Dados do Trabalho

Título

THE INTERACTIVE EFFECT OF SILICON AND ARBUSCULAR MYCORRHIZAL FUNGI ON WHEAT PLANTS CULTIVATED UNDER WATER DEFICIT STRESS

Resumo

Although the positive impacts of Si fertilization or arbuscular mycorrhizal fungi (AMF) on plants exposed to drought have been widely documented, the mechanisms underlying the synergistic action between Si and AM symbiosis under water limitation have been scarcely addressed. Here, we investigated the combined effect of Si and AMF on physiological traits of wheat plants cultivated under water deficit stress. A pot experiment by using two irrigation regimes [85% of water holding capacity (WHC) and 40% WHC], two Si doses (0 or 1000 mg Si kg-1 soil), and two AMF levels (-AMF, +AMF; using Claroideoglomus claroideum as inoculant) was conducted. Plants were harvested at tillering stage, and mycorrhizal traits, relative water content (RWC), water potential (Ψw), CO2 assimilation (A), stomatic conductance (gs), transpiration rate (E), PSII photochemical efficiency (Fv/Fm), water use efficiency (WUE), chlorophyll a (Chla), chlorophyll b (Chlb), and carotenoids were evaluated. A decrease of AMF spore density and total extraradical AMF hyphae was found under water deficit, whereas AMF colonization increased. Despite Si did not induce any change in AMF colonization at 40% WHC, Si+AMF increased both AMF spore density and extraradical AMF hyphae under water shortage. The RWC was reduced by water limitation, but it reached a similar level of well-watered plants when Si, AMF or Si+AMF were applied. Water deficit also reduced the leaf Ψw, which was improved by Si supplied alone or in combination with AMF. Likewise, photosynthetic traits and WUE decreased in plants exposed to low water availability. However, Si and AMF decreased E, and increased A, Fv/Fm and WUE at 40% WHC. Photosynthetic pigments also decreased by water deficit, but Chla/b was not altered by the irrigation regime or Si and AMF treatments. Interestingly, Chla, Chlb, Chla+b and carotenoids increased as a consequence of Si or AMF application to low-watered plants, with a more noticeable effect in the Si+AMF treatment.

Palavras-chave

silicon; arbuscular mycorrhizal fungi; Triticum aestivum; water deficit stress.

Instituição financiadora

This work was supported by the FONDECYT Regular Projects N° 1201257 and N° 1220190, and the FONDECYT Postdoctoral Projects N°3220092 and N° 3210588.

Agradecimentos

This work was supported by the FONDECYT Regular Projects N° 1201257 and N° 1220190, and the FONDECYT Postdoctoral Projects N°3220092 and N° 3210588.