Aruscular mycorhizal fungi alter plant allometry and biomass - density relationships

Research output: Contribution to journalJournal articleResearchpeer-review

Qian Zhang, Lu Zhang, Jacob Weiner, Jianjun Tang, Xin Chen

Background and Aims Plant biomass–density relationships during self-thinning are determined mainly by allometry. Both allometry and biomass–density relationship have been shown to vary with abiotic conditions, but the effects of biotic interactions have not been investigated. Arbuscular mycorrhizal fungi (AMF) can promote plant growth and affect plant form. Here experiments were carried out to test whether AMF affect plant allometry and the self-thinning trajectory.
Methods Two experiments were conducted on Medicago sativa L., a leguminous species known to be highly dependent on mycorrhiza. Two mycorrhizal levels were obtained by applying benomyl (low AMF) or not (high AMF). Experiment 1 investigated the effects of AMF on plant growth in the absence of competition. Experiment 2 was a factorial design with two mycorrhizal levels and two plant densities (6000 and 17 500 seeds m-2). Shoot biomass, root biomass and canopy radius were measured 30, 60, 90 and 120 d after sowing. The allometric relationships among these aspects of size were estimated by standardized major axis regression on log-transformed data.
Key Results Shoot biomass in the absence of competition was lower under low AMF treatment. In self-thinning populations, the slope of the log (mean shoot biomass) vs. log density relationship was significantly steeper for the high AMF treatment (slope = –1·480) than for the low AMF treatment (–1·133). The canopy radius–biomass allometric exponents were not significantly affected by AMF level, but the root–shoot allometric exponent was higher in the low AMF treatment. With a high level of AMF, the biomass–density exponent can be predicted from the above-ground allometric model of self-thinning, while this was not the case when AMF were reduced by fungicide.
Conclusions AMF affected the importance of below-ground relative to above-ground interactions and changed root vs. shoot allocation. This changed allometric allocation of biomass and altered the self-thinning trajectory.
Original languageEnglish
JournalAnnals of Botany
Volume107
Issue number3
Pages (from-to)407-413
Number of pages7
ISSN0305-7364
DOIs
Publication statusPublished - 2011

    Research areas

  • LIFE - Arbuscular mycorrhizal, fungi, biomass-density relationship, canopy-biomass allometry, root-shoot biomass allomatry, Medicago sativa, self-thinning

ID: 33235018