Effect of Glomus intraradices on root morphology, biomass production and phosphorous use efficiency of Chinese fir seedlings under low phosphorus stress

Abstract

IntroductionAvailable phosphorus (P) scarcity in the highly weathered soils of the subtropical forests in southern China is a serious concern. To ensure whether inoculation of arbuscular mycorrhizal fungi (AMF) with Chinese fir (Cunninghamia lanceolata) under low P stress conditions could promote its growth and P utilization capacity, an indoor pot simulation experiment was carried out with the different P supply treatments and Chinese fir seedlings as the tested material.MethodsThe experiment had two P supply treatments, no P supply (P0, 0 mmol·L-1 KH2PO4) and normal P supply (P1, 1.0 mmol·L-1 KH2PO4). The seedling in each P supply treatment was inoculated with Glomus intraradices (Gi), a widespread species of AMF in the natural environment, and with no AMF inoculation as a control treatment (CK). The Gi infection rate in the root system, root cortex tissue dissolution rate, root morphological indexes and biomass, whole plant P use efficiency, and root P use efficiency of Chinese fir were determined under different treatment conditions.Results and DiscussionThe results showed that P0 treatment significantly increased the Gi infection rate (p< 0.05). After inoculating AMF with different P supply treatments, the root cortex tissue dissolution rate was considerably enhanced. In contrast, the Chinese fir’s root length and surface area were reduced; however, the root volume did not change significantly. The average root diameter in the P0 treatment and inoculated with AMF was significantly more prominent than in the uninoculated treatment (p< 0.05). The root biomass and root-to-shoot ratio at different P supply treatments were significantly higher in the Gi infection treatment than in the CK group. Under different P supply treatments, root inoculation with Gi promoted root P use efficiency and whole plant P use efficiency. In conclusion, low P stress condition promoted the colonization of AMF in the root system, increased the dissolution of root cortex tissue, root volume, and the average diameter, and promoted root biomass accumulation and P use efficiency.

Effect of arbuscular mycorrhizal symbiosis on growth and biochemical characteristics of Chinese fir (Cunninghamia lanceolata) seedlings under low phosphorus environment

“…Our previous study found that the colonization rate of R.i in the roots in P0 treatment was higher than that in P1 treatment ( p <0.05). And the colonization rate of R.i in the roots of Chinese fir seedlings was the highest at P0, up to 69.81%, which was 1.47 times that of P1 ( Tian et al, 2023 ).…”

“…1 ). The second is the inoculation of R.i strain P0 treatment; the colonization rate in seedling roots is 1.47 times that of P1 treatment ( Tian et al, 2023 ). This may be because, at normal levels of P supply, plants can take up enough P by their root extension.…”

“…The Chinese Fir Engineering Technology Research Center of the State Forestry and Grassland Administration cultivated these seedlings. The chosen seedlings exhibit high nutritional requirements, strong adaptability, and moderate growing periods to be suitable for reflecting the actual situation and drawing accurate and reliable research conclusions ( Tian et al, 2023 ). We conducted experimental research from March 2019 to June 2019, all the seedlings were planted in polyethylene pots in a glasshouse at the Forestry College, Fujian Agriculture and Forestry University.…”

“…According to the previous test methods, the experimental instruments and Chinese fir seedlings were disinfected and sterilized to reduce exogenous AMF infestation ( Tian et al, 2023 ). Two P supply level treatment groups were set up, each with three AMF inoculation treatments of F.m or R.i and no AMF, respectively.…”

“…And 200 ml of pure water was poured every 5 days in the afternoon. The detailed implementation method refers to our previous research ( Tian et al, 2023 ). The tested seedlings were harvested after 90 days.…”