Agriculture Reference
In-Depth Information
suggest that polyanines are related to growth of rice roots
cultured
in vitro
(Lee 1997).
The nature and mechanism of resistance of rice plants to
chilling stress the effects of low temperature treatment (8ºC)
on the photosynthetic rate and some important compounds
forming redox cycles were related. The varieties of rice used
are two japonica rice varieties, i.e., Taipei309 and Wuyujing,
three indica rice varieties, i.e., IR64, Pusa and CA 212 and one
intermediate type, i.e., Shanyou 63. Three types of varieties
were compared. The light intensity -photosynthesis curves,
CO
2
-photosynthesis curves, primary photochemical effi ciency
(Fv/Fm), active oxygen species (AOS) (O
2
-H
2
O
2
), glutathione
(both oxidized and reduced forms) and ascorbate contents in
their six-week old seedlings were measured before and after
chilling treatment. The results showed that relative to the rice
varieties chilling tolerance such as Taipei 309 and Wuyujing, the
sensitive ones indica IR64, Pusa and CA212 exhibited stronger
inhibition of maximum photosynthetic rate (Pmax) and a
decrease in Fv/Fm, which lead to the accumulation of AOS.
It was found that the glutathione disulphide (GSSG) content
in the glutathione pool and that of dehydoascorbate (DHA)
in ascorbate pool of the leaves of these sensitive ones under
chilling were induced to increase obviously. The correlation
coefficient between the increase in GSSG, DHA and the
decrease in chl content were 0.701 ** and -0.656 ** respectively.
This indicated that the regeneration of reduced glutathione
reduction of chl content, and the inhibition of photosynthetic
activity. The changes in japonica Taipei 309 and Wuyujing were
small. And the changes in indica hybrid were lying between
the above mentioned types. Particularly, the ratio of ASA/DHA
and GSH/GSSG showed similar changes as those in chl content.
The correlation coeffi cient among chl content and ASA/DHA,
GSH/GSS were signifi cant.
