Effects of Arbuscular Mycorrhizal Fungi on Growth, Photosynthesis, and Nutrient Uptake of Zelkova serrata (Thunb.) Makino Seedlings under Salt Stress

Abstract

Salinity is the primary restriction factor for vegetation conservation and the rehabilitation of coastal areas in Eastern China. Arbuscular mycorrhizal fungi (AMF) have been proved to have the ability to alleviate salt stress in plants. However, the role of AMF in relieving salt stress among indigenous trees species is less well known, limiting the application of AMF in the afforestation of local area. In this study, a salt-stress pot experiment was conducted to evaluate the effects of AMF on Zelkova serrata (Thunb.) Makino, a tree species with significant potential for afforestation of coastal area. The Z. serrata seedlings inoculated with three AMF strains (Funneliformis mosseae 1, Funneliformis mosseae 2, and Diversispora tortuosa) were subjected to two salt treatments (0 and 100 mM NaCl) under greenhouse conditions. The results showed that the three AMF strains had positive effects, to a certain extent, on plant growth and photosynthesis under normal condition. However, only F. mosseae 1 and F. mosseae 2 alleviated the inhibition of growth, photosynthesis, and nutrient uptake of Z. serrata seedlings under salt stress. The two AMF strains mitigated salt-induced adverse effects on seedlings mainly by increasing the leaf photosynthetic ability and biomass accumulation by reducing Na+ content, increasing P, K+, and Mg2+ content, as well as by enhancing photosynthetic pigments content and the stomatal conductance of leaves. These results indicated that AMF inoculation is a promising strategy for the afforestation of coastal areas in Eastern China.

Arbuscular Mycorrhizal Fungi Effectively Enhances the Growth of Gleditsia sinensis Lam. Seedlings under Greenhouse Conditions

“…The F. mosseae 1 and F. mosseae 2 strains, isolated from different soil conditions by staff at the Beijing Academy of Agriculture and Forestry Science, showed no significantly different effects on the growth and nutrient concentrations of G. sinensis seedlings. Similar results were also found on Z. serrata seedlings [19]. The correlation analysis between mycorrhizal dependency and increased nutrient accumulation indicated that increased biomass by AMF was significantly associated with increased P and K content in all three organs, and with N content in the leaf and stem.…”

“…Photosynthetic pigments and photosynthetic parameters being enhanced by AMF has been reported by a number of researchers [12,19]. Our results showed that Chl and Chl a concentrations were increased after inoculation with each of the AMF strains.…”

“…However, the positive effects of F. mosseae on plant growth were not always the best, especially when compared to other AMF species. Zelkova serrata seedlings inoculated with D. tortuosum grew better than seedlings inoculated with F. mosseae [19], and the total dry weight of mulberry seedlings inoculated with Rhizoglomus intraradices was 17.56% higher than that of seedlings inoculated with F. mosseae [24]. These studies indicated that the efficacy of the AMF species depends on the plant species [25].…”

“…Leaf photosynthetic pigments (Chl, total chlorophyll; Chl a, chlorophyll a; Chl b, chlorophyll b) were extracted with 80% acetone as described by Zhang et al [18]. Photosynthetic parameters, including leaf net photosynthetic rate (P n , µmol CO 2 m −2 s −1 ), stomatal conductance (G s , mmol m −2 s −1 ), and transpiration rate (T r , mmol H 2 O m −2 s −1 ), were measured in the third fully expanded leaf using a portable photosynthesis system (LI-6400; LI-COR, Lincoln, NE, USA) during the day of plant harvest between 09:30 and 11:30 prior to harvest [19]. The parameters were determined under the following conditions: photosynthetically active radiation, 1000 µmol m −2 s −1 ; CO 2 concentration, 390 µmol mol −1 ; leaf temperature, 25 • C; leaf humidity, 35%-50%; and air flow rate, 0.5 dm 3 min −1 .…”

Physiological mechanism of enhancing salinity tolerance of Gleditsia sinensis Lam. by arbuscular mycorrhizal fungi

“…The leaf relative water content (RWC) was measured according to the previous method described by Wang et al (2019) using the following formula: RWC = (FW -DW) / (TW -DW) x 100%, where FW is fresh weight, DW is dry weight, and TW is turgid weight obtained after the leaf was soaked for 24 h in deionized water. The membrane stability index (MSI) was estimated according to the method described by Talaat and Shawky (2014) using the formula: MSI = (1 -C1/C2) x 100%, where C1 is the electrical conductivity bridge after the leaves were heated at 40 °C for 30 min in a water bath and C2 is the electrical conductivity bridge after the leaves were boiled at 100 °C in a boiling water bath for 10 min.…”