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

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.