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.
Micro-propagation of olive provides the possibility of mass production true to type plants with appropriate attributes in short period of time, compared to conventional methods. Micropropagation of olive requires optimization of protocols adapted to specific cultivars requirements. This experiment was carried out during 2020 and 2021 seasons in tissue culture laboratory of Pomology Department, Faculty of Agriculture, Cairo University in order to evaluate the potential effects of Nano silver at 0, 5, 10 and 20 mg L -1 to improve sprouting percentage and shoot growth of Picual olive cv. The effect of nutrient media composition (MS modified, OM and OM modified) and cytokinins (BAP and Zeatin) on multiplication rate and shoot growth were examined. IBA and NAA (2 and 4 mg L -1 ) were examined during rooting stage. The obtained results cleared that silver Nanoparticles (AgNPs) at 5 mg L -1 recorded the highest percentage of bud sprouting, shoot length, number of shoots/explant and number of leaves/ shoot. Olive medium (OM) recorded the highest shoot length, number of shoots/explant and number of leaves/ shoot compared with OM modified and MS modified media. Also, Zeatin at 4 mg L -1 recorded the highest shoot growth parameters during in vitro multiplication stage. During in vitro rooting stage, both the type and concentration of auxins have a significant influence on number of roots, root length and rooting % of Picual olive cultivar. In conclusion, it is recommended that very low concentrations of Nano silver particles to be used in plants tissue culture on olive media (OM) supplemented with Zeatin at 4mg L -1 .
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’.
Banana is a tropical crop cultivated in warm places. Chilling stress in Egypt is making banana crops less productive. Abscisic acid (ABA), a key plant hormone, regulates metabolic and physiological processes and protects plants from a variety of stresses. In vitro growing banana shoots were pre-treated with ABA at four concentrations (0, 25, 50, and 100 mM) and chilled at 5°C for 24 h, followed by a six-day recovery period at 25°C. By comparing ABA treatments to both positive and negative controls, physiological and biochemical changes were investigated. Chilling stress (5°C) caused a considerable increase in lipid peroxidation and ion leakage and reduced photosynthetic pigments in cold-treated plantlets. Increasing the concentration of ABA to 100 µM enhanced the response to chilling stress. ABA had a major effect on mitigating chilling injury in banana shoots by keeping cell membranes stable and lowering the amount of ion leakage and lipid peroxidation. Also, ABA significantly maintained the photosynthetic pigment concentration of banana shoots; accumulated higher amounts of total soluble carbohydrates and proline; and increased DPPH radical scavenging activity. Furthermore, ABA treatment enhanced cold tolerance in chilling-stressed banana shoots through the regulation of antioxidant enzyme activity. Overall, the results show that ABA is a good choice for protecting banana shoots from the damage caused by chilling stress.
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.
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