Aruscular mycorhizal fungi alter plant allometry and biomass - density relationships

TY - JOUR

T1 - Aruscular mycorhizal fungi alter plant allometry and biomass - density relationships

AU - Zhang, Qian

AU - Zhang, Lu

AU - Weiner, Jacob

AU - Tang, Jianjun

AU - Chen, Xin

PY - 2011/3

Y1 - 2011/3

N2 - Background and AimsPlant biomassdensity relationships during self-thinning are determined mainly by allometry. Both allometry and biomassdensity 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.MethodsTwo 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 ResultsShoot 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 radiusbiomass allometric exponents were not significantly affected by AMF level, but the rootshoot allometric exponent was higher in the low AMF treatment. With a high level of AMF, the biomassdensity 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.ConclusionsAMF 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.

AB - Background and AimsPlant biomassdensity relationships during self-thinning are determined mainly by allometry. Both allometry and biomassdensity 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.MethodsTwo 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 ResultsShoot 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 radiusbiomass allometric exponents were not significantly affected by AMF level, but the rootshoot allometric exponent was higher in the low AMF treatment. With a high level of AMF, the biomassdensity 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.ConclusionsAMF 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.

KW - Former LIFE faculty

KW - Arbuscular mycorrhizal

KW - fungi

KW - biomass-density relationship

KW - canopy-biomass allometry

KW - root-shoot biomass allomatry

KW - Medicago sativa

KW - self-thinning

KW - Arbuscular mycorrhizal fungi, biomass–density relationship, canopy radius–biomass allometry,

U2 - 10.1093/aob/mcq249

DO - 10.1093/aob/mcq249

M3 - Journal article

C2 - 21169608

SN - 0305-7364

VL - 107

SP - 407

EP - 413

JO - Annals of Botany

JF - Annals of Botany

IS - 3

ER -