Effect of Rice Cultivation Systems on Indigenous Arbuscular Mycorrhizal Fungal Community Structure

Abstract

Arbuscular mycorrhizal fungi (AMF) in an agricultural ecosystem are necessary for proper management of beneficial symbiosis. Here we explored how the patterns of the AMF community in rice roots were affected by rice cultivation systems (the system of rice intensification [SRI] and the conventional rice cultivation system [CS]), and by compost application during growth stages. Rice plants harvested from SRI-managed plots exhibited considerably higher total biomass, root dry weight, and seed fill than those obtained from conventionally managed plots. Our findings revealed that all AMF sequences observed from CS plots belonged (only) to the genus Glomus, colonizing in rice roots grown under this type of cultivation, while rice roots sown in SRI showed sequences belonging to both Glomus and Acaulospora. The AMF community was compared between the different cultivation types (CS and SRI) and compost applications by principle component analysis. In all rice growth stages, AMF assemblages of CS management were not separated from those of SRI management. The distribution of AMF community composition based on T-RFLP data showed that the AMF community structure was different among four cultivation systems, and there was a gradual increase of Shannon-Weaver indices of diversity (H′) of the AMF community under SRI during growth stages. The results of this research indicated that rice grown in SRI-managed plots had more diverse AMF communities than those grown in CS plots.

Community Dynamics of Arbuscular Mycorrhizal Fungi in High-Input and Intensively Irrigated Rice Cultivation Systems

“…In agreement with Watanarojanaporn et al (13), who reported that AMF are commonly present in rice roots from conventional paddy wetlands in Thailand, we found that AMF colonization in rice roots is commonly present at the heading and ripening stages though absent or rare at the early growth stages. This is in contrast to studies from Italy showing that AMF were absent in roots of rice grown under a conventional cultivation system (2,12).…”

“…Phylotype richness of root-colonizing AMF significantly increased with growth stage (P Ͻ 0.001), implying that the developmental stages of rice should be considered in the exploration of AMF function in paddy wetlands. This increase in AMF richness with growth stage could simply be due to the fact that the AMF have more time to colonize the rice roots, but it could also be related to the development of aerenchyma in rice in combination with a higher mineral nutrient requirement of rice plants at the heading and ripening stages (13).…”

“…The AMF communities of some wetland habitats have been investigated (7,8,9,10,11), but whether AMF occur in paddy rice fields under waterlogged conditions is still under debate (12). Some studies found that AMF are able to survive in waterlogged paddy wetlands (13), but there are also reports showing that AMF are absent or rare due to the anoxic conditions that often prevail in waterlogged systems (2,14).…”

Varietal differences in the growth responses of rice to an arbuscular mycorrhizal fungus under natural upland conditions

“…Although AM fungi are present in paddy wetlands, 3,4 their colonization rate decreases with increased development of aerenchyma in the roots 5 . Therefore, here we cultivated rice plants in an upland region to assess the effects of AM fungi on rice growth, like field experiments using other crops 6-8 …”

Short-term waterlogging increases arbuscular mycorrhizal fungal species richness and shifts community composition

“…Wang et al (2011) investigated AMF communities in three mangrove species and found that AMF diversity was similar to that in terrestrial ecosystems. (Watanarojanaporn et al 2013) reported high AMF diversity in wetland rice roots. Baar et al (2011) found considerable diversity of AMF in roots of Littorella uniflora submerged in lakes with low dissolved P concentrations.…”