Field Inoculation of Arbuscular Mycorrhizal Fungi Improves Fruit Quality and Root Physiological Activity of Citrus

Ming-Ao Cao,Elsayed Fathi Abd_Allah,Stephan Wirth,Peng Wang,Abeer Hashem,Qiang-Sheng Wu

doi:10.3390/agriculture11121297

Abstract

Soil arbuscular mycorrhizal (AM) fungi form a mutualistic symbiosis with plant roots and produce many benefits on host plants under potted conditions, while field inoculation of AM fungi on citrus (a woody plant) has been rarely reported. The present study aimed to analyze the changes in mycorrhizal growth, root vitality, and fruit quality of Citrus reticulata Blanco var. Ponkan mandarin cv. Jinshuigan grafted on Poncirus trifoliata L. after inoculation with a mix of AM fungi (Diversispora versiformis, Funneliformis mosseae, and Rhizophagus intraradices) and single F. mosseae. After the second year of AM fungal inoculations, root mycorrhizal colonization (%), root vitality, hyphal length in soil, and easily extractable glomalin-related soil protein content were significantly increased, while difficult-to-extract glomalin-related soil protein content was decreased. Two mycorrhizal fungal inoculation treatments collectively improved fruit quality parameters such as polar diameter, equatorial diameter, the weight of single fruits, fruit peel, and sarcocarp, coloration value, and soluble solids content. Our study, therefore, suggested that field inoculation with AM fungi improved root physiological activities in terms of mycorrhizal growth and root vitality and thus improved fruit quality. The effect of mixed-AM treatment was more significant than that of F. mosseae alone.

Highlights

Arbuscular mycorrhizal (AM) fungi are beneficial soil microorganisms widely existing in nature colonizing the roots of about 80% of land plants including cereals, vegetables, and fruit trees [1]
There was and no significant difference in extractable glomalin-related soil protein (EE-Glomalin-related soil proteins (GRSP)) and difficult-to-extract glomalin-related soil protein (DE-GRSP) concentrations between mixed-AMF and F. mosseae inoculation (FM) treatments
On fruit quality, rootroot mycorrhizal colonization, andand soil soil hyphal length were better than thatofofsingle singleFM

Summary

Introduction

Arbuscular mycorrhizal (AM) fungi are beneficial soil microorganisms widely existing in nature colonizing the roots of about 80% of land plants including cereals, vegetables, and fruit trees [1]. GRSP is considered to contribute to pools of soil organic carbon and providing positive impacts on plant growth [6,7]. The benefits that such AM fungi bring to host plants provide new pathways for the improvement of plant growth as well as sustainable agriculture and environmental management [8]. Paskovic et al [19] analyzed the field response of AM fungal inoculation to fruit quality of tomato. They found an increase in total nitrogen (N), magnesium (Mg), and hydrophilic phenol contents in fruit. The application of AM fungi to plants in the field and further evaluation of its benefits are limited, especially in citrus plants [20]

Results

Discussion

Conclusion