Growth and Photosynthetic Responses of Litchi Seedlings to Arbuscular Mycorrhizal Fungal Inoculation: Differences between Two Genotypes

Yang Zhou,Xiaodi Liu,Honghui Zhu,Zengwei Feng,He Chang,Qing Yao

doi:10.15835/nbha46211096

Abstract

Arbuscular mycorrhizal (AM) fungi are beneficial symbiotic soil microorganisms and AM technology can find its potential application in the nursery of horticultural industry. When AM fungi have been successfully applied to many wood fruit tree species, little information is available in litchi (Litchi chinensis Sonn.). In this study, the seedlings of two litchi genotypes (‘Baila’ and ‘Heiye’) were inoculated with two AM fungal species (Rhizophagus irregularis and Gigaspora margarita) in the nursery conditions, and the growth and photosynthetic responses of seedlings to AM fungal inoculation were investigated. Results indicated that AM fungi significantly promoted the plant growth of ‘Heiye’ seedlings in terms of biomass, plant height, stem diameter and leaf number, while they slightly decreased these parameters of ‘Baila’. The inoculation effect can be explained by the changes in photosynthetic characteristics induced by AM fungi, because AM fungi increased Amax, Aqe, LSP and decreased LCP of ‘Heiye’ but did not affected those of ‘Baila’. Pn was not affected by AM fungi, however, regression analysis indicated a weaker relationship between biomass and Pn than those between biomass and Amax, LSP or LCP. Our results strongly suggest that AM fungi can differentially affect the seedling growth of litchi genotypes mainly via their effects on photosynthetic characteristics, and that precautions should be taken to select appropriate genotypes as rootstock if AM technology is applied in litchi nursery.

Highlights

Litchi (Litchi chinensis Sonn.) is subtropical fruit tree native to the area between southern China, northern Viet Nam and Myanmar (Menzel, 2002)
In an experiment using vermicompost as substrate, indigenous arbuscular mycorrhizal (AM) fungi promoted the plant height, leaf number and shoot length of air-layers by 132%, 750% and 68% (Sagar and Roy, 2013). While these results demonstrate the potential application of AM fungi in the air-layer propagation system, grafting propagation system is widely recognized in China because seedlings in this system are more tolerant to stresses with better developing roots
AM fungal colonization in the roots of rootstock seedlings Data in Table 1 showed that both R. irregularis and G. margarita colonized the roots well, with colonization rate varying between 54.4% and 74.8%

Summary

Introduction

Litchi (Litchi chinensis Sonn.) is subtropical fruit tree native to the area between southern China, northern Viet Nam and Myanmar (Menzel, 2002). China is the leading litchi-producing country in the world with 950 thousand metric tons of production in 2002 (Jiang et al, 2012), most litchi orchards in China are located in hilly and marginal soils These soils are typical of poor soil structure, low fertility and low pH (Wang et al, 2012), indicating the necessity of soil improvement and appropriate fertilization scheme in these orchards. AM fungi (phylum Glomeromycota) are a kind of soil fungi, ubiquitous in all terrestrial ecosystems (Rillig, 2004) They establish symbiotic relationship with plant roots and, increase their host resistance to diverse biotic and/or abiotic stresses (Zhu and Yao, 2004; Zhu et al, 2007; Sensoy et al, 2013; Yao et al, 2014; Zou et al, 2014). It is clearly plausible to apply AM technology to the production of litchi in southern China

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Discussion

Conclusion