Efficiency of Salicylic Acid Application on Postharvest Perishable Crops - Salicylic Acid: Plant Growth and Development - page 342

5 Control of Post-Harvest Diseases by Salicylic Acid
Salicylic acid (SA) is an endogenous signal molecule, playing a significant role in
the control of post-harvest diseases and also an inducer of disease resistance in
plants (Joyce and Johnson 1999 ). Some of the results reported by the researchers
regarding the effect of SA on the control of post-harvest diseases in different
horticultural commodities are showed in Table 2 . Beasley et al. ( 1999 ) reported
that SA postharvest applications can reduce storage diseases caused by Alternaria
and Epicoccum sp. in Geraldton waxflower cv. CWA Pink (Chamelaucium unci-
natum). The SA application is also found to induce systemic resistance in tomato by
incompatible race of Cladosporium fulvum (Cai and Zheng 1999 ). Foliar appli-
cation of SA has led to protection of postharvest Rock melon and Hami melon
fruits from diseases (Huang et al. 2000 ). Treatment with 2.0 mg/L of SA could
suppress postharvest anthracnose disease severity caused by Collectotrichum glo-
eosporioides in mango fruit cv. Kensington Pride and also improved resistance
against in vitro antifungal activity of Cladosporium cladosporioides (Zainuri et al.
2001 ). These induced defense responses involve an increase in PAL, chitinase,
b-1,3-glucanase and POD activities (Meena et al. 2001 ). According to Qin et al.
( 2003 ), a study on sweet cherry fruit, SA treatment at the concentration of
0.5 mmol/L was effective to inhibit blue mould (Penicillum expansum) and alter-
naria (Alternaria alternate) rots without any surface injury. Yao and Tian ( 2005 )
demonstrated that SA treatment at the concentration of 2.0 mmol/L could exhibit
antifungal effects against pathogens and fungal toxicity of Monilinia fructicola in
sweet cherry fruits during stored at 25 8 C and alsosignificantly inhibited the mycelia
growth and spore germination of the pathogen in in vitro. Exogenous application of
SA also increased resistance to Botrytis rot in certain produces, such as lily leaves
(Lu and Chen 2005 ) and table grape (Asghari et al. 2009 ). Harvested cluster of vitis
vinifery L. 'Bidaneh Sefid' and 'Bidaneh Ghermez' treated with SA at the con-
centration of 1, 2 and 4 mmol/L effectively reduced water loss and fungal decay
and increased berry firmness (Sarikhani et al. 2010 ). Such an increase in resistance
was correlated with enhanced expression or/and activities of glucanase and chiti-
nase (Yao and Tian 2005 ; Derckel et al. 1998 ). Aghdam et al. ( 2011 ) reported that
the vapour treatment of SA at a nontoxic concentration (32 lL/L) was effective in
reducing fungal decay in Hayward kiwifruit by reducing CAT and ascorbate-POD
activities, which subsequently increase intra-cellular H 2 O 2 concentration. The
increase in H 2 O 2 concentration may be involved in the enhancement of disease
resistance (Zeng et al. 2006 ). Similarly, Janda et al. ( 2003 ) reported that SA
treatment resulted in temporary reduction of CAT and increased H 2 O 2 level where
H 2 O 2 acts as a second messenger in the activation and expression of defense related
genes. Additionally, postharvest applications of SA in a concentration dependent
manner from 1 to 2 mmol/L effectively reduced fungal decay in Selva strawberry
fruits (Babalar et al. 2007 ). Gholami et al. ( 2010 ) found that the immersion in
2-3 mmol/L SA for 5 min before cold storage was effective to the fungal decay
resistance of sweet cherry fruits, during storage. These findings reveal that