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DIFFERENTIAL RESPONSES OF ONION AND GARLIC AGAINST PLANT
GROWTH REGULATORS
G.
OUZOUNIDOU1, A. GIANNAKOULA2, M. ASFI1AND
I. ILIAS2
Abstract: The effects of Gibberellic acid-GA3,
Prohexadione-Calcium, and Ethephon pre-harvest application on yield,
biomass production, photosynthetic function, lipid peroxidation and
quality characteristics of onion (Allium
cepa
L.)
and garlic (Allium
sativum
L.)
plants were investigated. Shoot length and biomass of onion and garlic,
expressed either in fresh or dry weight, increased significantly under
GA3,
while a progressive decrease under Prohex-Ca and Ethephon occurred.
Higher MDA (lipid peroxidation) values were recorded after Prohex-Ca and
Ethephon supply on onion and garlic plants; it seems that GA3
treatment prevents lipid peroxidation as measured with the help of the
TBARS method. Plants treated with Prohex-Ca and Ethephon revealed higher
peroxidase activity compared to control and GA3 treated
plants. Considering the results of MDA content and peroxidase activities
it can be assumed that GA3 treated plants are slightly
protected from the natural course of oxidative stress, which occurs
during ageing as observed for control samples. The fluctuations of
chlorophyll fluorescence parameters represent a general decline in
chloroplasts function after plant growth regulators exposure, whereas in
combination to the suppressed chlorophyll content, structural
malformations of photosystems may also occur. The production of ascorbic
acid, glucose and fructose content seems to be enhanced under GA3
in both species, while their values were depressed under Prohex-Ca
and Ethephon. Overall, only GA3
supply leads to a vigorous onion and garlic growth and yield.
1Institute
of Food Technology, National Agricultural Research Foundation, 141 23
Lycovrissi, Greece
2Department
of Crop Production, Technological Educational Institute of
Thessaloniki,Sindos 54700, Greece
*Corresponding author
geouz@nagref.gr,
geouz@yahoo.gr;
phone: (+30) 210 2845940; fax: (+30)
210 2840740
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