Agriculture Reference
In-Depth Information
9.2.1 Exogenous NO Donors Acting on Dormancy
and Germination of Seeds and Plant Greening
The delayed germination until optimal environmental conditions is named dor-
mancy (Bewley
1997
; Arc et al.
2013
). Positive effects of application of
NO-generating compounds such as nitrate, nitrite, sodium nitroprusside (SNP),
and acidified nitrite were reported on dormancy release and germination of
Amaranthus retroflexus
L. In this case, NO scavenger inhibited the stimulatory
effects of exogenous NO-generating compounds on germination of seeds (Liu
et al.
2011
). On the contrary, the break of deep dormancy of apple seeds upon
treatment with NO donors (SNP or acidified nitrite) or HCN was reported
(Gniazdowska et al.
2010
). An increase of germination (over 60 %) after treatment
of apple seed with NO donors and HCN was also reported. In this case, an
improvement in the plant greening by increasing chlorophyll content in seedlings
was reported (Gniazdowska et al.
2010
). Similar result with the application of SNP
in barley seedlings increased chlorophyll, and with NO scavenger decreased chloro-
phyll concentration by ca. 30 % (Zhang et al.
2006
; Gniazdowska et al.
2010
).
These effects were related to the induction of ROS formation upon NO treatment,
since ROS are important in the protection of embryo against pathogens
(Gniazdowska et al.
2010
; Seabra et al.
2013
).
It is known that imposition of salt stress significantly reduced chlorophyll
content, photosynthetic rate, transpiration rate, and altered different chlorophyll
fluorescence attributes in plants of rice cultivars. The use of sodium nitroprusside
(nitric oxide donor) on pre-sowing seed was effective in improving chlorophyll
content, gas exchange, and chlorophyll fluorescence attributes (Habib et al.
2013
).
Recently, results showed that the inhibitory effect of NO on the embryo germi-
nation was relieved by the sodium nitroprusside (SNP) pretreatment under light.
However, the SNP pretreatment did not influence the inhibitory action of
2,5-norbornadiene (NBD) to embryo germination. The SNP pretreatment increased
the chlorophyll content in leaves of seedlings and also ROS; however, this effect
was canceled by 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO)
treatment. Relationships between RNS-mediated (NO-dependent) dormancy
removal and ROS accumulation in the embryo germination are clearly discussed
(Ling et al.
2013
).
9.2.2 Exogenous NO Donors on Plant Iron Deficiency
As iron is an important element for plant nutrition, its deficiency can cause
metabolic disorders reducing chlorophyll concentration, impairing photosynthesis
and plant respiration, and reducing plant growth (Ramirez et al.
2011
). Admini-
strations of NO donors, such as SNP,
S
-nitroso-
N
-acetylpenicillamine (SNAP), or
gaseous NO on iron-deficient maize plants, prevented interveinal chlorosis
