Sabine Ravnskov

Drought is a major abiotic factor limiting agricultural crop production. One of the effective ways to increase drought resistance in plants could be to optimize the exploitation of symbiosis with arbuscular mycorrhizal fungi (AMF). Hypothesizing that alleviation of water deficits by AMF in wheat will help maintain photosynthetic carbon-use, we studied the role of AMF on gas-exchange, light-use efficiencies, carbon/nitrogen ratios and growth and yield parameters in the contrasting wheat (Triticum aestivum L.) cultivars ‘Vinjett’ and ‘1110’ grown with/without AMF symbiosis. Water deficits applied at the floret initiation stage significantly decreased rates of photosynthetic carbon gain, transpiration and stomatal conductance in the two wheat cultivars. AMF increased the rates of photosynthesis, transpiration and stomatal conductance under drought conditions. Water deficits decreased electron transport rate and increased non-photochemical quenching (NPQ) in ‘1110’ but not in ‘Vinjett’. With AMF, nitrogen concentrations increased in roots of both cultivars, but decreased in grains of ‘Vinjett’ and in side-tiller grains of ‘1110’ regardless of water status. With water deficits, AMF colonization increased plant height in both cultivars. AMF also increased biomass and grain yield in ‘1110’ but not in ‘Vinjett’. The results showed that the improvements in growth and yield were the results of AMF-mediated increases in photosynthesis during drought stress and that the alleviating effect of AMF depended on the wheat cultivar.