Biofertilizer Application Enhances Drought Stress Tolerance and Alters the Antioxidant Enzymes in Medicinal Pumpkin (Cucurbita pepo convar. pepo var. Styriaca)

Solmaz Najafi,Hossein Nazari Nasi,Reza Amirnia,Ruveyde Tuncturk,Riyaz Z Sayyed,Murat Tuncturk

doi:10.3390/horticulturae7120588

Solmaz Najafi, Hossein Nazari Nasi + Show 4 more

Open Access

https://doi.org/10.3390/horticulturae7120588

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Journal: Horticulturae	Publication Date: Dec 17, 2021
Citations: 41	License type: CC BY 4.0

Affiliation: Van Yüzüncü Yıl Üniversitesi, Urmia University

Abstract

The effects of mycorrhiza, Thiobacillus and Nitroxin (Azotobacter and Azospirillum sp.) biofertilizers under drought stress conditions with four levels of field capacity (FC) (control(100%), 85%, 70%, and 50%) on the antioxidant enzyme activities of medicinal pumpkin (Cucurbita pepo convar. pepo var. Styriaca) were evaluated during the years 2018–2019. Irrigation levels exhibited significant effects on all studied variables, except for the catalase (CAT) enzyme. A significant correlation was observed between the effects of irrigation levels and biofertilizers on antioxidant enzymes, soluble protein content, and grain yield. The highest activity of catalase and ascorbate peroxidase (APX) enzymes was achieved using mycorrhiza in 50% FC. Increasing drought intensity and mycorrhiza stimulated glutathione reductase (GR) and guaiacol peroxidase (GPX) activities by 32% and 66%, while Nitroxin increased them by 16% and 43%, respectively. Under severe drought stress conditions, only mycorrhiza exhibited a positive effect on GR and GPX enzymes. Under moderate and severe drought stress conditions, Nitroxin increased grain yield by 13% and 12.6%, respectively. The irrigation regimes and bio-fertilizers had a significant effect on β-sitosterol percentage. The highest amount was observed at the highest level of drought stress. Among the various bio-fertilizers treatments, the application of Thiobacillus yielded the highest percentage of β-sitosterol. The results of the present study demonstrate that the application of biofertilizers is beneficial in coping with drought stress.

Highlights

Introduction iationsReactive oxygen species (ROS) are very reactive and toxic
This study aimed to investigate if bio-fertilizers (Nitroxin, mycorrhiza, and Thiobacillus sp.) could protect the medicinal pumpkin against the impact of drought stress, thereby increasing its drought tolerance
Biofertilizers could stimulate the activity of guaiacol peroxidase (GPX), glutathione reductase (GR), ascorbate peroxidase (APX)

Summary

Introduction

Different biotic and abiotic stresses, e.g., drought, salinity, heavy metals, extreme temperatures, nutrient deficiency, air pollution, herbicides, and pathogen attacks, may disrupt the balance between ROS synthesis and scavenging, resulting in a sharp increase in the intracellular levels of ROS, which can be significantly harmful to cell structures [1]. O2 − -superoxide radical, H2 O2 –hydrogen peroxide, and OH-hydroxyl radical, which originates from the transfer of one, two, or three electrons to dioxygen (O2 ), is the most common ROS. Plants have very efficient enzymatic superoxide dismutase (SOD); catalase (CAT); ascorbate peroxidase (APX); glutathione reductase (GR); monodehydroascorbate reductase (MDHAR); dehydroascorbate reductase (DHAR); glutathione

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