Agriculture Reference
In-Depth Information
TABLE 14.3
(Continued)
Crop
AMF + bioagent
Beneficial effect
Reference
Tangerine
G
.
mosseae
and
G
.
geosporum
Drought and enhanced
growth
Wu et al. (2007)
Ber
Glomus
sp.
Net photosynthesis
and transpiration
Mathur and
Vyas (1995 &
1996)
14.3.3 DROUGHT AND SALINITY STRESS
Plant colonized by AM fungi can tolerate and recover more rapidly from
soil water deficits than plants without AM fungi plants colonized by AM
fungi can tolerate and recover more rapidly from soil water deficit than
plants without AM fungi (Sanchez-Diaz and Honrubia, 1994). Mycorrhi-
zal symbiosis can protect host plants against detrimental effects caused by
drought stress. Alleviation of salt stress by arbuscular mycorrhizal
Glomus
species has been shown (Ruiz-Lozano et al., 1996). Several mechanisms
have been proposed to explain the protection of AMF symbiosis, such as
changes in plant hormones, increased leaf gas exchange and photosyn-
thetic rate; direct hyphal water uptake from the soil and transfer to the
host plant, enhanced activity of enzymes involved in antioxidant defense,
nitrate assimilation, enhanced water uptake through improved hydraulic
conductivity and increasing leaf conductance and photosynthetic activity
osmotic adjustment and changes in cell-wall elasticity.
Often mycorrhizal improvement of drought tolerance occurs
via
im-
proved acquisition of phosphorus, nitrogen and other growth promoting
nutrients by AMF plants. The influence of AMF on water uptake and trans-
port may be a secondary consequence of enhanced host phosphorus nu-
trition. Mycorrhiza can also reduce the impact of environmental stresses
such as salinity. The introduction of AMF to sites with saline soils may
improve early plant tolerance and growth and increased protection from
salt stress. High level of proline is known to afford protection to various
enzyme systems against dehydration. AMF inoculation has been found
to increase the sugar levels in the plants. The higher sugar accumulation
favors the plant in maintaining the osmotic balance and preventing dehy-
