Growth, productivity and phytochemicals of Coriander in responses to foliar application of Acacia saligna fruit extract as a biostimulant under field conditions

Abstract The application of natural extracts to vegetable plants can increase production, optimize nutrient and water uptake, and mitigate the effects of stress on vegetable plants by enhancing primary and secondary metabolism. In this study, Acacia saligna (Labill.) H.L.Wendl. fruit aqueous extract (FAE) was applied as a foliar application to assess and demonstrate its effects on growth, productivity, and phytochemicals of coriander (Coriandrum sativum L.) plants. A. saligna FAE (2%, 4%, and 6%), each combined with 50% of the recommended dose of N fertilizer was applied to coriander plants over the course of two successive seasons in the field. These treatments were compared with the control treatment, which used a 100% recommended dose of N. The four tested treatments were set up in a randomized complete block design with three replicates for a total of 12 experimental plots. Each replicate (experimental plot) was 3 m2 (2 × 1.5 m2) in size and included 300 seeds/m2. The phytochemicals were examined using chromatographic and spectrophotometric methods, where the essential oils (EOs) extracted from leaves were analyzed by Gas chromatography–mass spectrometry (GC–MS), while the phenolic and flavonoid compounds were analyzed by High Performance Liquid Chromatography (HPLC). With the application of A. saligna FAE (4%) + 50% N fertilizer, the levels of total solid content, total carbohydrates, total protein, total phenols, and total antioxidant activity, as well as chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoids, were increased at harvest. The treatment A. saligna FAE at 6% + 50% N fertilizer did not observe significant improvement in the growth parameters of coriander plants because of the anticipated allelopathic effects. By GC–MS analysis, the major compounds in the EO from control treatment were 2-octyn-1-ol (23.93%), and 2-butyl-1-octanol (8.80%), in treated plants with 2% of A. saligna FAE + 50% N fertilizer were (E)-2-decen-1-ol (32.00%), and 1-methoxymethoxy-oct-2-yne (13.71%), in treated plants with 4% A. saligna FAE + 50% N fertilizer were E-2-undecen-1-ol (32.70%), and 3,5,5-trimethyl-1-hexene (8.91%), and in the treated plants with A. saligna FAE (6%) + 50% N fertilizer were phytol (80.44%), and (Z)6,(Z)9-pentadecadien-1-ol (13.75%). The flavonoid components 7-hydroxyflavone, naringin, rutin, quercetin, kaempferol, luteolin, apigenin, and catechin were presented with variable concentrations according to the treatments utilized as identified by HPLC analysis from the methanol extracts of the treated plants with the combination treatments of A. saligna FAE (2, 4, and 6%) and N fertilization (50% from the recommended dose) and control coriander plants (100% N recommended dose). The combination of 50% N fertilizer treatment and the biostimulant A. saligna FAE (4%) seems to improve coriander plant growth while simultaneously lowering N fertilizer consumption. Future research will be needed to further study the effectiveness of several concentrations of A. saligna FAE in various conditions and/or species

Rice-husks synthesized-silica nanoparticles modulate silicon content, ionic homeostasis, and antioxidants defense under limited irrigation regime in eggplants

The utilization of nanoparticles in agricultural land is widely increasing worldwide. The present study takes the advent from converting the rice husk waste to silica nanoparticles (SiNPs) to be used in two years of field experiments, as fertigation treatment, against reducing irrigation by drip system. In this respect, the experiments comprised of three drip irrigation regimes (i.e., 60, 80, and 100 % of crop evapotranspiration, ETc) and four levels of SiNPs (0, 100, 200, and 300 mg L−1). The results indicated that limited irrigation reduced the plant fresh weight, plant height, and yield of eggplants by 15, 25, and 30 %, an average of two years, at the level of 60 % ETc compared to 100 % ETc. However, these negative impacts were alleviated by SiNPs via improving the photosynthetic pigments and relative water content where the plants supplemented with 300 mg L−1 SiNPs had the highest improving effects to be 3.8 mg g−1 FW and 76 % compared to 2.2 mg g−1 FW and 63 % (average of two years), respectively at the drought level of 60 % ETc. Furthermore, SiNPs ameliorated the oxidative damage induced by different water regimes by lessening lipid peroxidation and hydrogen peroxide (10.9 and 85.4 µM g−1 FW) compared to their drought level 60 % ETc (14 and 113 µM g−1 FW). This was associated with stimulating the antioxidant enzyme system by promoting the activities of peroxidases (ascorbate- and guaiacol-dependent types), catalase, and superoxide dismutase as the concentration of silica NPs increased to be (173.84, 12.2, 49.5, and 41 unit/mg/min, respectively) at 60 % ETc and 300 mg L−1 SiNPs compared to only 60 % ETc (100.5, 7.9, 32, and 30.5 unit/mg/min, respectively). Also, efficiently increasing SiNPs levels highly significantly restrained the ionic homeostasis in the leaves of eggplant via retaining the reduction of silicon, potassium, calcium, and magnesium contents at 300 mg L−1 silica NPs especially at 60 % ETc (33, 19, 4.5, and 6 mg g−1 DW, respectively) compared to the corresponding drought level (17.33, 7, 2.1, and 3.7 mg g−1 DW, respectively) which reflected on the up-regulation of water status. Such amelioration effects of SiNPs were recommended during the two studied seasons. Altogether, the synthesized SiNPs efficiently mitigated the negative impacts of limited drip irrigation levels on ionic homeostasis, pigments, oxidative stress, and antioxidant system especially at the level of 300 mg L−1