Arbuscular mycorrhizal fungi colonization regulates root traits and soil carbon economic strategies

Abstract

Background: The symbiotic interaction between arbuscular mycorrhizal fungi (AMF) and roots can change root traits, soil carbon - nitrogen processes and crop yield. However, the precise mechanisms by which AMF affect soil carbon economic strategies and crop yield remain unclear. A two - factor pot experiment was done with cotton. Factor 1 was nitrogen application (1.5, 1.0, 0.5 g·kg−1), Factor 2 was AMF treatment (colonization and non - colonization) to study relationships between AMF and root traits, nutrient strategies, yield. Results: The analysis of the root economic spectrum reveals that after inhibiting AMF colonization in roots, root nitrogen content (RNC), root intersection count (RIC), specific root length (SRL), root branching intensity (RBI), specific root area (SRA), and root tip count (RTC) adopting an acquisitive strategy, whereas AMF colonization and root diameter (RD) showed a conservative strategy. When AMF normally colonizes roots, AMF colonization, RNC, RBI and RTC exhibit conservative strategy, whereas SRA, RD, SOC and leaf nitrogen content (LNC) display an acquisitive strategy. Additionally, there is a non - linear relationship between root traits and seed - cotton yield. Notably, AMF colonization leads to variability in the relationships between SRA and yield, and between RTC and yield. Conclusions: Under nitrogen reduction conditions, AMF colonization can enhance nitrogen acquisition by optimizing root characteristics (SRA and RBI), coordinating nitrogen metabolism between leaves and roots, and adjusting the soil carbon economic strategy. In addition, AMF hyphae will adopt a strategy of slowly acquiring nitrogen as a reward for plants, which is one of the key factors contributing to the observed differences between the trends in root morphology and seed - cotton yield.