Efficiency of seed priming and co-treatment strategies in salt effect mitigation using Nicotiana glauca leaf extract on tomato seedlings (Solanum lycopersicum L.)

H. Maaroufi-Dguimi¹*, S. Gamal Mohammed¹, A. Nasraoui Hajaji² and H. Abdalgadir¹

¹Al-Baha University, Faculty of Science, Department of Biology, SA 65779-7738 Alaqiq, Saudi Arabia
²University of Carthage, National Research Institute in Rural Engineering, Forest Ecology Laboratory, Water and Forestry Bp 10, TN 2080 Ariana, Tunisia
*Correspondence: houda_maaroufi@yahoo.fr

Abstract:

The Al-Baha region suffers from soil salinity, negatively impacting agriculture. Current study examined aqueous extracts from Nicotiana glauca as plant-based biostimulants to alleviate salinity’s effects and reduce chemical fertilizer use. An aqueous extract of N. glauca, applied in ascending doses of 20%, 50%, and 100%, was being used. This biostimulant was applied using two methods: seed priming and co-treatment on the seeds of Solanum lycopersicum L. Results indicated that all tested doses, whether applied through seed priming or co-treatment, enhanced the final germination percentage (FGP) and reduced the mean germination time (MGT) under saline conditions. With priming, the 20% dose was most effective in reducing salt treatment effects on FGP, improving it by 5% compared to untreated salt-stressed seeds. In co-treatment, the 100% dose showed a 4.5% reduction in FGP decline referring to untreated and stressed seeds. For priming treatments, the 20% dose reduced MGT by 22%, while the 50% dose in co-treatment reduced it by 28% compared to untreated and stressed seeds. The priming strategy used in this study did not result in significant enhancements in growth parameters, particularly in the fresh weight (FW) and dry weight (DW) of the epicotyls. As priming, the 20% dose had the most significant mitigation effect on epicotyl FW, DW and chlorophyll (Chl) content by 15%, 10% and 30% referring to untreated and stressed seedlings, respectively. However, all tested biostimulant doses used as co-treatment proved effective in mitigating the negative effects of salt on epicotyl and root FW, DW, and Chl content. Seedlings treated with various strategies and doses showed a smaller increase in malondialdehyde (MDA) and proline (Pro) levels under salinity stress. As stress indicators, both Pro and MDA levels were significantly reduced when a co-treatment strategy was applied. Furthermore, the results indicated that the effectiveness of the N. glauca aqueous extract in alleviating salt stress could be attributed to its content of several phenolics, flavonoids, and tannins, which possess antioxidant properties that enhance the plant’s tolerance against salt-induced oxidative stress.

Key words:

antioxidant activity, biostimulant, flavonoids, germination, polyphenolics, salinity, tannins, tree tobacco

Pericarp of colored-seeded common bean (Phaseolus vulgaris L.) varieties a potential source of polyphenolic compounds

R. Nurzyńska-Wierdak, H. Łabuda, H. Buczkowska* and A. Sałata

University of Life Sciences in Lublin, Faculty of Horticulture and Landscape Architecture, Department of Vegetable Crops and Medicinal Plants, Akademicka 15, PL20-950 Lublin, Poland
*Correspondence: halina.buczkowska@up.lublin.pl

Abstract:

Bioactive substances produced by plants are defined as secondary metabolites causing different pharmacological effects in human organism. Various plant raw materials, some known as vegetables or spices, are their source. Pericarp of white-seeded common bean varieties is a pharmacopoeial product traditionally used as an antidiabetic agent. The object of this study was to evaluate the biological value of pericarp of colored beans (cultivars: ‘Małopolanka’, ‘Nida’, ‘Rawela’, ‘Tip Top’, and ‘Nigeria’) compared to the reference white-seeded cultivar (‘Laponia’). Bean pericarp was characterized by a high level of polyphenolic compounds and antioxidant activity. Its phenolic acid content (expressed as caffeic acid equivalents) was at a similar level, at least 0.1 mg g^-1 (0.01%). The highest amount of flavonoids was accumulated by the cultivars with dark blue and black seeds, respectively 0.138 and 0.139 mg g^-1 DW, as well as by the white-seeded cultivar (0.132 mg g^-1 DW). The highest antioxidant activity (AA) was found for bean extracts of the cultivars ‘Laponia’ and ‘Małopolanka’, respectively 12.35 and 12.10%. Phenolic acid content was significantly positively correlated with AA of the bean extracts tested. This study indicates that pericarp of the colored-seeded bean cultivars is characterized by high biological value and can be used as a source of polyphenolic compounds.

Key words: