Abstract:
Iron toxicity is one of the most severe abiotic limitations for paddy
cultivation in low-country wet zone (LCWZ) of Sri Lanka, because of its
negative impact on rice yield. The present study examined root
characteristics of two rice varieties, i.e. Fe tolerant Bw 267-3 and Fe
susceptible Bw 272-6b grown in naturally iron-rich soils at Regional Rice
Research and Development Center (RRRDC), Bombuwala, in 2017/2018
‘Maha’ season. Plants were grown in field in a Complete Randomized
Block Design, with three replicates. Selected morphological characters and
physiological parameters of roots were examined at two growth stages; the
maximum tillering and flowering. The results showed that, soil Fe content
and soil pH in selected rice field at time of planting was 605.74 ± 160.51
mg/kg and 4.84 ± 0.20 respectively, which could induce toxic effects in rice
plants. The root length, root volume, number of adventitious roots and root
dry matter in Bw267-3 were significantly higher than in Bw272-6b at both
growth stages, confirming their previously demonstrated tolerant and
susceptible traits (one-way ANOVA: F=134.97, p<0.05). The total iron
content in root plaque was greater in susceptible Bw272-6b than in tolerant
Bw267-3 at both growth stages, while the iron content inside the root
showed a reverse pattern. As toxicity symptoms are linked to the ability of
iron to pass into roots and thereby to other parts of paddy plant, the
disparity in root growth and iron accumulation demonstrated between the
two varieties in the present study would most likely be linked to their
inherent traits of iron toxicity tolerance.
