Influence of arbuscular mycorrhizae on photosynthesis and water status of maize plants under salt stress

Abstract

The influence of arbuscular mycorrhizal (AM) fungus Glomus mosseae on characteristics of the growth, water status, chlorophyll concentration, gas exchange, and chlorophyll fluorescence of maize plants under salt stress was studied in the greenhouse. Maize plants were grown in sand and soil mixture with five NaCl levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg dry substrate) for 55 days, following 15 days of non-saline pretreatment. Under salt stress, mycorrhizal maize plants had higher dry weight of shoot and root, higher relative chlorophyll content, better water status (decreased water saturation deficit, increased water use efficiency, and relative water content), higher gas exchange capacity (increased photosynthetic rate, stomatal conductance and transpiration rate, and decreased intercellular CO(2) concentration), higher non-photochemistry efficiency [increased non-photochemical quenching values (NPQ)], and higher photochemistry efficiency [increased the maximum quantum yield in the dark-adapted state (Fv/Fm), the maximum quantum yield in the light-adapted sate (Fv'/Fm'), the actual quantum yield in the light-adapted steady state (phiPSII) and the photochemical quenching values (qP)], compared with non-mycorrhizal maize plants. In addition, AM symbiosis could trigger the regulation of the energy biturcation between photochemical and non-photochemical events reflected in the deexcitation rate constants (kN, kN', kP, and kP'). All the results show that G. mosseae alleviates the deleterious effect of salt stress on plant growth, through improving plant water status, chlorophyll concentration, and photosynthetic capacity, while the influence of AM symbiosis on photosynthetic capacity of maize plants can be indirectly affected by soil salinity and mycorrhizae-mediated enhancement of water status, but not by the mycorrhizae-mediated enhancement of chlorophyll concentration and plant biomass.

Effects of Mycorrhizal Fungi Inoculation on Green Pepper Yield and Mineral Uptake under Irrigation with Saline Water

“…These findings are in agreement with other researchers working on different vegetable crops, who reported that salinity not only affects the host plant growth but also the AM fungi colonization [2,[6][7][8]. Salinity can reduce AM colonization capacity, spore germination and inhibiting growth of hyphae of the fungus [12,22,23]. These reports have indicated that the negative effects of salinity on the AM fungus probably due to the direct effect of present salts on the fungi [22,24].…”

“…Inoculation of transplants prior to salt exposure might help bypassing the potential inhibitory effects that salt could have on AM fungal spore germination. Such inhibitory effects of salinity on rate of mycorrhizal colonization have been reported [12,22,23]. The procedure used in this study of pre-inoculating transplant seedlings with AM fungi can be of practical importance in the cultivation of many horticultural crops grown under saline conditions.…”

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“…Salinity significantly depressed G. mosseaecolonization but not P. occultum-colonization, implying that fungal species provide a different capacity to respond to salinity. This is in agreement with several studies on maize 15 and zucchini 16 . Salinity has been shown to decrease growth characteristics of citrus seedlings in saline soils ( Table 1).…”

Physiological responses of crop plants against Trichoderma harzianum in saline environment

“…From the present investigation, it was clearly observed that the dark adapted quantum yield (F v /F m ratio), performance index (PI abs ), photochemical quenching (qP) and stomatal conductance (g s ) were decreased with the increase in salinity concentration but increased by Th application. This could be due to an increase in chlorophyll concentration by the application of Trichoderma in saline environment (Sheng et al 2008).…”