Potassium silicate and vinasse enhance biometric characteristics of perennial sweet pepper (Capsicum annuum) under greenhouse conditions.

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.

Photosynthetic Pigments and Biochemical Response of Zucchini (Cucurbita pepo L.) to Plant-Derived Extracts, Microbial, and Potassium Silicate as Biostimulants 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.