Abstract
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 (K
2
SiO
3
) on productivity and biochemical composition of zucchini fruits, were assessed as biostimulants. The results showed that
E. camaldulensis
LE (4,000 mg/L) + K
2
SiO
3
(500 mg/L) and
T. viride
(10
6
spore/ml) + K
2
SiO
3
(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 K
2
SiO
3
with
E. camaldulensis
LE increased the DPPH scavenging activity and the total phenolic content of zucchini fruits, in both experiments. However, the spraying with K
2
SiO
3
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.