Abstract:
Contamination of soil by heavy metals is a worldwide phenomenon, which has dire
consequences on human health, agriculture, and the environment. Among heavy metals,
Lead (Pb) is one of the most abundant environmental pollutants. Being readily absorbed
by plants, it exerts toxic effects causing altered plant morpho-physiological and
biochemical attributes. There is a dearth of research studies in Sri Lanka to elucidate the
effect of Pb on rice. Thus, the current study was conducted to assess the effect of Pb on
germination and early vegetative development of selected five traditional (Kuruluthuda,
Pachchaperumal, Godaheenati, Suwandel, and Sudurusamba) and two newly improved
(Bg 352 and Bg 360) rice varieties. The plants were exposed to 0, 10, 50, and 100 µM of
Pb concentrations in a completely randomized design, with four replicates. Germination
energy, speed of germination, and final germination percentage were taken 7 days after
sowing. The average root length and average shoot length were taken 7th day after
transplanting (14 days after sowing). The data were analysed using SAS 9.1 statistical
software and mean separation was done using Duncan’s Multiple Range Test at p <0.05.
The results revealed that the germination of each tested variety was not significantly
(p <0.05) affected even at the highest Pb concentration (100 µM). However, even at the
least Pb concentration (10 µM), variety Kuruluthuda, Pachchaperumal, Godaheenati, Bg
352 and Bg 360 showed a significant (p <0.05) reduction in shoot length (10.92±0.76,
14.77±0.43, 9.98±0.69, 8.43±0.48 and 8.95±0.63 cm respectively) and
Variety Pachchaperumal, Bg 352 and Bg 360 showed a significant (p <0.05) reduction in
root length (12.08±0.70, 14.74±0.92 and 13.3±0.70 cm respectively) compared to the
control. As per the preliminary results, Suwandel and Sudurusamba were least affected in
the parameters tested. Thus, these two varieties have the potential to tolerate Pb toxicity
in the early vegetative stages of development.
Keywords: Lead toxicity, Traditional rice, Improved rice, Germination, Early vegetative
growth
