TITLE:
Influence of Selenium on Growth, Antioxidants Production and Physiological Parameters of Rice (Oryza sativa L.) Seedlings and Its Possible Reversal by Coapplication of Sulphate
AUTHORS:
Debarati Das, Paulin Seal, Asok K. Biswas
KEYWORDS:
Rice, Selenate, Sulphate, Growth, Biochemical Changes
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.10 No.12,
December
25,
2019
ABSTRACT: The effect of selenate (Na2SeO4) and sulphate (Na2SO4) was
studied on growth and metabolism in two rice cultivars cv. satabdi and cv. khitish. Selenate at low
concentration (2 μM) expressed growth
promoting effect on rice seedlings as opposed to its high concentration
(≥20 μM) where the test seedlings showed stunted growth
with browning at the apices of both roots and shoots. The chlorophyll contents
showed a dose dependent effect. Both chlorophyll a and chlorophyll b contents were inhibited with increase in selenate concentrations. The effect
was more pronounced in cv. satabdi compared to cv. khitish.The level of accessory pigments was deferentially affected by selenium treatment. Simultaneously, the fluorescence intensity and Hill activity decreased with increase in selenate concentrations in the test seedlings. It is assumed that selenium plays a protective role in plants subjected
to stress and prevents the formation of reactive oxygen species (ROS) in the
cells. Higher selenate concentrations (≥20 μM)
exerted variable effect on the activities
of enzymatic antioxidants viz.; superoxide dismutase (SOD), catechol peroxidase (CPX) and catalase (CAT) in the test seedlings. The activity of
SOD increased with increase in selenate
concentrations, whereas activities of CAT and CPX decreased. Under high
selenate concentrations, the levels of oxidative stress markers, viz.; proline,
H2O2 and MDA were
also enhanced. Selenium induced accumulation of total soluble sugar and
increased the level of both reducing and non reducing sugars in both the test
cultivars. The starch contents concomitantly decreased with rise in selenate concentrations. Moreover, the nutrient contents of
test seedlings were significantly influenced by selenium. The Na and K levels gradually increased
whereas Ca, Mg and Fe levels decreased on application of
selenate. Joint application of 10 mM sulphate and selenate
showed significant alterations on all parameters tested with respect to
selenate treatment alone. Partial to complete amelioration occurred in the test
seedlings treated with high concentrations of selenate and sulphate. Our study
shows that selenium at low concentration had a stimulatory effect on growth and
metabolism as against high concentrations which proved to be toxic to the rice seedlings obtained from both the cultivars. Effects were more pronounced in cv. satabdi than
in cv. khitish which is considered to be
comparatively tolerant to selenium. The dose
dependent influence of selenium on the physiological
and biochemical responses of test seedlings
may be reversed by co-application with sulphate.