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Abstract To feed the world’s growing population, the agriculture sector has recently had to strike a balance between reducing its detrimental effects on ecosystems and human health and boosting resource efficiency and production. In reality, pesticides and fertilizers are vital to agriculture and are useful instruments that farmers can employ to increase yield and guarantee steady productivity throughout the seasons under both favorable and unfavorable conditions. Therefore, in the present study, fertilizing with potassium citrate as a foliar spray and humic acid (HA) as a soil application allowed for the evaluation of vegetative growth parameters (plant height, number of leaves/plant), total phenolic content, total carbohydrate, antioxidant activity, the essential oil (EO) composition, and bulb yield of garlic (Allium sativum L.). These were carried out in two field experiments throughout the 2020–2021 and 2021–2022 growth seasons. A gas chromatography-mass spectroscopy (GC-MS) apparatus was performed to determine the chemical composition of the isolated EOs. The antifungal activity of the EOs was assessed against two fungi, Fusarium proliferatum and Macrophomina phaseolina, that cause geranium plants to wilt and decay. The findings indicated that applying HA at a rate of 2 g/L with potassium citrate at a rate of 5 or 10 mL/L produced garlic bulbs with the highest levels of productivity and diameter. The diverse treatments between HA with potassium citrate resulted in significant variations in the bioactive components, such as total phenol content, antioxidant activity, total carbohydrate, and sulfur content. The analysis of the EOs revealed the presence of dimethyl trisulfide, diallyl disulfide, methyl 2-propenyl trisulfide, allitridin, and methyl allyl disulfide and allyl tetrasulfide as main compounds. By gradually increasing the concentration of the garlic EO to 4000 µg/mL compared to the control, the inhibition percentage of fungal growth of F. proliferatum and M. phaseolina was increased. In conclusion, a high concentration of HA with potassium citrate (5 or 10 mL/L), may be suitable and highly appreciated as a fertilizer application to enhance the productivity and EOs content of garlic plants.

Abstract An effective strategy for enhancing fruit production continuity during extended sweet pepper season involves adopting innovative biostimulants such as potassium silicate (PS) and vinasse. Adjusting PS and vinasse concentrations are crucial for maintaining the balance between vegetative and fruit growth, particularly in sweet pepper with a shallow root system, to sustain fruiting over prolonged season. However, the interaction between PS and vinasse and the underlying physiological mechanisms that extend the sweet pepper season under greenhouse conditions remain unclear. This study aimed to investigate the impact of PS and vinasse treatments on the yield and biochemical constituents of perennial pepper plants cultivated under greenhouse conditions. For two consecutive seasons [2018/2019 and 2019/2020], pepper plants were sprayed with PS (0, 0.5, and 1 g/l) and drenched with vinasse (0, 1, 2, and 3 l/m3). To estimate the impact of PS and vinasse on the growth, yield, and biochemical constituents of pepper plants, fresh and dry biomass, potential fruit yield, and some biochemical constituents were evaluated. Results revealed that PS (0.5 g/l) coupled with vinasse (3 l/m3) generated the most remarkable enhancement, in terms of plant biomass, total leaf area, total yield, and fruit weight during both growing seasons. The implementation of vinasse at 3 l/m3 with PS at 0.5 and 1 g/l demonstrated the most pronounced augmentation in leaf contents (chlorophyll index, nitrogen and potassium), alongside improved fruit quality, including total soluble solid and ascorbic acid contents, of extended sweet pepper season. By implementing the optimal combination of PS and vinasse, growers can significantly enhance the biomass production while maintaining a balance in fruiting, thereby maximizing the prolonged fruit production of superior sweet pepper under greenhouse conditions.

There are many technological innovations in the field of agriculture to improve the sustainability of farmed products by reducing the chemicals used. Uses of biostimulants such as plant extracts or microorganisms are a promising process that increases plant growth and the efficient use of available soil resources. To determine the effects of some biostimulants' treatments on the photosynthetic pigments and biochemicals composition of zucchini plants, two experiments were conducted in 2019 and 2020 under greenhouse conditions. In this work, the effects of beneficial microbes (Trichoderma viride and Pseudomonas fluorescens), as well as three extracts from Eucalyptus camaldulensis leaf extract (LE), Citrus sinensis LE, and Ficus benghalensis fruit extract (FE) with potassium silicate (K2SiO3) on productivity and biochemical composition of zucchini fruits, were assessed as biostimulants. The results showed that E. camaldulensis LE (4,000 mg/L) + K2SiO3 (500 mg/L) and T. viride (106 spore/ml) + K2SiO3 (500 mg/L) gave the highest significance yield of zucchini fruits. Furthermore, the total reading response of chlorophylls and carotenoids was significantly affected by biostimulants' treatments. The combination of K2SiO3 with E. camaldulensis LE increased the DPPH scavenging activity and the total phenolic content of zucchini fruits, in both experiments. However, the spraying with K2SiO3 did not observe any effects on the total flavonoid content of zucchini fruits. Several phenolic compounds were identified via high-performance liquid chromatography (HPLC) from the methanol extracts of zucchini fruits such as syringic acid, eugenol, caffeic acid, pyrogallol, gallic acid, ascorbic acid, ferulic acid, α-tocopherol, and ellagic acid. The main elemental content (C and O) analyzed via energy-dispersive X-ray spectroscopy (EDX) of leaves was affected by the application of biostimulants. The success of this work could lead to the development of cheap and easily available safe biostimulants for enhancing the productivity and biochemical of zucchini plants.

Background: Natural plant extracts and microbial antagonists have the potential for use in increasing the fungal resistance and productivity of horticulture plants. Methods: The purpose of this study was to evaluate the ability of both natural plant extracts and microbial antagonists as a biotical control of some fungal pathogens, i.e., Fusarium ssp., Exserohilum ssp. and Nigrospora ssp., along with improving the growth and productivity performance of zucchini under greenhouse conditions. Eucalyptus camaldulensis leaf extract (LE), Citrus sinensis LE, Ficus benghalensis fruit extract (FE), and two microbial antagonists Pseudomonas fluorescens (accession no. MW647093) and Trichoderma viride (accession no. MW647090) were tested under in vitro and in vivo conditions. Through morphological characteristics and the internal transcribed spacer (ITS) region, Fusarium solani (accession no. MW947256), F. oxysporum (accession no. MW947254), Exserohilum rostratum (accession no. MW947255), and Nigrospora lacticolonia (accession no. MW947253) were identified. HPLC analysis was used for the identification of phenolic compounds (PCs) and flavonoid compounds (FCs) in the extracts. Results: The highest inhibition percentage of fungal growth (IPFG) against F. oxysporum was obtained with P. fluorescens, T. viride, and E. camaldulensis LE (4000 mg/L); F. solani with P. fluorescens, T. viride, and C. sinensis LE (4000 mg/L); Exserohilum rostratum with P. fluorescens, Ficus benghalensis FE (4000 mg/L) and E. camaldulensis LE (4000 mg/L), and N. lacticolonia with P. fluorescens. Using HPLC analysis, the abundant PCs in E. camaldulensis LE were pyrogallol, and caffeic acid, those in C. sinensis LE were syringic acid and ferulic acid, and those in F. benghalensis FE were gallic acid and syringic acid. In addition, the abundant FCs in E. camaldulensis LE were kaempferol, and naringin, those in C. sinensis LE were hesperidin and quercetin, and those in F. benghalensis FE were kaempferol and quercetin. Under greenhouse experiments, T. viride and E. camaldulensis LE (4000 mg/L) followed by P. fluorescens + T. viride treatments gave the best results of zucchini plants in terms of leaf area, fruits number per plant, yield per plant, and total yield (marketable and non-marketable). Conclusions: Plant extracts and bioagents can be used to control some zucchini fungal pathogens and increase the productivity performance of zucchini plants.