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University of Tennessee (2004)

Mycorrhizal symbiosis and the response of sorghum plants to combined drought and saline stresses

Cho, Keun Ho

Titre : Mycorrhizal symbiosis and the response of sorghum plants to combined drought and saline stresses

Auteur : Cho, Keun Ho

Université de soutenance : University of Tennessee

Grade : Master of Science 2004

Résumé partiel
Arbuscular mycorrhizal (AM) symbiosis has been reported often to improve the abilities of host plants to tolerate drought stress. The physiological mechanism is uncertain, but one idea is that the effect might be linked to resistance to salt stress. Several studies have shown more growth in crop plants colonized with AM fungi than nonAM control plants under salt stress. Drought and salt stresses frequently occur together in nature and their initial symptoms in plants are similar. It may be interesting to scrutinize their physiological interaction in host plant as a function of AM fungi. Therefore, the objectives of my studies were to investigate if AM influence on plant response to drought is more evident in saline soils. I hypothesized that 1) AM and nonAM plants would have different values of water relation parameters with exposure to drought and 2) AM-induced drought tolerance would be greater when plants are subjected to salt stress during drought. In two separate greenhouse experiments, sorghum was colonized with Glomus intraradices, Gigaspora margarita, or a mixture of AM species isolated from semiarid grasslands in Arizona (AZ). To induce drought stress to the host plants, watering was held after applications of soil solution. NaCl (40 mM and 80 mM) was applied to pot soil to initiate salt stress and macronutrient solution (-0.4 MPa and –0.8 MPa) was used for exposure of osmotic stress to host plants in experiment 2. To eliminate remaining salt ion in soil, a group of pots were leached heavily with distilled water in experiment 2. The pots receiving same amount of water as salt solution served as control plants. Several parameters in relation to leaf and soil water status were monitored to determine the effect of AM symbiosis under drought and salt stress.

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