agents with great potential in inhibiting fungal pathogens that cause significant crop losses. In this study, 15 Trichoderma isolates were collected from various Egyptian locations. Internal transcribed spacer sequencing revealed four different Trichoderma species; Trichoderma harzianum, Trichoderma asperellum, Trichoderma longibrachiatum, and Trichoderma viride. The antagonistic activity of Trichoderma isolates against Fusarium oxysporum f. sp. capsici was evaluated in vitro. The effect of Trichoderma isolates on pepper growth plants in the presence of F. oxysporum was studied in planta. The inhibition of pathogen mycelial growth in vitro ranged between 35.71% and 85.75%. The isolates Ta3 and Tl had the highest antagonistic ability in vitro against F. oxysporum f. sp. capsici. However, Th7 and Th6 of T. harzianum isolates showed the highest values of disease severity reduction under greenhouse conditions. The genetic diversity of the Trichoderma isolates (Ta1, Ta2, Th1, Th2, Th3, Th4, Th5, and Tv) was investigated on the basis of ISSR and SCoT markers. SCoT primers generated a total of 28 bands, out of which 14 (50%) were polymorphic. ISSR primers gave 32 bands, and 11 of these bands (34.37%) were polymorphic.